Fabrication design rules

Precise machining of the surfaces in contact is necessary to make pole faces accurately parallel. The required machine tolerance is about 1/50,000 of the pole diameter.

Livingston & Blewett, Particle Accelerators (1962) — p. 193

Tabletop: For 8-in poles that is ~0.00016 in (~4 um) parallelism - a surface-grinder job; non-parallel poles show up as the sinusoidal azimuthal error in field maps.

obtained by the use of such stacks in the two shimming gaps, each consisting of four disks of 0.020-in. soft iron sheet of 6, 14, 18, and 22 in. diam.

Livingston & Blewett, Particle Accelerators (1962) — p. 195

Tabletop: Scaled to 8-in poles: a stack of 0.020-in disks of roughly 1.2, 2.8, 3.6, 4.4 in diameter is a proven starting recipe for the 2-4% droop.

The magnet has tapered poles, the poles being tapered from 12-inch pole stems to 10-inch pole faces. There is a 0.7 inch thick shoulder at the pole face ... peripherally placed steel shims contribute to the uniformity of the field.

McGuire, The Iowa State University 1.5 MeV Undergraduate Cyclotron (1961) — p. 6-7

Tabletop: A concrete, machinable geometry for concentrating flux into an 8-10 inch pole face at ~1.7 T; the shoulder plus edge shims are what flatten B(r) near the outer orbit.

The pole gap is twenty-two inches, and, for any given radius, the gap variation is less than 0.005 inch.

Ramler & Parker, The Argonne 60-Inch Cyclotron — ANL-5907 (1959) — p. 10

Tabletop: Scaled to the reference machine's 8 in poles and ~2 in gap, a few-thousandths flatness/parallelism spec is achievable on a decent mill and is the tolerance to ask a machinist for.

the edges of the pole have a 45 degree taper. This is to prevent magnetic saturation at the edges of the pole. The field due to the taper also fringes less sharply.

Heuer & Baumgartner, Design of a 2 MeV Cyclotron (2009) — p. 31

Tabletop: Trivial machining step for a next machine's pole tips that buys margin against edge saturation at higher fields.

disagreement with calculation was found as the calculation average field value is 5 % higher than measured one ... the valley gap height was reduced from 100 mm to 70 mm

Antokhin et al., Magnet System for PET Cyclotron Based on Permanent Magnets (2006) — p. 2

Tabletop: Design in adjustability (a gap or shim you can still reduce after measuring), because your FEMM answer will be a few percent optimistic too.

Both cutting pole and shimming was applied to reach isochronous field. The resulting magnetic field strength is close to designed value and its shape is nearly isochronous

Antokhin et al., Magnet System for PET Cyclotron Based on Permanent Magnets (2006) — p. 2

Tabletop: Budget several map-machine-remap cycles for a next machine's pole profile; it is normal, not a sign of a bad design.

The reason for increased radial oscillations is big first harmonic of magnetic field, which caused by non-symmetric structure of central part of cyclotron magnet ... to make symmetric central magnet part by setup second hole on opposite side with respect to ion source hole.

Antokhin et al., Magnet System for PET Cyclotron Based on Permanent Magnets (2006) — p. 2-3

Tabletop: A ten-fold reduction in orbit wander for the cost of drilling a second, unused hole - directly applicable to any asymmetric feature in the reference machine's pole or chamber center.

pressure @ 0.5T 99,472 Newton/m2... ~ 1 atmosphere

Tanabe, Iron Dominated Electromagnets, Lecture 10: Forces, Stored Energy, Fringe Fields, End Chamfering (2005) — p. 10-11

Tabletop: At the reference machine's 0.59 T the poles attract with ~1.4 atm over the 8-inch pole face — about 4,500 N (~1,000 lbf); clamps and any pole-retraction scheme must carry that load (chamber lids carry the separate atmospheric load — see the lid-deflection calculator). [Corrected 2026-08-20: previously printed as "~4500 lbf", the newton value mislabeled.]

the meshing package for POISSON is rather weak and often does not have the flexibility nor is robust enough to generate difficult detailed meshes easily.

Tanabe, Iron Dominated Electromagnets, Lecture 4: POISSON — A Two-Dimensional Magnetostatic Solver (2005) — p. 10, 19

Tabletop: Saves hours on shim-profile studies where dozens of geometry variants are compared; also justifies using FEMM instead for fiddly shim shapes.

It is a public access code (it's free), maintained under contract with DOE by Los Alamos National Accelerator Laboratory (LANL) personnel.

Tanabe, Iron Dominated Electromagnets, Lecture 4: POISSON — A Two-Dimensional Magnetostatic Solver (2005) — p. 2-4

Tabletop: Free tool that runs on a PC and is the same code the Houghton thesis used - the standard amateur path to pole-profile design.

It is necessary to add a small weld bead, electrically connecting all the laminations. The core can then be grounded to a single ground point.

Tanabe, Iron Dominated Electromagnets, Lecture 8: Core Fabrication, Assembly, Installation and Alignment (2005) — p. 23

Tabletop: Single-point grounding of the yoke also matters on a solid-core machine carrying RF and HV nearby - one deliberate ground, no accidental loops.

Magnet alignment specifications... typically call for < +250 um precision transversely and vertically and < +500 um longitudinally... The cost of retrofit is high.

Tanabe, Iron Dominated Electromagnets, Lecture 8: Core Fabrication, Assembly, Installation and Alignment (2005) — p. 3, 27

Tabletop: For a single-magnet cyclotron the numbers relax, but the lesson holds: machine reference flats and leveling features into the next machine's yoke before assembly.

A true kinematic support system must have at least and at most six linearly independent supports.

Tanabe, Iron Dominated Electromagnets, Lecture 8: Core Fabrication, Assembly, Installation and Alignment (2005) — p. 38-41

Tabletop: A next machine's stand with three adjustable feet plus lateral stops gives repeatable leveling of the median plane without fighting a warped frame.

Solid iron yokes are often used in simple, flat pole contour magnets.

Tanabe, Iron Dominated Electromagnets, Lecture 8: Core Fabrication, Assembly, Installation and Alignment (2005) — p. 4-5

Tabletop: Settles the question for a next machine: a one-off DC cyclotron magnet should be solid steel; laminations buy nothing at quantity one.

At high fields, the top of the pole can saturate. The right hand figure illustrates a tapered pole which is wider at the top... a radius at the pole corner, reducing this magnetic flux stress concentration.

Tanabe, Iron Dominated Electromagnets: Design, Fabrication, Assembly and Measurements — SLAC-R-754 (2005) — p. 251-252

Tabletop: Cheap insurance for the next machine's pole design: a root taper and corner radius cost one lathe operation and keep the field map valid from low current to full excitation.

The angle of the cut is unimportant. However, a 45 degree angle cut is convenient and distributes the same angle at two points and minimizes saturation effects due to the sharp corners.

Tanabe, Iron Dominated Electromagnets: Design, Fabrication, Assembly and Measurements — SLAC-R-754 (2005) — p. 253-254

Tabletop: If the next machine's pole edge is chamfered or radiused to soften the field falloff for extraction, use ~45 degrees and bolt-on machinable end pieces so the shape can be iterated (Tanabe converged in two iterations on SPEAR3).

The aggregate of lead screw pitch and motor resolution correlates to 800 steps per inch. To further minimize the potential for backlash, field measurements are only made while stages are moving in the 'forward' direction.

Koeth & Krutzler, Field Mapping in Cyclotron Magnets (2015) — p. 2

Tabletop: A 1/800 inch (0.03 mm) grid is more than enough for an 8-12 inch pole and is buildable from surplus stepper/leadscrew parts.

After 1600 travel manipulations were executed by 2.4 million motor steps, the probe carriage reproducibly returned back to the distal point within the digital dial indicator's resolution of 0.0000 inches

Koeth & Krutzler, Field Mapping in Cyclotron Magnets (2015) — p. 4

Tabletop: Cheap insurance: an afternoon of cycling the homemade stage validates every field map you take afterwards.

a pole piece with a flat surface at the edge with a thickness sufficient for the screws and a kind of lump in the middle with a flat top

Chun, The Cyclotron Magnet and RF Oscillator (2003) — p. 8

Tabletop: Directly applicable fabrication pattern for a next machine's contoured pole caps that still bolt on.

Lbs. force on conductor = 1/1750 x kilogauss x amperes x inches length; Lbs. force between pole faces = 1/1.735 (kilogauss)^2 x (inches^2 area)

Wouters, General Recommendations for Design of Small Cyclotrons — UCRL-476 (1949) — p. 13

Tabletop: Directly applicable: at 5.9 kG on 50 in^2 poles that is ~1000 lb of attraction a next machine's bolts and spacers must carry.

It is important that the contact surfaces between yoke pieces and between yoke and pole cores be flush to eliminate additional air gaps

Wouters, General Recommendations for Design of Small Cyclotrons — UCRL-476 (1949) — p. 3

Tabletop: Directly applicable; a few thousandths of an inch of unintended air gap is a noticeable fraction of a small machine's ampere-turn budget.

the magnetic field changes too quickly near the edge of the shim. This is a result of making the shim too thick.

Morrow, Focusing in the Houghton College Cyclotron — Houghton College thesis (2015) — p. 25, 44, 46

Tabletop: Warns the builder off the obvious first shimming attempt; the useful shims are thinner than are convenient to fabricate and hold in place.

As the vacuum chamber radius is 2.2 cm larger than the radius of the magnet poles, these lids act as wide pole faces that draw the magnetic field lines out to larger radii.

Morrow, Focusing in the Houghton College Cyclotron — Houghton College thesis (2015) — p. 54-55

Tabletop: The highest-leverage cheap upgrade in this batch: swapping aluminium chamber lids for steel roughly doubles theoretical proton energy on a machine essentially identical to the reference machine's.

Pole face: 150mm, Pole gap: 39mm, Current: 70A ;NOTE: this is a slice down the middle of the magnet

Morrow, Focusing in the Houghton College Cyclotron — Houghton College thesis (2015) — p. 60-68

Tabletop: Zero-cost simulation path for a hobbyist; the appendix geometry file is a working starting template for an 8-15 cm pole magnet.

upper and lower pole tips up to 1-inch thick can be easily attached and removed - we currently have four sets of pole tips.

Koeth, Undergraduate Education with the Rutgers 12-Inch Cyclotron (2015) — p. 2

Tabletop: Probably the single best architecture decision the builder can copy: a next machine with bolt-on tips can iterate field profiles cheaply.

Trim coils increase the gap ... Very weak except in superconducting machines ... Model it before implementing it to avoid unexpected effects

Beeckman, Cyclotron Magnets — ECPM37 lecture, Groningen (2009) — p. 33, 47

Tabletop: Settles the shim-vs-trim-coil question for a small warm magnet the same way the Houghton thesis did empirically: iron wins.

The iron shaping methods zoo: Change the ratio of hill/valley spanned angle with radius ... Prevent field decrease at large radii ... Decrease the gap along radius ... Lateral edges milling ... Iron inserts ... Change local saturation

Beeckman, Cyclotron Magnets — ECPM37 lecture, Groningen (2009) — p. 34-46

Tabletop: A ranked menu of things the builder can machine on 8-inch pole tips, each demonstrated on a real cyclotron; movable flaps in particular give post-build adjustability.

Laminated: Limited thickness : 300 mm max, usual 200 mm. Good magnetic and mechanical properties. Slight anisotropy.

Beeckman, Cyclotron Magnets — ECPM37 lecture, Groningen (2009) — p. 57

Tabletop: For an amateur the practical read is: mild-steel plate stock is fine for a DC magnet; note the anisotropy if you stack plate for pole tips.

step0: Squeeze requirements and extract juice; step1: Get starting numbers from hand calculation; step2: 2d global model; step3: 3d global model; step4: 2d cuts for detailed local objects ... 2d calculations must be preferred.

Beeckman, Cyclotron Magnets — ECPM37 lecture, Groningen (2009) — p. 68

Tabletop: A workflow a solo builder can actually execute, and it puts pencil-and-paper (Zickler-style) sizing ahead of any software.

The shims were machined from 2 1/4 in. steel plate on a vertical boring mill ... The magnetization curve taken at the center of the tank with the contour shims in place is also shown.

Livingston & Boch, The Oak Ridge 86-Inch Cyclotron — ORNL-1196, OSTI 4357145 (1952) — p. 35

Tabletop: Directly applicable method: leave gap allowance for removable machined shim rings/plates so a next machine's field shaping is a measurement-and-remachining loop, not a magnet rebuild.

The U-shape of the magnet gives direct access to the top of the vacuum chamber and permits the use of an overhead crane for transferring the assembled dee system.

Livingston & Boch, The Oak Ridge 86-Inch Cyclotron — ORNL-1196, OSTI 4357145 (1952) — p. 7, 9

Tabletop: The principle (design the yoke around how you will service the chamber, not vice versa) is directly applicable to a next machine's H-frame layout.

a magnetic load of 1,055,000 lb and a vacuum load of 60,000 lb could be expected ... mating surfaces of pole bases and yoke pieces to be planes within 0.005 in. T.I.R.

Livingston & Howard (eds.), The Oak Ridge Relativistic Isochronous Cyclotron — ORNL-2648, OSTI 4275955 (1958) — p. 118

Tabletop: Direct transfer of tolerancing practice: face-grind a next machine's pole and yoke mating surfaces and check with a dial indicator; magnetic attraction, not atmosphere, is the structural design load.

The voltage breakdown strength of a resin-impregnated layer of glass cloth or cotton mesh is usually over 100 volts/mil ... necessary to utilize mica-sheet or mica-flake insulation to obtain the higher voltage-to-ground insulation.

Livingston & Blewett, Particle Accelerators (1962) — p. 278

Tabletop: Potting the reference machine's coils stops the slow insulation abrasion that coil hum causes; their low coil voltage means the resin-glass numbers alone give ample margin.

Using this type of winding allows for a more uniform field than a simple spiral winding.

Heuer & Baumgartner, Design of a 2 MeV Cyclotron (2009) — p. 32-33

Tabletop: The reference machine's 538 turns of copper tubing could be rebuilt as ~10 potted double-pancakes per pole with a cooling manifold, easing fabrication and repair.

If the design hole diameter is increased, the required pressure drop is decreased dramatically. If the fabricated hole diameter is too small... pressure drop can increase substantially.

Tanabe, Iron Dominated Electromagnets, Lecture 6: Excitation, Coil Design, System Design and Water Flow (2005) — p. 48

Tabletop: When choosing hollow conductor for a next machine, err to the larger bore; also a reason to flow-test each pancake before potting.

A single water circuit in a coil assembly should be wound from a single continuous length of conductor. Splices 'buried' within the potted insulation should not be allowed.

Tanabe, Iron Dominated Electromagnets, Lecture 9: Coil Fabrication, Testing and Electrical Safety (2005) — p. 14-16

Tabletop: For a next machine wound from copper refrigeration tubing: buy one continuous coil per water circuit, keep the shop swarf away from the winding, and verify the bore is clear before the tubing is buried in the stack.

A sick coil will exhibit waveforms whose frequency and/or damping rate changes as the voltage increases or will exhibit hash at the peak of the damped sinusoid.

Tanabe, Iron Dominated Electromagnets, Lecture 9: Coil Fabrication, Testing and Electrical Safety (2005) — p. 17-24

Tabletop: A signal generator, capacitor and scope let the builder certify the next machine's coils before they are trapped under the yoke; also hipot potted coils at 2x operating voltage + 1 kV with < 2 mA/kV leakage.

Water flow calculations made for the preliminary design may be unreliable for a coil designed with many tight turns... due to the added flow impedance of tight radius turns.

Tanabe, Iron Dominated Electromagnets, Lecture 9: Coil Fabrication, Testing and Electrical Safety (2005) — p. 25

Tabletop: The reference machine's 538-turn tubing coil is exactly the many-tight-turns case; a bucket-and-stopwatch flow test at operating pressure is the real spec, not the straight-pipe pressure-drop formula.

For a bending radius of three times the conductor width we can expect a keystoning of 3.6% ... we can ignore the effect of keystoning by systematically choosing a bending radius four times larger than the conductor width.

Zickler, Basic Design and Engineering of Normal-Conducting, Iron-Dominated Electromagnets — arXiv:1103.1119 (2010) — p. 30

Tabletop: Directly applicable to bending copper tubing for a 538-turn homemade coil: tight bends also pinch the cooling bore and risk insulation damage.

It is important for the coils should be in the air stream of one of the cooling fans (they will run hot if not).

Buckler, Solid-State, 2-Decade, 1.25 kW Linear Amplifier — Development Notebook (2015) — p. 28

Tabletop: Directly applicable to the homemade dee-tank coil, which sees circulating RF current far above the dee's DC feed current.

it has been found necessary to have these tubes spaced as closely as 2 to 3 in. to prevent local heating and warping of the D's under power.

Livingston & Blewett, Particle Accelerators (1962) — p. 175

Tabletop: At tens of watts the builder needs no water, but the warping lesson stands: dee thermal drift detunes the resonator, so keep dee structures stiff and thermally anchored.

dust should be controlled and all grease removed (even fingerprints), and under no circumstances should steel wool or coarse abrasives be used in cleaning.

Livingston & Blewett, Particle Accelerators (1962) — p. 189

Tabletop: After every chamber opening, budget an hour of gradually raised dee voltage for conditioning before expecting stable beam.

The voltage breakdown limit determines the necessary gap width. The empirically determined limit (valid for clean, flat surfaces) is d[mm] >= 1.41 x 10^-2 * phi[kV]^(3/2).

Wolf (ed.), Handbook of Ion Sources (1995) — p. 379

Tabletop: Direct rule for the reference machine's source-to-puller spacing and any dee-to-ground clearance: a few-kV dee needs sub-mm minimum, but leave margin because sputtered metal films spoil the 'clean surface' assumption fast.

Ferrite toroids wound with AWG 26 wire and surrounding two 2 inch sections of RG-8 50 Ohm coaxial cable form the coupling transformers.

Blodgett, 3.5 to 30 MHz Automatic Antenna Impedance Matching System (2012) — p. 18-19

Tabletop: A ~$5 coupler build that brackets the reference machine's 9 MHz band; the shield-through-toroid trick is the detail that makes homebrew directivity respectable.

the top and bottom of the chamber to bow in, which affected the capacitance of the dee and reduced the maximum voltage that the dee could withstand before flashing over.

Baumgartner, The Cyclotron Kids' 2 MeV Proton Cyclotron — Cyclotrons 2013, WE1PB05 (2013) — p. 2

Tabletop: Directly relevant to any thin-lid chamber on a next machine squeezed into a small magnet gap: plan support posts (clear of the beam spiral) from the start.

They found that at a critical angle of 31.5 deg, the surface charge was zero... by screening the section of the insulation surface near the cathode... the breakdown voltage was raised by a factor of approximately 2.5.

Miley & Murali, Inertial Electrostatic Confinement (IEC) Fusion: Fundamentals and Applications (2014) — p. 113-114

Tabletop: Free flashover margin for the next machine's source stalk and dee-stem insulators: cone the insulator ends at ~30 degrees toward the negative electrode and recess the triple junction behind a metal skirt.

Air spaces exist in solid and liquid dielectrics... the air will have the higher stress, possibly causing sparkover through the air space... The stress in the air gap can thus be k times that in the solid.

Miley & Murali, Inertial Electrostatic Confinement (IEC) Fusion: Fundamentals and Applications (2014) — p. 116, 119

Tabletop: The classic failure of home-built HV feedthroughs: a loose PTFE sleeve over a rod arcs in the annular air film; pot it, oil-fill it, or evacuate the annulus so Paschen cannot be satisfied.

The optimum ratio as r_i/r_o = 1/e. This optimum ratio minimizes the stresses within the coaxial electrode arrangement, independent of the material of the dielectric used.

Miley & Murali, Inertial Electrostatic Confinement (IEC) Fusion: Fundamentals and Applications (2014) — p. 117, 122-124

Tabletop: Sizes the reference machine's HV stalk directly: for a grounded 25-mm-bore chamber port, a ~9-mm center conductor minimizes field stress; and never leave a sharp-edged washer or nut on the HV end.

This phenomenon causes the cathode grid material from the IEC device to be deposited on the high-voltage (HV) stalk. That can in time cause premature breakdown at the stalk.

Miley & Murali, Inertial Electrostatic Confinement (IEC) Fusion: Fundamentals and Applications (2014) — p. 87, 105, 109

Tabletop: In the reference machine's small chamber everything sees the source; a simple washer-stack or skirt shielding the feedthrough ceramic from the chimney slit will multiply time-between-cleanings.

A standard AEI hairpin electron microscope filament floating at approximately -90 V is heated by 2 A of current ... RF pickup on each filament lead is shorted through a 0.001 uF capacitor to ground.

Yuly, The Houghton College Cyclotron: a Tool for Educating Undergraduates — Cyclotrons 2013, WE1PB01 (2013) — p. 3

Tabletop: An off-the-shelf, cheap, replaceable filament choice plus the RF-bypass detail that keeps the filament supply alive next to a live Dee.

two 12 in. split silver-plated, water-cooled copper rings which can be clamped securely around the stems; the dee stems are also silver plated over the adjustment range

Livingston & Boch, The Oak Ridge 86-Inch Cyclotron — ORNL-1196, OSTI 4357145 (1952) — p. 53

Tabletop: Scaled down: any sliding or bolted joint in the reference machine's dee-stem/coil path should be a broad, clean, plated, firmly clamped contact - RF joints, not wires, set small-resonator Q.

No solder to hold the board to the spreader, the screws are enough. Heat sink compound between copper spreader and aluminum heat sink.

Buckler, Solid-State, 2-Decade, 1.25 kW Linear Amplifier — Development Notebook (2015) — p. 10

Tabletop: Standard practice for any kW-class dee driver a home builder assembles from LDMOS boards.

a fundamental flaw in my design settings had been that all the crossover and cutoff frequencies were too low, causing too much insertion loss and high VSWR in the passband.

Buckler, Solid-State, 2-Decade, 1.25 kW Linear Amplifier — Development Notebook (2015) — p. 20

Tabletop: Schedule tuning time (this cost the author three months); the same applies to a homemade dee tank and matching network.

I also added a limiting power resistor (20 ohms at 50w) in series with 50v to the TIP102 as a precaution...with this resistor in place, a short on the 12v line will limit the current and prevent a catastrophic failure.

Buckler, Solid-State, 2-Decade, 1.25 kW Linear Amplifier — Development Notebook (2015) — p. 31-32

Tabletop: Cheap fault-tolerance rules for any homebuilt high-voltage/high-current RF deck; voltage-derating the caps matters more with the reactive load a dee presents.

This last problem has been investigated fully by Benson who recommends chemical or electrolytic polishing to produce a smooth surface and lower losses.

Fowler, Radio Frequency Performance of Electroplated Finishes — Proc. IREE Australia (1970) — p. 8

Tabletop: Polishing dee edges and stems serves double duty at 5-13 kV: lower RF resistance and higher voltage-breakdown threshold.

Rather than mounting the output transistors directly to a heat sink, they are first flow soldered to a thick copper heat spreader, which is then mounted to the heat sink.

Buckler, A Solid State 1.25 kW Linear Amplifier — QST, January 2015 (2015) — p. 3

Tabletop: At 100-500 W a copper spreader under the LDMOS pallet is cheap insurance against the die-temperature excursions that killed the reference machine's earlier MOSFET amps.

The position of the connection point at the drain trace is critical as it affects the match.

Buckler, A Solid State 1.25 kW Linear Amplifier — QST, January 2015 (2015) — p. 4

Tabletop: When copying an LDMOS pallet layout, reproduce the output-transformer connection geometry exactly; millimeter changes shift the match at hundreds of watts.

This design strategy made it impossible to fix a single component of the apparatus, such as the insulation, without replacing the entire piece.

Haas, Characterizing the Performance of the Houghton College Cyclotron — Houghton College thesis (2009) — p. 47

Tabletop: A next machine should assume sparks WILL damage insulators eventually; screw-together modularity turns a total rebuild into a one-part swap.

The screw holes need to be vented so that they do not trap air or water and slowly outgas when the dee is placed in the vacuum chamber.

Haas, Characterizing the Performance of the Houghton College Cyclotron — Houghton College thesis (2009) — p. 52

Tabletop: Directly applicable to any screwed-together dee on a next machine: unvented blind holes are virtual leaks that cap the achievable base pressure.

Ceramic spacers hold the Dee and Dummy Dee apart with a gap of 0.635 cm. The entire Dee electrode assembly is supported by three KF-16 electrical feedthroughs through ports at 120 degrees from each other.

Yuly, The Houghton College Cyclotron: a Tool for Educating Undergraduates — Cyclotrons 2013, WE1PB01 (2013) — p. 2

Tabletop: Direct fabrication template; the single-Dee-plus-dummy topology halves the RF feedthrough problem versus two live Dees.

The sides of the second set of dees are 1/8 in. copper with five loops of 7/8 in. copper tubing flattened and furnace brazed ... Both designs have proved satisfactory but the latter is much easier and less expensive.

Livingston & Boch, The Oak Ridge 86-Inch Cyclotron — ORNL-1196, OSTI 4357145 (1952) — p. 50

Tabletop: At 1.3 kV the builder needs no water; if a next machine's dee runs kilowatt-class RF, soldered-on flattened tubing along the dee lip is the proven cheap construction.

The filament is heated to incandescence by a high-frequency a-c power supply. The high-frequency is used to minimize self-destructive magnetic effects in the spiral filament.

McGuire, The Iowa State University 1.5 MeV Undergraduate Cyclotron (1961) — p. 7

Tabletop: Concrete fix for a failure mode the builder will hit at 0.6-1.7 T with a hairpin/spiral filament: filament life is a chronic tabletop problem.

Stainless steel is an excellent material up to about 1000 C... It forms low-melting alloys with tantalum and molybdenum above 900 C... Tungsten... has the highest melting point of about 3400 C and is best suited for filaments.

Wolf (ed.), Handbook of Ion Sources (1995) — p. 355

Tabletop: Do not clamp Ta filament legs directly in stainless fixtures near the hot zone; use Mo or graphite intermediate parts in the next machine's chimney.

fusion efficiency is enhanced by transparency of at least 92 percent (Donovan). The inner grid is 99.18 percent transparent with three loops

Kovalchick, Deuterium Fusion Using Inertial Electrostatic Confinement (2012) — p. 19-20

Tabletop: The transparency bookkeeping (wire cross-section vs aperture area) is the same calculation the builder needs for any grid, mesh, or slit that their beam must pass repeatedly.

The stainless steel wires previously used by Murali lasted for under a week depending on the power load. In contrast, with the W-25%Re alloy, the grid lasted for over 2 years.

Miley & Murali, Inertial Electrostatic Confinement (IEC) Fusion: Fundamentals and Applications (2014) — p. 145-146

Tabletop: W-Re thermocouple wire is commercially available in small quantities and is the best upgrade for any sputtered electrode in the reference machine's source: W durability with Ta-like workability.

Care must be exercised to electrically shield (insulate) the inner grid metallic support structure so that ions will not bombard that portion of the apparatus.

Hull, The Farnsworth/Hirsch Fusor — The Bell Jar, Vol. 6 No. 3/4 (1997) — p. 7

Tabletop: Same rule protects the reference machine's Faraday cup stalk and source supports: unshielded biased metal collects spurious current and sputters.

the anode floats inside the cathode body, being supported only by the two stainless steel wires that protrude through the alumina tubes and out the back of the cathode body.

Rovey, Ruzic & Houlahan, Simple Penning Ion Source for Laboratory Research and Development Applications (2007) — p. 1-2

Tabletop: An amateur-grade insulated feedthrough scheme (alumina tube + Ceramabond) the builder can reuse for chimney anodes or filament leads inside the next machine.

Water cooling for the cathode rod and the anode base are essential (some copper parts were melted when the ion source was run without proper cooling).

Forringer, Phase Space Characterization of an Internal Ion Source for Cyclotrons — MSU dissertation (2004) — p. 19-20

Tabletop: At the reference machine's much lower arc powers passive/conductive cooling may suffice, but the sanded-cathode arc-striking trick transfers directly.

This puller was designed for the ion source test stand to hold 50 kV... The minimum source to puller gap is 0.196 (5.0 mm).

Forringer, Phase Space Characterization of an Internal Ion Source for Cyclotrons — MSU dissertation (2004) — p. 68, 75

Tabletop: Sets the reference machine's dee-tip/puller gap voltage budget: with clean electrodes, plan on order 10 kV per mm of gap and generous edge radii.

201 through 284 / 1/8 / .139 +/-.004 / .101 to .107 / .028 to .042 / 20 to 30 / .177 to .187 / .158 to .164 / .010 to .025

Parker Hannifin, O-Ring Handbook — Design Chart 4-3: O-Ring Face Seal Glands — p. 1

Tabletop: Directly hands the mill the numbers for every lid and port groove on the next machine's chamber; note the vacuum groove width is narrower than the liquid-service column.

Surface finish X: 32 for liquids, 16 for vacuum and gases. Finishes are RMS values.

Parker Hannifin, O-Ring Handbook — Design Chart 4-3: O-Ring Face Seal Glands — p. 1

Tabletop: A fly-cut or turned finish on the chamber lid seat should be specified/checked to 16 RMS; a rougher face is a common reason a 1e-6 Torr system stalls in the 1e-5s.

For External Pressure (inward pressure direction) dimension the groove by its inside diameter (Hi) and width: (H)i = Mean I.D. of O-ring

Parker Hannifin, O-Ring Handbook — Design Chart 4-3: O-Ring Face Seal Glands — p. 1

Tabletop: For an evacuated chamber atmospheric pressure pushes the ring inward, so the groove ID (not OD) is the controlled dimension when laying out the lid groove.

care being taken to insure that there are no machine or tool marks perpendicular to the seal... The ideal surface finish for any vacuum seal flange has a circular lay

Parker Hannifin, O-Ring Vacuum Sealing, Catalog 5705B (1998) — p. 5

Tabletop: Face the lid seat on a lathe (concentric lay) rather than fly-cutting or hand-sanding radially; never sand a groove crosswise to remove a blemish.

External leak checking with helium should begin at the top of the chamber; only a small helium flow rate is necessary... Welds and seals are the most common leak sites

O'Hanlon, A User's Guide to Vacuum Technology, 3rd ed. (2003) — p. 467-470

Tabletop: Helium rises - spraying from the bottom up floods every joint at once and destroys localization on a chamber with many ports.

Vacuum rated to 1 x 10-8 Torr (better suited to 1 x 10-6 Torr). Temperature rating is dependent on which elastomer o-ring is used (usually 150C)

Bertolini, Accelerator Vacuum and Mechanical Engineering — USPAS course, UCRL-MI-201847 (2004) — p. 443-446

Tabletop: Matches the reference machine's observed 1e-6 range with Viton - it is the natural floor of an all-elastomer system; a CF port or two on a next machine (gauge, RGA) buys headroom cheaply.

Avoid phrases like; leak tight, vacuum tight, good to 10-8 Torr, good for ultrahigh vacuum, etc.

Bertolini, Accelerator Vacuum and Mechanical Engineering — USPAS course, UCRL-MI-201847 (2004) — p. 456-464

Tabletop: When farming out a next machine's welds or buying used hardware, write the acceptance spec as a number (e.g. no single leak >1e-9 atm-cc/s He) - 'vacuum tight' is unenforceable.

Mechanical Cleaning; Degreasing or Solvent Cleaning; Detergent Cleaning; Chemical Etch; Electrolytic Polishing; High Pressure Spray; Bake-out

Bertolini, Accelerator Vacuum and Mechanical Engineering — USPAS course, UCRL-MI-201847 (2004) — p. 497-513

Tabletop: Scaled down: acetone wipe, hot detergent wash, DI rinse, N2 or oven dry, gloves-only handling afterward gets most of the professional benefit for chamber internals.

A virtual leak is a volume of trapped atmospheric gas that leaks into the vacuum vessel through holes or cracks that do not go all the way through the vessel wall. [Examples:] Unvented Screw, Two Welds in Series, Unvented Double O-rings

Bertolini, Accelerator Vacuum and Mechanical Engineering — USPAS course, UCRL-MI-201847 (2004) — p. 59-63

Tabletop: Every internal socket-head screw in the next machine (dee supports, ion source mounts) needs a vent hole, a slotted thread, or a vented washer; a slot machined in the O-ring groove floor serves the same purpose.

Seam welds are continuous, with welding only on the atmosphere side. The internal braces are stagger welded to keep virtual leaks at a minimum.

Ramler & Parker, The Argonne 60-Inch Cyclotron — ANL-5907 (1959) — p. 7

Tabletop: Standard practice worth enforcing on any welded chamber or fitting on a next machine: no vacuum-side seal welds, no closed pockets.

preliminary washing of the parts in CCl4 is recommended to remove organic matter

Wouters, General Recommendations for Design of Small Cyclotrons — UCRL-476 (1949) — p. 9

Tabletop: Directly applicable (use modern solvents, not CCl4); degrease every part of a next machine that sees vacuum.

Steel supporting rods allow thin top and bottom plates to minimize thickness

Baumgartner & Heuer, The Cyclotron Kids 14-Inch Accelerator (2010) — p. 6-7

Tabletop: Every millimeter of lid steel is a millimeter of magnet gap; internal posts (placed outside the beam plane) let the builder close the next machine's gap without a lid that dishes under vacuum.

A 2.54 cm thick ring with an outer radius of 9.9 cm and an inner radius of 8.5 cm was milled from 6061 T6 aluminium ... Ports were made in the chamber wall using ten KF-16 flanges, which were secured using Hysol Loctite 1C vacuum epoxy

Yuly, The Houghton College Cyclotron: a Tool for Educating Undergraduates — Cyclotrons 2013, WE1PB01 (2013) — p. 2

Tabletop: A complete, copyable chamber spec for an 8-inch-pole machine, including the epoxy-in-flange trick that avoids welding.

continuous square rubber gaskets located in grooves in the faceplates of sufficient cross section to accommodate the entire gasket under pressure. The resulting metal-to-metal contact ... has proved very satisfactory.

Livingston & Boch, The Oak Ridge 86-Inch Cyclotron — ORNL-1196, OSTI 4357145 (1952) — p. 41

Tabletop: Directly applicable to a next machine's chamber lids and faceplates; grooved captive gaskets beat flat sheet gaskets for repeatable sealing and alignment.

As we tighten the rest of the bolts the joint is further compressed, and the previously tightened bolts tend to relax and lose some of their preload. In some cases, this can virtually eliminate our bolt tension.

Fastenal, Technical Reference Guide, Rev. 9 (2005) — p. 26

Tabletop: On the next machine's lid, a single-pass tightening leaves the first-torqued sector under-clamped and is a classic cause of an O-ring leak that 'moves' with each reassembly.

when an extra-shallow gland is desired in order to increase the squeeze, it must be made wide enough to accomodate the full O-ring volume.

Parker Hannifin, O-Ring Vacuum Sealing, Catalog 5705B (1998) — p. 1-2

Tabletop: If a next machine's grooves are cut for 30% squeeze, groove cross-section area must still exceed ring cross-section area - check fill before cutting.

Radius R is CRITICAL. Insufficient radius will potentially cause damage to the O-ring during installation, while excessive radius may contribute to extrusion.

Parker Hannifin, O-Ring Vacuum Sealing, Catalog 5705B (1998) — p. 10

Tabletop: Worth it for a hinged or frequently-removed lid where the ring falls out during assembly; otherwise plain rectangular face grooves are cheaper and more tolerant.

after the welding, the bottom plate contracted so much that it bent the whole frame out of shape... seal the bottom plate against the frame using a flat Viton ring.

Baumgartner, The Cyclotron Kids' 2 MeV Proton Cyclotron — Cyclotrons 2013, WE1PB05 (2013) — p. 2-3

Tabletop: A fabrication trap the builder can skip entirely: o-ring/flat-gasket both lids, weld nothing flat and thin.

The maximum volume of the O-ring should never surpass the minimum volume of the gland... the O-ring volume does not exceed 95% of the gland void.

Apple Rubber Products, Seal Design Guide — p. 14-16

Tabletop: Check fill arithmetic including worst-case ring tolerance before machining; Viton heated by RF or magnet proximity expands ~16e-5/C and needs that free volume.

a finish of 32 micro-inches RMS is preferred... Static seal cross sections are generally compressed from 10% to 40%, whereas dynamic seals are from 10% to only 30%.

Apple Rubber Products, Seal Design Guide — p. 19, 61

Tabletop: For a rotating or sliding shaft feedthrough (target manipulator), back off to <=30% squeeze and a 16-32 RMS shaft finish, or friction will shred the ring.

Do not use a lubricant composed of the same material as the O-ring because 'like' will dissolve 'like.' For example, a silicone lubricant should not be used with a silicone O-ring.

Apple Rubber Products, Seal Design Guide — p. 20, 109

Tabletop: Silicone vacuum grease on Viton is fine; silicone grease on a silicone ring (or hydrocarbon grease on Buna-N) slowly destroys it.

In order to use a standard round O-ring, the inside corner radius of the groove should not be less than three times (3X) the O-ring cross-section diameter.

Apple Rubber Products, Seal Design Guide — p. 84

Tabletop: Directly applicable to a racetrack or rectangular lid/port on a next machine: a 1/8 in. cord ring needs >=3/8 in. corner radii or it will bunch and leak at the corners.

304L SS, most commonly used in vacuum, a little more expensive... Joint design is critical from vacuum, metallurgical and distortion standpoints. Cleanliness is essential.

Bertolini, Accelerator Vacuum and Mechanical Engineering — USPAS course, UCRL-MI-201847 (2004) — p. 355-360

Tabletop: For a next machine's chamber welds specify 304L filler and pipe where possible; carbide precipitation in plain 304 welds is a known source of micro-leak porosity.

a lid with radius 10 centimeters and thickness of 3.5 millimeters would undergo less than 1 mm of deflection when covering a chamber with internal pressure of 1e-3 Torr

Dewan, Design and Construction of a Cyclotron Capable of Accelerating Protons to 2 MeV — MIT thesis (2007) — p. 12

Tabletop: Gives the builder the actual formula for trading a next machine's lid thickness against magnet gap - a few mm of 7075 plate suffices at 8-12 inch chamber diameter if the edge is well supported.

the VTO box and obround are mounted on a motor-driven carriage which operates on a rail system. This permits the removal of the dee heads... to facilitate maintenance.

Ramler & Parker, The Argonne 60-Inch Cyclotron — ANL-5907 (1959) — p. 6-7

Tabletop: At tabletop scale this means: chamber slides out of the gap, dee removable through a lid, pump cart disconnectable - the difference between a research tool and a sealed monument.

The limit at the entry is set by the dr between successive turns at this radius ... it is desirable to have adjustable controls on deflector spacing and location which can be trimmed empirically.

Livingston & Blewett, Particle Accelerators (1962) — p. 181-183

Tabletop: With 2.6 kV/turn on 160 keV, the reference machine's turn spacing at extraction is ~1.6% of R (~1.3 mm at 3.2 in) - build the septum mount with mm-scale radial adjustment.

the septum is formed of two strips of tungsten, 0.020 in. thick and 12 in. long and with the edges spaced 1/8 in. apart. Each strip is silver-soldered to a copper bar bent to the correct curvature.

Livingston & Blewett, Particle Accelerators (1962) — p. 184

Tabletop: At the reference machine's microamp/keV beam power the thermal problem vanishes, but the slotted-septum geometry still maximizes transmitted current into the channel.

By having only three faces any one face is completely shielded from the material sputtered from that which is in the beam

Oliphant & Rutherford, Experiments on the Transmutation of Elements by Protons (1933) — p. 262

Tabletop: A boron target plus a blank plus a calibration face on one rotatable holder would let the builder switch targets and measure background without venting.

Thread lubrication is one of the most effective measures to lessen the potential for galling... Heat contributes significantly to thread galling.

Fastenal, Technical Reference Guide, Rev. 9 (2005) — p. 8

Tabletop: Every stainless bolt into the stainless chamber flange gets anti-seize (outside the vacuum) or silver/moly plating (inside); one galled lid bolt can strand the whole chamber.

The grid should be made from tantalum or tungsten wire and be fusion or resistance welded.

Hull, The Farnsworth/Hirsch Fusor — The Bell Jar, Vol. 6 No. 3/4 (1997) — p. 5-8

Tabletop: Applies to the reference machine's chimney slits, puller edges, and beam stops: anything the beam or arc touches for long runs should be refractory metal with welded, not soldered, joints.

With conventional steel nut and bolt materials, a length of engagement of about one nominal diameter of the bolt is typical. A longer thread length engagement will be needed when dealing with tapped holes in soft material.

Fastenal, Technical Reference Guide, Rev. 9 (2005) — p. 14

Tabletop: Tapped holes in aluminum lids or pole pieces need 1.5-2d of thread or inserts; a stripped hole in the finished chamber is far costlier than a longer bolt.

Torque = K x d x F... F = 75% of bolt material proofload for standard bolts... even perfect input torque can give a variation of preload by as much as 25 - 30 %.

Fastenal, Technical Reference Guide, Rev. 9 (2005) — p. 25-26

Tabletop: Gives defensible torque numbers for lid bolts and magnet clamp bolts; critically, if a bolt is lubricated but torqued to the dry-K table value, preload can double and snap the bolt.

we used an installation torque of 70 ft-lbs to obtain a clamp load of 9000 lbs... By the fourth installation, we required 145 ft-lbs to reach a clamp load of 9000 lbs.

Fastenal, Technical Reference Guide, Rev. 9 (2005) — p. 30

Tabletop: Lid bolts cycled dozens of times per year drift far from any torque table; for repeatable magnet-gap or flange clamping, replace nuts periodically or control by turn-of-nut instead of torque.

The project was a long and laborious one, but the efforts were well-rewarded when the first beam was obtained three years later, in the spring of 1957.

McGuire, The Iowa State University 1.5 MeV Undergraduate Cyclotron (1961) — p. 3

Tabletop: Schedule reality check for a next machine and for any educational-accelerator product plan.

TOTAL: $128500. Who has >$125k to blow on a very modest strawman small particle accelerator?

Niell, Effective Scientific Equipment Procurement Strategies: Building on a Budget (2010) — p. 2-3

Tabletop: Calibrates the next machine's budget: every subsystem the builder does not scrounge or fabricate costs thousands new, so design decisions should follow what surplus actually offers.

Cost: Can spend no more than $400. Performance: Want to measure 40MHz sinewaves... Function: Must be in calibration, and nearly bombproof

Niell, Effective Scientific Equipment Procurement Strategies: Building on a Budget (2010) — p. 7-10

Tabletop: A disciplined method for the next machine's shopping list: define B-field, vacuum, and RF numbers first, then match each to the cheapest vendor tier whose reliability the subsystem can tolerate.

The voltage divider allowed use of a low voltage meter by tapping the divider string at a 10,000 part fraction of the total voltage drop.

Kovalchick, Deuterium Fusion Using Inertial Electrostatic Confinement (2012) — p. 18-19

Tabletop: Directly reusable for the reference machine's dee/extraction HV monitoring; a divider-plus-panel-meter is safer and more trustworthy than reading the supply front panel.

One might choose a 12 kV, 60 mA neon sign transformer and use 2 - 12 kV microwave oven diodes... Never apply full voltage immediately to the fusor!

Hull, The Farnsworth/Hirsch Fusor — The Bell Jar, Vol. 6 No. 3/4 (1997) — p. 5-8

Tabletop: A scrounger-grade current-limited HV architecture suitable for the reference machine's source-conditioning and glow-discharge cleaning supplies.

If the task is to obtain an average field with a value of the field decay index n close to constant for all radii, then the axial gap g can vary in accordance with the expression

Smirnov, The Cyclotron and Its Modeling — Phys. Part. Nuclei 52 (2021) — p. 49

Tabletop: A one-line pole-taper recipe for the builder tool: pick n (e.g. 0.02-0.2), machine the gap to this power law, verify in FEMM.

An angle kick of typically 50 to 100 mrad is provided. The inner electrode, septum, is at earth potential. At the entrance it has a thickness of a few tenths of a mm, increasing to several mm at the exit.

Botman & Hagedoorn, Extraction from Cyclotrons — CAS, CERN 96-02 (1996) — p. 14

Tabletop: At 350 keV a 100 mrad kick over 10 cm of arc needs only ~5.6 kV/cm - about 2.8 kV across a 5 mm gap; at nanoamps the septum needs no cooling (~0.1 mW).

a criterion for the product of electric field E and potential V for a cyclotron deflector in order to avoid electric discharges: VE < 1.5 104 (kV)2/cm. The maximum sustainable voltage in a magnetic field is 20-30% lower.

Botman & Hagedoorn, Extraction from Cyclotrons — CAS, CERN 96-02 (1996) — p. 14

Tabletop: A 3-5 kV, 5-10 kV/cm tabletop deflector sits ~300x below this limit; the practical amateur ceiling is set by feedthrough and edge-radius engineering (the ~26 kV/cm working rule), not bulk breakdown.

At HV edges, electric field lines become so dense that breakdown becomes a major concern. Aluminum=290 kV/inch ... We settled on a minimum radius of R=.1875 inches ... Emax=170 kV/inch

Ponter, Beam Energy Measurements with a New HV Deflection System and Ion Source Upgrades on the Rutgers 12-Inch Cyclotron (2010) — p. 8

Tabletop: Direct amateur precedent: a 1 T / 472 keV university tabletop deflector at 28-32 kV; a next machine needs only ~1/10 the voltage, so generous edge radii make sparking a non-issue.

~0.1 Joules at 30 kV ... ~0.4 Joules at 30 kV ... The bottom plate and deflector electrode - no pitting on the electrode noticed.

Ponter, Beam Energy Measurements with a New HV Deflection System and Ion Source Upgrades on the Rutgers 12-Inch Cyclotron (2010) — p. 43

Tabletop: Rutgers arced a 30 kV-rated feedthrough run at 35 kV and had to rebuild with the feedthrough inside vacuum plus a corona adapter - rate a next machine's feedthrough 2-3x over operating voltage.

For DR = 0.1R: Va = 47,000 volts ... A typical figure, used in the MIT cyclotron, is a DR of 0.15R. ... The deflector gap is usually tapered.

Livingston & Blewett, Particle Accelerators (1962) — p. 163-166

Tabletop: Scaling by 2T: a next machine at 350 keV needs ~1/45 of MIT's voltage for the same geometry ratio - about 1-3 kV across a 3-5 mm entry gap, rising if a faster peel (larger DR) is wanted.

generate a plasma discharge that yields a continuous 1 mA beam of positively charged hydrogen ions at 1 mTorr of pressure. This operating condition requires 5.4 kV and 32.4 W of power.

Rovey, Ruzic & Houlahan, Simple Penning Ion Source for Laboratory Research and Development Applications (2007) — p. 1-3

Tabletop: Existence proof that mA-class hydrogen PIG output needs only tens of watts and home-shop fabrication (spot-welded sheet anode, epoxied alumina tubes). The axial-extraction geometry differs from a cyclotron chimney but the discharge economics transfer directly.

The chamfer in both of the slit chimneys tested was 10 [deg] ... was 0.010" deep (out of a 0.020" thick chimney wall) leaving a 0.010" [land]

Forringer, Phase Space Characterization of an Internal Ion Source for Cyclotrons — MSU dissertation (2004) — p. 77, 84, 95-97

Tabletop: These are the actual machining callouts for a chimney a home shop can cut — thin land so the slit doesn't collimate away the beam, chamfer opening outward toward the puller.

The cathode anode gap was between 0.075" (1.9 mm) and 0.150" (3.8 mm), and is not a critical parameter for the source's operation.

Forringer, Phase Space Characterization of an Internal Ion Source for Cyclotrons — MSU dissertation (2004) — p. 29

Tabletop: Generous mechanical tolerance — the chimney stack-up doesn't need precision fitting. But take the cooling warning seriously even at 100 W-class arc power; provide a conduction path sized for continuous arc wattage or plumb water.

the properly aligned configuration produces significantly more secondary emission electrons ... with the anode rotation angles from -0.2 to -1.5 degree, more than 50% H- beam can be extracted through pullers

Mu et al., Simulation of Electron Behavior in PIG Ion Source for 9 MeV Cyclotron (2015) — p. 4-6

Tabletop: Two different tolerance classes: build the chimney concentric (pin the cathode discs to the bore, machine in one setup), and provide an external rotational adjustment of the source stalk of ~ +/-2 deg with sub-degree feel for slit-to-puller aiming — set-and-lock, in-vacuum.

A series of studies were made on a model magnet with poles 2 inches in diameter. This could be changed quickly and cheaply to give rough data over a wide range of parameters.

Creutz, Design and Construction of Synchro-Cyclotron — NYO-780 (1950) — p. 7

Tabletop: General magnet practice, fully transferable - a next machine's pole/yoke/shim geometry can be optimized on a small bolt-together model before buying full-size steel.

The deflection of the poles under the magnetic load was found to average .002 to .004 inches for the model.

Creutz, Design and Construction of Synchro-Cyclotron — NYO-780 (1950) — p. 9

Tabletop: Directly applicable - mil-level gap closure at 0.6 T shifts field and n(r); shim and map the next machine at operating excitation, not cold.

A final pair of model poles was machined out of the steel forgings actually used for the full-scale magnet poles. The results were satisfactory, and the design was frozen.

Creutz, Design and Construction of Synchro-Cyclotron — NYO-780 (1950) — p. 10

Tabletop: Transferable principle - steel-to-steel permeability variation is real; test a next machine's shim stock from the same material lot as the poles.

The machining of the pole tip was held to +/- .0025 inches on almost all dimensions.

Creutz, Design and Construction of Synchro-Cyclotron — NYO-780 (1950) — p. 11

Tabletop: Directly applicable - a few-mil pole tolerance is achievable in a good hobby/job shop and is what the field uniformity budget assumes.

Glass tape is inserted along all metal seams to prevent weld-flash from entering the can.

Creutz, Design and Construction of Synchro-Cyclotron — NYO-780 (1950) — p. 14

Tabletop: Directly applicable craft rule for any welding or brazing done near a next machine's coil insulation or on the coil case.

Each assembly was leak-tested with a helium mass spectrograph after manufacture.

Creutz, Design and Construction of Synchro-Cyclotron — NYO-780 (1950) — p. 20

Tabletop: Directly applicable - bench-test each next-machine spool, duct, and feedthrough with a helium sniffer (or pressure/soap plus rate-of-rise) before it disappears into the stack.

results now indicate that four 880's will suffice, while the data from the three-fourths scale model had indicated that six would be necessary.

Creutz, Design and Construction of Synchro-Cyclotron — NYO-780 (1950) — p. 29

Tabletop: Transferable caution - stray C, proportions and device parameters do not scale cleanly; validate a next machine's dee voltage vs drive on the real geometry, treating models as guides.

good contact is established by the use of strips of thin soft copper sheet backed by foam rubber pads.

MacKenzie et al., Design of the Radio-Frequency System for the 184-inch Cyclotron — UCRL-64 (1948) — p. 10

Tabletop: Directly applicable - the cheap 1948 equivalent of RF finger stock for every removable panel, dee-stem clamp, and line cover on a next machine.

Over 50 kilovolts rf could be developed across the insulator at 13 mc by a 5 kilowatt oscillator. Under the most severe test conditions, air blast cooling of the insulators was found necessary.

MacKenzie et al., Design of the Radio-Frequency System for the 184-inch Cyclotron — UCRL-64 (1948) — p. 13

Tabletop: Directly applicable - a bench quarter-wave resonator lets the builder soak-test a next machine's dee-stem insulators at full 5-13 kV RF with only tens of watts of drive.

For reasons of convenience, a quarter scale was chosen. The resonant frequency is then increased fourfold and all inductances and capacitances are reduced by a factor of four.

MacKenzie et al., Design of the Radio-Frequency System for the 184-inch Cyclotron — UCRL-64 (1948) — p. 14

Tabletop: Transferable method - a next machine's resonator can be prototyped at reduced scale with a VNA, remembering effective dee capacitance is not the static capacitance (500 vs 1000 pF on the 184-inch).

The evident discrepancy in transmission line length was eventually traced to a cumulative error of about two inches in various small errors in model dimensions.

MacKenzie et al., Design of the Radio-Frequency System for the 184-inch Cyclotron — UCRL-64 (1948) — p. 22

Tabletop: Directly applicable - give the next machine's resonant line/tank a deliberate tuning range (trombone section, tuning vane, trimmer C) instead of trusting calculated dimensions.

The care taken in insuring that only pure tension and compression forces would be applied was thus well justified.

MacKenzie et al., Design of the Radio-Frequency System for the 184-inch Cyclotron — UCRL-64 (1948) — p. 24

Tabletop: Directly applicable to a next machine's dee-stem standoffs and feedthroughs - arrange the support geometry (threaded rods, spherical seats) so ceramics never see bending or shear.

The horizontal joints are also rubber backed, but no particular care is necessary to insure contact as the current flow is parallel to the joint.

MacKenzie & Waithman, R.F. System for Frequency Modulated Cyclotron — MDDC-1045 (1946) — p. 6

Tabletop: Directly applicable enclosure craft - plan a next machine's panel seams along the RF current direction and spend the contact-strip effort only on the seams that cross it.

Polystyrene of this thickness used in this manner will stand over 15,000 volts DC and approximately 1500 volts r.f. provided the metal parts remain cool.

MacKenzie & Waithman, R.F. System for Frequency Modulated Cyclotron — MDDC-1045 (1946) — p. 8

Tabletop: Transferable construction recipe for homemade HV bypass/blocking capacitors in a next machine's RF chain (modern Kapton/PTFE substitutes upgrade the polystyrene).

bombarded with a large deuteron beam for about 1 to 3 minutes, removed from the tank and radioautographs were taken to determine where the beam was hitting.

Vale, 184-inch Cyclotron Vertical Beam Oscillations in the Region of 82-inch Radius — MDDC-984 (1947) — p. 3

Tabletop: Copy the C-target geometry but read it with phosphor screen or dental X-ray film instead of activation; a set of slotted witness targets at different radii gives the whole vertical envelope in a few runs.

There was considerable sparking between the HV electrode and the .002 inch copper foil. The copper foil was warped badly ... The 0.002 inch copper foil supported in this manner is not suitable for this job.

Sewell, 184″ Cyclotron: Vertical D.C. Electrostatic Deflector — MDDC-1051 (1947) — p. 2

Tabletop: A next machine's septum should be thicker (>= 0.010 in), tensioned, or heat-sunk at both edges; conditioning sparks are inevitable and each one dumps its energy into the nearest thin edge.

Construction started 1940. Completion date July 1941 ... Total cost $5000 initial, $5000 improvements.

Howard, Cyclotrons and High-Energy Accelerators, 1958 — ORNL-2644 (1958) — p. 166

Tabletop: Scope calibration: a garage-adjacent team building a 2-4 MeV, 16-27 in machine was normal in this era; a next machine at 0.3-1 MeV on 8-in-class iron is historically a modest, well-precedented project.

no discoloration or other indication of heating of the contacts, despite routine operation to 110 A/in and occasional operation to higher current densities

Osterlund & Smythe, A Cyclotron Power-Amplifier RF System Using a 4CW50,000C/8350 Tetrode — COO-535-543 (1963) — p. 8

Tabletop: A tabletop coaxial resonator tuning short carries far less current, so 110 A/in is a generous ceiling - but the recipe (thick fingers, positive clamping, plated surfaces, cooling on both sides of the joint) is the proven pattern for any movable-short tuner.

The minimum radius of curvature of the high-voltage electrode should be large enough to prevent appreciable field-gradient magnification. In practice, the minimum radius should be no less than about half a gap.

Smith & Grunder, Electrical Design of Electrostatic Deflectors for Sector-Focused Cyclotrons — UCRL-10654 (1963) — p. 17

Tabletop: Direct machining rule - for a next machine's 3-mm deflector gap, radius every HV edge to at least 1.5 mm and polish.

At the smaller gaps the electrode vibrated like a tuning fork in a tuning-fork oscillator.

Smith & Grunder, Electrical Design of Electrostatic Deflectors for Sector-Focused Cyclotrons — UCRL-10654 (1963) — p. 17

Tabletop: Very much in reach of amateur trouble - a small cantilevered electrode has low mass and compliance. Support a next machine's deflector bar on insulators at both ends and check the deflector voltage on a scope for slow oscillation buildup.

Each circuit board consists of 100 Unitrode, Type UT71, silicon diodes connected in series. Each diode is shunted by a 250-pF, 500-V, ceramic capacitor to divide the inverse voltages equally.

Smith, Deflector Power Supply for Sector-Focused Cyclotrons — UCRL-10655 (1963) — p. 10

Tabletop: The 1963 'inexpensive silicon diodes + TV ceramic caps' recipe is today a standard multiplier stack; keep the two design features that matter - per-diode grading capacitors and high drive frequency (small energy per stage, fast regulation).

The spacing between boards is about 2 in. and provides a nominal maximum design gradient of 10 kV per in.

Smith, Deflector Power Supply for Sector-Focused Cyclotrons — UCRL-10655 (1963) — p. 10

Tabletop: A conservative, corona-quiet air-gradient number for amateur HV column layout; at 60 kV total a next machine's stack wants ~6 in of creep/clearance headroom or potting/SF6-free oil.

the deflector oscillators are located close to the magnet yoke of the cyclotron in a field of about 150 G, magnetic shields had to be put over the 4CW2000 oscillator tube and the 3D22.

Smith, Deflector Power Supply for Sector-Focused Cyclotrons — UCRL-10655 (1963) — p. 19

Tabletop: Modern solid-state supplies mostly shrug at 150 G, but CRT-style meters, vacuum gauges, photomultipliers, and any remaining tubes near a next machine's yoke need the same treatment; mild steel is enough at this level.

Approximately ninety percent of the total power input to the system is eventually dissipated in the transformer cores as heat. At rated operating levels this loss is approximately 500 watts.

Kerns et al., High Voltage Pulser for 184-inch Cyclotron Electric Deflector — UCRL-95 (1948) — p. 12

Tabletop: Not needed for a CW deflector, but the de-aerated-oil corona cure, the 3x overvoltage proof test, and the interlaminar-voltage failure mode are transferable HV-construction craft for any oil-insulated amateur component.

a bracket has been attached to the west side of the liner which places the ion source one inch below the center of the magnetic field. This arrangement insures that the position will be the same from run to run.

Howard (ed.), Electromagnetic Research Division Quarterly, period ending 31 March 1952 — ORNL-1339 (1952) — p. 10

Tabletop: Cheap and directly imitable — once the optimum source position is found by scanning, capture it in a hard registration feature so it survives every source rebuild; grounding the support also kills a stray RF-heating path.

The alignment of the source with the magnetic field is extremely critical, as was expected, and makes it necessary to provide for external adjustments of the ion source.

Howard (ed.), Electromagnetic Research Division Quarterly, period ending 30 June 1952 — ORNL-1345 (1952) — p. 10

Tabletop: Strong design input for a next machine: budget at least one live source degree of freedom (rotation or z) through the vacuum wall — both ORNL machines retrofitted it after finding the optimum could not be reached blind. On the reference machine, even a graduated feedthrough beats vent-adjust-pump iteration.

moving the 8 inch plug to 5.5 inches from the valley floor and to extend the caps to a length of 3 1/2 inches. These caps saturate at high levels, but fill in the central "hole" at low fields.

Jungerman, Kibbe & Peek, Central Region Studies for Incorporating an Axial Ion Source in the Davis 76-in. Cyclotron — UCD-CNL-49 (1966) — p. 6

Tabletop: Deliberately-saturating iron as a field-programming element is a trick FEMM models well — for a next machine's central plug or shim stack, a piece sized to saturate at the main operating point gives low-field correction "for free" without trim windings.

The contour of the shim when the steel surface is not an equipotential is best determined experimentally. An approximate shim can be put on a pole which otherwise has its final form.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 8

Tabletop: Directly the next machine's shim program - FEMM replaces some iterations, but finite permeability and saturation mean the last passes happen on the bench with a probe map, exactly as NYO-780 (p.7) did with its bolt-together model magnets. Cite both.

In a high-current low-voltage coil, insulation is required only to maintain mechanical separation of the conductors.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 25

Tabletop: Argues for the classic amateur choice - few turns of heavy bar/strap at high current with generous cooling passages beats many-turn fine-wire coils on space factor, insulation risk, and pumping pressure.

A second type of coil which is more attractive, when the coil must be wound at the cyclotron site, is a flat-wound helix.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 26

Tabletop: Directly a garage-scale construction technique - cut flat copper sectors, stack into a helix with brazed/bolted joints (see the 10 kA/cm2 joint rule), no winding mandrel needed.

One square centimeter of metallic contact distributed over the joint will carry 10,000 amps with negligible resistance and temperature rise.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 32

Tabletop: Frees a builder from soldering anxiety on bus joints - a clean bolted lap of a few cm2 is electrically invisible at the tens-to-hundreds of amps any amateur coil carries.

opened automatically when the mechanical pump is shut down so as to break the vacuum in the line and prevent the pump oil from backing up the line.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 140

Tabletop: Both bites transfer verbatim to a garage system - an automatic vent on the roughing pump (or a check valve) prevents the classic oil-suckback chamber contamination, and bellows belong in vertical runs.

welding neck flanges with double O-ring gasket grooves machined in a standard flat face flange and provided with a pump-out connection between the two gaskets.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 141

Tabletop: The double-O-ring-with-interspace-pumpout trick is worth stealing for any large troublesome amateur flange (chamber lids especially) - the interspace can be sniffed for leak location or held at rough vacuum to null permeation across the inner ring.

The crystal oscillators, Nos. 3 and 5, will maintain a constant frequency within one part in 10,000.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 169-170

Tabletop: The stabilization pattern transfers even where the parts are now silicon - put the reference AND the analog discrimination components in one controlled thermal box; the filter drifting is as fatal as the oscillator drifting.

The fairly low efficiency, 27 per cent, indicates that it would be desirable to go to six type-880 tubes in the final model, especially since power-supply capacity is available for the additional tubes.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 162

Tabletop: The transferable method rule - prototype the next machine's dee/stem/liner as a cheap scale model (or full-scale mockup, given the small size) and measure resonance, Q and parasitics before final fabrication; NYO-780 p.29ff records the same practice. Cite both.

It was found necessary, however, to use a covered carbon boat both to reduce the radiation cooling of the boron and to prevent scattering of the material during the heating.

Hoke & Newman, Self-Supported Cyclotron Targets of Boron and Magnesium — ORNL-3021 (1961) — p. 6

Tabletop: Boron is among the worst common elements to evaporate (needs ~2000 C+, attacks refractory-metal boats); carbon-rod stock is cheap and machinable with ordinary tooling. This is the boat design to copy for making B-11 films for the next machine's B11(p,alpha) experiment — the recipe is isotope-blind.

by passing a current of about 280 amp at 8 volts through the boat, a sufficiently high temperature was reached (white heat) to vaporize the boron.

Hoke & Newman, Self-Supported Cyclotron Targets of Boron and Magnesium — ORNL-3021 (1961) — p. 6

Tabletop: Numbers verified on the page image. Scope honestly: this is EVAPORATION producing research-grade ug/cm2 self-supported films — exactly right for a p+B11 cross-section or resonance-yield measurement, and NOT the route to a thick sputtered/pressed target for a maximum-alpha-yield demo. 2.2 kW low-voltage supply and a 1e-5 torr bell jar are amateur-reachable.

The boats are useful for only two evaporations at most since the slot rapidly becomes clogged with boron carbide.

Hoke & Newman, Self-Supported Cyclotron Targets of Boron and Magnesium — ORNL-3021 (1961) — p. 6

Tabletop: Hot boron converts the carbon boat itself to B4C — no boat material choice fixes this, it is stoichiometry. Plan the enriched-B11 evaporation campaign around several pre-machined boats and one plate per boat-load rather than debugging mid-run.

the method found successful here was to float the boron off the plate with warm tap water.

Hoke & Newman, Self-Supported Cyclotron Targets of Boron and Magnesium — ORNL-3021 (1961) — p. 6

Tabletop: The entire film-recovery toolchain is kitchen-grade (dishwasher detergent, tap water, glass plates) — the skill is in the sequence, all of which is written down here (pp.6-8). Practice on natural boron before spending enriched B-11.

Stronger double films, which proved to be much easier to make, were made by bringing the frame up in the middle of the film. The film then folded over the frame

Hoke & Newman, Self-Supported Cyclotron Targets of Boron and Magnesium — ORNL-3021 (1961) — p. 8

Tabletop: For a next machine's B11(p,alpha) internal-target experiment a 50-100 ug/cm2 film costs ~2-4 keV of proton energy loss at 170 keV — thin enough to sit on or near the 675-keV-resonance tail measurements' energy-definition budget while being mechanically survivable. Double-fold is the practical sweet spot.

increasing the current slowly over a period of 10 to 20 minutes so that the outgassing can occur quietly.

Hoke & Newman, Self-Supported Cyclotron Targets of Boron and Magnesium — ORNL-3021 (1961) — p. 9

Tabletop: Three generalizable tricks for any future target work — sacrificial carbon parting layers under fragile or reactive films, slow-ramp outgassing before full evaporation power, and a cheap glass hood (lantern-slide covers) so expensive enriched material can be scraped back and reused.

Representatives of the steel industry were consulted to determine the size of forging of the required shapes that could be practicably produced.

Oak Ridge National Laboratory, A Proposal for the Mc² Isochronous Cyclotron — ORNL-3540 (1963) — p. 136

Tabletop: Scale-free: for a next machine this reads 'call the waterjet/plate supplier before freezing the pole drawing' — same move as TID-454's cost-driven magnet design.

The estimate of $0.35 per pound for the finished magnet appears reasonable when compared with the unit price of $0.26 per pound paid for another large magnet at the Laboratory.

Oak Ridge National Laboratory, A Proposal for the Mc² Isochronous Cyclotron — ORNL-3540 (1963) — p. 245

Tabletop: Scale-free estimating hygiene: their App. F traces $11.5M to named suppliers; a next machine's BOM should likewise tie each line to a quote, a catalog page, or a reference machine receipt — and explain deltas ('more complex machining, more waste metal').

The method of brazing is considered unsatisfactory because of the extreme probability of leaving large flux inclusions between the beryllium metal and the aluminum base, which would seriously impair heat transfer.

Howard (ed.), Electromagnetic Research Division Semiannual, period ending 20 March 1953 — ORNL-1531 (1953) — p. 17

Tabletop: The corpus's targetry shelf is thin - this is a concrete bonded-target recipe. For a next machine's boron/beryllium targets on copper or aluminum backing, flux-free vacuum (or controlled-atmosphere) brazing with a thin Al-Si interlayer is the proven route to full-area thermal contact.

the magnet pole faces (tank walls) are being ground with a portable grinder to provide a very uniform magnetic field, as near +/- 0.01% as possible. This will then provide a standard base for the various magnetic shim designs

Howard (ed.), Electronuclear Research Division Semiannual, period ending 20 March 1954 — ORNL-1670 (1954) — p. 20

Tabletop: For a next machine's shim development (5 G ~ 5 deg rf phase target): establish and map the unshimmed field to the best flatness attainable FIRST, so every FEMM-predicted shim is measured against a known zero rather than against an uncharacterized pole error. Also proof that hand tooling on installed poles was acceptable ORNL practice - no magnet disassembly required.

The liner, dees, and dee-stem housing are being fabricated by an outside contractor. The faceplates, dee stems, ion source, target probe, and vacuum system were fabricated locally

Howard (ed.), Electronuclear Research Division Semiannual, period ending 20 March 1954 — ORNL-1670 (1954) — p. 20

Tabletop: The three-report arc (1670 -> 1795 -> 1884) is this collection's cleanest outsourcing lesson - brazed/water-cooled vacuum parts are where contractors fail, and each failure costs a reporting period. For a next machine, buy simple machining, but keep brazing, leak-checking, and anything water-to-vacuum under your own torch, or specify inspection windows up front.

several leaks in very inaccessible locations have delayed final assembly. In order to repair the leaks in the internal water-cooling tubes it was necessary to cut windows through the sides of the dees.

Howard (ed.), Electronuclear Research Division Semiannual, period ending 20 September 1954 — ORNL-1795 (1954) — p. 19

Tabletop: If a next machine's dees carry water, route tubing so every brazed or welded joint can be reached, pressure-test the dee as a unit BEFORE it meets the liner, and treat a cut-window-and-reweld as a planned repair mode (it worked) - the recovery technique is as instructive as the failure.

Grinding and shimming of the tank walls to produce a flat magnetic field was continued. The magnetic field is now uniform to within 0.05%.

Howard (ed.), Electronuclear Research Division Semiannual, period ending 20 September 1954 — ORNL-1795 (1954) — p. 19

Tabletop: Calibrates expectations for a next machine - 5e-4 base-field uniformity is what sustained professional effort actually bought on 44-in. poles; set the shim budget assuming the ground pole delivers ~0.05% and the final trim to the 5-G target comes from shims, not from more grinding.

The pole tips are removable so that shims of any shape can be inserted readily.

Howard (ed.), Electronuclear Research Division Semiannual, period ending 20 September 1954 — ORNL-1795 (1954) — p. 19

Tabletop: For any next-machine shim-test rig (or a scaled FEMM-validation magnet), design for the measurement campaign - open sightlines for the Hall probe, pole tips that unbolt, gap oriented for jig access. ORNL judged these features worth 14.4 tons of model.

The whole dee system is supported by a cantilever mounting at the outer end of the dee stems. This mounting is supported on insulators in order to permit the application of a bias potential to the dees.

Howard (ed.), Electronuclear Research Division Semiannual, period ending 20 March 1955 — ORNL-1884 (1955) — p. 19

Tabletop: The mechanical execution of the 1663 insulate-for-bias rule - for a next machine, one stiff cantilevered dee-stem mount outside the field region, isolated by insulators, is simpler than distributed insulated supports and keeps the bias feed and rf geometry clean.

Morley Machine Company, Rochester, N.Y., produced milling cutters conforming to this equation ... Subsequent work has shown that circular arcs would have been satisfactory.

Bromley & Bruner, The Design of a Focusing and Analyzing System for the 27-inch Cyclotron Beam — NYO-3823 (1954) — p. 29

Tabletop: DIRECT money-saver, stated as an explicit lesson-learned footnote in 1954 and standard practice ever since. A next machine's quads (if built) can use round stock or FEMM-checked circular-arc tips; spend the FEMM time on end effects, not profile exactness.

The tips formed the top and bottom of the vacuum chamber of the magnet, while the side walls of the chamber were strips of non-magnetic stainless steel welded to the tips.

Alford, Bilaniuk & Hawrylak, Broad Range Spectrograph for Use with the Rochester 27-inch Cyclotron — NYO-9683 (1961) — p. 9

Tabletop: DIRECT construction pattern for any next-machine analyzer or spectrograph - poles-as-chamber eliminates the gap-wasting separate tank (the alternative Bromley rejected for his condenser on machining/gasketing grounds, nyo-3823 p.6). The anti-scattering baffles and the tenth-mil spacer discipline are the details that make emulsion-grade spectra possible.

The track has been rendered flat and horizontal to within 0.01" by a grinding machine rotated about the vertical post.

Alford, Bilaniuk & Hawrylak, Broad Range Spectrograph for Use with the Rochester 27-inch Cyclotron — NYO-9683 (1961) — p. 10

Tabletop: DIRECT machine-design lessons independent of scale: generate precision in place with the tool swung about the final axis (self-referencing, like Wilson's lapped dees), and use kinematic three-point support so a 5-ton instrument neither rocks nor requires a precision-flat floor. A next machine's scattering table wants exactly this architecture at 1/50 the size.

This region is a current maximum point at the highest frequency and most sensitive to volume or inductance.

Anderson, Half-Scale Model Tests on the Three Quarter Wave R.F. System — UCRL-31 (1947) — p. 10

Tabletop: On a small machine the dee-stem-to-chamber-wall clearance is the same critical region — it sets both the resonant frequency and where I^2R heating concentrates; machine it to drawing, do not shim it by eye.

Thermal neutrons are attenuated to about one-third of their initial flux by the first 10 cm of ordinary concrete. Therefore 2/3 of the activity produced by the neutrons would occur in this region. This makes it possible to design shielding with a row of concrete blocks on the inside.

Martin (ed.), Accelerator Radiation Protection — AD-755510 / USA-NLABS-TR-73-7, US Army Natick Laboratories (1972) — p. 84

Tabletop: The modular-block enclosure pattern already favored for product machines gets a second justification — the inner course doubles as the sacrificial activation layer, replaceable without demolishing the shield.

only heavy duty industrial type limit switches should be employed, avoiding light duty switches to insure durability and reliability.

Martin (ed.), Accelerator Radiation Protection — AD-755510 / USA-NLABS-TR-73-7, US Army Natick Laboratories (1972) — p. 149

Tabletop: BOM-level guidance for product machines — safety-rated (positive-opening) limit switches on lids/doors, not PCB microswitches, plus an interlock-test line item in the ops checklist (Cyclotron_procedures2 already has the pattern for vacuum; extend to safety chain).

one must be able to open these doors even after a loss of power. Some manual method of opening the door from inside and outside must be included in the design.

Martin (ed.), Accelerator Radiation Protection — AD-755510 / USA-NLABS-TR-73-7, US Army Natick Laboratories (1972) — p. 145

Tabletop: Scale-invariant egress principle — even an interlocked benchtop lid or a walk-in enclosure door must never imprison anyone on power loss; spring-return or manually liftable closures only.

a final "touch up" machining of these pieces, with the final iron in place on the basis of magnetic field mapping studies.

Rainwater et al., The Columbia University Nevis Synchrocyclotron Major Modification — NEVIS-189 / R-774 / CU-295 (1971) — p. 5

Tabletop: Fully transferable at any scale — design a next machine's shims and center plugs as bolt-on, pin-located pieces so field-map-driven iteration does not mean remaking the poles.

a "Ferrofluidic" vacuum seal having ~ 0.005 in. radial gaps in which a ferrite loaded low vapor pressure liquid is held by magnetic fields

Rainwater et al., The Columbia University Nevis Synchrocyclotron Major Modification — NEVIS-189 / R-774 / CU-295 (1971) — p. 10

Tabletop: Transferable component class, already commercial in 1971 and cheap today — the clean answer any time an accelerator mechanism (chopper, rotating target, variable capacitor) needs rotary motion through the chamber wall.

The capacitor housings have separate vacuum systems using turbomolecular pumps. RF feed through insulators separate them from the main cyclotron vacuum system.

Rainwater et al., The Columbia University Nevis Synchrocyclotron Major Modification — NEVIS-189 / R-774 / CU-295 (1971) — p. 10

Tabletop: Scales down well — a differentially pumped appendage for any mechanism (the reference machine already does this in spirit with the diff-pumped source region) keeps ion-gauge-clean chamber pressure honest.

the rotors are at low RF due to their < 0.010 in. high capacitance face gaps to ground

Rainwater et al., The Columbia University Nevis Synchrocyclotron Major Modification — NEVIS-189 / R-774 / CU-295 (1971) — p. 10

Tabletop: General lesson for any rotating RF machinery (choppers, tuners) at any power level; the rotating-capacitor FM tuner itself is synchrocyclotron-specific and does NOT transfer to a fixed-frequency tabletop machine.

a half-wave resonator permits the rotating capacitors to be located outside the main vacuum chamber for good shielding from both the magnetic field and radiation

Rainwater et al., The Columbia University Nevis Synchrocyclotron Major Modification — NEVIS-189 / R-774 / CU-295 (1971) — p. 10

Tabletop: The placement principle transfers — keep variable capacitors, trimmers, and drive mechanisms of a next machine's tank outside the pole gap and chamber where field, beam spray, and pumpdown cannot reach them.

This septum will use only 40 kW of power, a factor of four smaller than if the original thickness were kept to the end

Rainwater et al., The Columbia University Nevis Synchrocyclotron Major Modification — NEVIS-189 / R-774 / CU-295 (1971) — p. 13

Tabletop: A current-septum channel is beyond tabletop needs, but the geometric principle — septum thickness need only be minimal on the first intercepting turn — applies to any deflector septum or foil design on a next machine.

all support insulators have been designed so that they can be removed and replaced by remote handling tools.

Rainwater et al., The Columbia University Nevis Synchrocyclotron Major Modification — NEVIS-189 / R-774 / CU-295 (1971) — p. 12

Tabletop: At tabletop energies the driver is vacuum hygiene and downtime rather than dose, but the same design habit — most-likely-to-fail parts (insulators, filaments, septa) replaceable without major disassembly — is what the reference machine's filament-change experience already argues for.

the insulators will be subjected to about 3 times the rotor voltage to ground. This is because the long metal supports act as open transmission lines

MacKenzie, Preliminary Report on the “Three Quarter Wave” R.F. System for Frequency Modulated Cyclotrons — AECD-1850, University of California (1947) — p. 8

Tabletop: Check the electrical length of every support, cooling line, and instrument stalk inside the RF volume; a mechanically convenient standoff can sit at a voltage antinode and flash over at dee voltages its rating should easily hold.

End effects and bends in the line can cause this much variation. The conclusion is that there should be some possibility of varying the line length by a small amount

MacKenzie, Preliminary Report on the “Three Quarter Wave” R.F. System for Frequency Modulated Cyclotrons — AECD-1850, University of California (1947) — p. 11

Tabletop: Design connection lines and stubs with a sliding section or trombone worth a few percent of a wavelength; the calculation gets you to the right neighborhood and the adjustment does the rest.

The four PAA tuning capacitors are now coupled together by a heavy-duty chain driven by a single large servo motor with one translator. No trouble has been experienced since this modification.

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 24

Tabletop: Wherever two adjustments must stay matched (paired trimmers, symmetric shorting planes), a shaft, chain, or belt enforces the constraint by construction; independent actuators plus software matching is a standing failure mode.

the ion discharge aperture (0.09" x 0.50") was optically aligned with respect to the median plane of the cyclotron magnetic field and the electric field of the dee.

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 26

Tabletop: Source aperture height and tilt relative to the median plane set first-turn survival; make re-alignment after source maintenance a fixtured, measured step (scribe lines, a sighting jig, or a depth gauge) instead of trusting bolted repeatability.

with the coils energized to 3500 amperes, revealed a negligible deflection of the inner walls (about 0.002 inch) which eliminated the possibility of future collapse

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 27

Tabletop: Every conductor near the pole gap feels J x B; thin walls, septa, and coil leads need either stiffening or a measured demonstration that deflection at full excitation stays elastic - and motors, encoders, and anything with a magnetic circuit belong outside the fringe field.

we increased the flow rate to the 6949 tube plates from 42 gpm to 60 gpm by the addition of a 4-inch return pipe to separate the high pressure and low pressure water loops

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 29

Tabletop: When an amplifier cannot hold rated dissipation, check hydraulic head losses in shared manifolds before derating the tube; and duplicating the single-point-of-failure pump is a reliability purchase the outage ledger justifies.

perhaps the foil is damaged when there is radiation from a single spot only.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 240

Tabletop: A rotating target holder is 1950s-shop technology (motor, gears, O-ring feedthrough at ~2 rev/s); the same shaft can carry several targets so a fresh one rotates into the beam without breaking vacuum.

Rolling is by far the most conservative process with regard to material loss in preparing thin targets.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 18

Tabletop: The boron row of Table 1 is the direct answer for a B target: evaporation is the only listed route — 20-250 ug/cm2 self-supporting, 10-1000 ug/cm2 on a metal backing (boron is too brittle to roll). For thin-film evaporation recipes themselves cross-cite ORNL-3021; this table tells you which recipe book to open.

prevents the material from adhering to the rolls of the mill and enables a much thinner foil to be prepared

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 17

Tabletop: A jeweler's rolling mill plus shim-stock sandwich makes durable self-supporting metal targets (Table 1 shows most ductile metals reach 500-1000 ug/cm2 and up this way) — the natural route to robust backing foils and beam-stop targets.

evaporation efficiencies of only 1% are obtained.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 23

Tabletop: Budget isotope/material mass assuming ~1% of the charge lands on the substrate unless the geometry is engineered (tubular crucible, substrate close and directly above); crucible-evaporant chemistry (carbide formation, alloying) is chosen per material, not per convenience.

the ultimate measurement remains the direct mass determination of the target after it has been removed from the vacuum system.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 36

Tabletop: Treat the crystal monitor reading as a process gauge (right range, right rate), never the certified thickness; the crystal is heat-sensitive, so radiant load from the source shifts its frequency exactly when the reading matters most.

this method has proved to be a very reproducible process.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 27

Tabletop: Shrinking the source electrode to match the available material is the general move — sputtering scales down to gram and even milligram stock gracefully, unlike melt-based methods.

Zinc and cadmium condensed uniformly and with very high sticking coefficients.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 56

Tabletop: The crystal-structure-matching trick generalizes — when a film refuses to stick or beads up, a nanometer-scale nucleation layer of a structurally compatible metal fixes it; good sticking also raises tolerance to substrate heating during deposition.

the pressure gauge gives an indication of the rate of reduction

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 58

Tabletop: Lets a target come straight from a stable oxide powder with no separate metallurgy step, and the vacuum gauge doubles as the process monitor — no optical pyrometry needed.

the valve opened with a POOMPF and all the carbon substrates disappeared.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 274

Tabletop: Short-throw closed-boat geometry is how milligram quantities become usable targets (efficiency scales as 1/d^2); and every pump-down/vent of a chamber holding fragile foils needs a throttled soft-start path — the foils die from the pressure transient, not the vacuum.

At focused ion beam energies, sputter yields between 2 and 10 atoms per argon ion are typical.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 94

Tabletop: The keV-yield plateau means any small ion gun in the 5-25 keV range is a usable deposition tool; choose Ar for economy, Kr/Xe when a 2-3x rate matters more than gas cost.

the evaporation rates for these two metals differ by nine orders of magnitude, whereas their sputter yields differ by only a factor of two.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 100

Tabletop: When the target material is refractory (B, C, W, Ta) or reacts with every crucible, sputtering is the escape hatch; a graphite source holder adds only carbon, the lowest-yield contaminant.

Self-supported films usually display the same strength, toughness, and ductility as their bulk parent material.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 103

Tabletop: For a target that must survive beam, handling, and mounting stress, sputter-deposited beats evaporated at equal thickness; and pick the release agent for the process — salt layers for sputtering, organics only where nothing scrubs them.

At 1e-3 torr, the mean free path in the vacuum chamber is about 1 cm

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 103

Tabletop: If building a small sputter rig, separate the ion source (differentially pumped duoplasmatron-class gun) from a high-vacuum deposition region rather than lighting a glow discharge in the whole chamber — the film quality difference is structural, not cosmetic.

A typical deposition rate for substrates located 2.5 cm from the sputtering source is 20 ug/cm2/min. of titanium.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 114

Tabletop: Calibration point for sizing any home sputter-deposition scheme — mA and tens of keV, i.e. small-accelerator ion-source technology, not exotic hardware; a boron deposition run for a 100 ug/cm2 target is minutes, not days.

a uniformity of 10% over an area of cm2 with a recovery of at least 90% of the material.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 116

Tabletop: The zero-throw geometry turns the 1% efficiency of open evaporation into 90% — the method of choice when the feedstock (separated isotope, exotic compound) costs more than the labor of one-at-a-time targets.

The targets are sent to the users in containers filled also with dessicated argon.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 118

Tabletop: An argon-purged jar (or wide-mouth desiccator backfilled from a weld-gas cylinder) preserves oxidizable targets for months; assume any electroplated deposit is factor-of-2 nonuniform unless mapped.

however uniform an evaporation may be, the parting agent produces an inhomogeneous target.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 134

Tabletop: If a target will sit tilted to the beam or feed a spectrometer, the release-agent choice is a resolution decision, not a convenience; standard single-point thickness QA cannot see this defect — only straggling-width measurement can.

all targets should be produced with the use of Teepol as parting agent, or ... an organic parting agent with very little crystallite structure

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 143

Tabletop: Detergent-film release (Teepol-class) over salt release wherever the condensing metal tolerates it; and the alpha-straggling comparison is a complete bench-top target-quality metric using the same rig as the thickness measurement.

the foil can be blown off the frame almost instantaneously.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 206

Tabletop: Ground the target frame conductively, keep charged insulators (charged windows, PTFE hardware) away from foil positions, and make the foil-to-frame electrical contact generous — the mounting, not the film, is often what fails first under beam.

the most efficient energy transfer is achieved, when the electron beam and the molten droplet have the same diameter.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 232

Tabletop: Small-charge e-gun work is a spot-placement problem — half the beam power never enters a high-Z melt, so rated gun power overstates melt power by ~2x; don't size a gun (or a power budget) from evaporation enthalpy alone.

the beam spot will shift nearly 7 mm when the power supply is fully loaded and the beam will no longer hit the evaporant.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 228

Tabletop: Any home-built or surplus e-gun needs a stiff (regulated) HV supply before it needs more power; the copper-foil melt-hole trick is the free beam-alignment diagnostic.

sparks will occur, destroying the parting film and the thin isotope layer by hairline cracks.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 235

Tabletop: Grounding topology inside the evaporator is part of the recipe — the same charging physics that pits e-gun films will bite any deposition or beam system with floating fixtures near keV electrons.

the only way to avoid destruction of the targets is to cool the substrate or to periodically interupt the evaporation process

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 236

Tabletop: Substrate meltdown during deposition is the same radiation/conduction bookkeeping as beam heating (Corwin, this volume) with condensation enthalpy as the source term; refractory evaporants punish the substrate through radiation long before the film is thick.

The cleaning process is of utmost importance and each of the following steps contributes significantly to good results.

Thomas & Karasek (eds.), Proceedings of the Fourth Annual Conference of the Nuclear Target Development Society — ANL/PHY/MSD-76-1, Argonne National Laboratory (1975) — p. 257

Tabletop: Template for any compound that dissociates or splashes — pelletize the charge, chimney the boat, pre-warm the substrate with the source itself, and treat the color-temperature chart as the process instrument; valve off the diffusion pump so the compound vapor doesn't load the pump oil.

the powder was pressed between two stainless steel plates (Premier Brand Ferrotype) at about three tons per square inch (Minamisono & Ramsay, "Thick Targets for In-Beam Hyperfine Structure Study")

Fifth Annual Conference of the International Nuclear Target Development Society — LA-6850-C, Los Alamos Scientific Laboratory (1977) — p. 150

Tabletop: The thick-target recipe for activation and yield measurements where the beam must stop in the target — no evaporator needed, just a hydraulic press and polished plates.

the crossover point is about 210 C for nickel, 100 C for copper, and about 300 C for iron (Gursky, discussion "Prevention of Stress in Foils by Substrate Heating")

Fifth Annual Conference of the International Nuclear Target Development Society — LA-6850-C, Los Alamos Scientific Laboratory (1977) — p. 204

Tabletop: The missing variable when evaporated foils curl, buckle or shatter on float-off; set substrate temperature at deposition time — post-baking will not save a stressed film. Complements the ORNL-3021 evaporation recipes.

One can roll many useful foils down to the 1 to 5 mg/cm2 region with a small bench-type manually operated mill (Perry, discussion "Rolling of Metal Targets")

Fifth Annual Conference of the International Nuclear Target Development Society — LA-6850-C, Los Alamos Scientific Laboratory (1977) — p. 203

Tabletop: A jeweler's mill covers the whole thick-target range a small machine needs; the carbide-flat press is the fallback when rolling wastes scarce material on edge taper.

This can be avoided by making three to five passes at the same setting before going thinner (Perry, discussion "Rolling of Metal Targets")

Fifth Annual Conference of the International Nuclear Target Development Society — LA-6850-C, Los Alamos Scientific Laboratory (1977) — p. 204

Tabletop: The same-setting-passes trick (work-harden the surface before the next bite) and the electropolish-between-stages trick for oxidizing metals are the two non-obvious moves in amateur pack rolling.

The defects at the grain bounderies [sic] set an early limit during the rolling process (Kellner & Maier-Komor, "Rolling Thin Uranium Foils")

Proceedings of the Sixth Annual Conference of the International Nuclear Target Development Society — LBL-7950, Lawrence Berkeley Laboratory (1978) — p. 33

Tabletop: Explains why bought powder pressed into a pellet will not roll thin; the melt-and-decant-impurities step is what makes sub-mg/cm2 foils possible.

We noticed that material with a thickness of 0.5 mm or below gave the best results (Kellner & Maier-Komor, "Rolling Thin Uranium Foils")

Proceedings of the Sixth Annual Conference of the International Nuclear Target Development Society — LBL-7950, Lawrence Berkeley Laboratory (1978) — p. 35

Tabletop: The foil replicates every flaw of the jacket, not the rolls — jacket steel selection is the dominant quality variable in pack rolling.

reduced by about 3 to 10% per pass. When the jacket increased its size by approximately a factor of two the foil is placed in a new jacket (Kellner & Maier-Komor, "Rolling Thin Uranium Foils")

Proceedings of the Sixth Annual Conference of the International Nuclear Target Development Society — LBL-7950, Lawrence Berkeley Laboratory (1978) — p. 37

Tabletop: The complete quantitative schedule for rolling any metal to sub-mg/cm2; with it they reached 800 ug/cm2 uranium and 130 ug/cm2 molybdenum with no hot rolling.

at a temperature below 930 K, which was chosen to prevent phase transitions (Kellner & Maier-Komor, "Rolling Thin Uranium Foils")

Proceedings of the Sixth Annual Conference of the International Nuclear Target Development Society — LBL-7950, Lawrence Berkeley Laboratory (1978) — p. 38

Tabletop: Interpass and final annealing is what keeps a work-hardened foil rollable and flat; the phase-transition ceiling matters for any allotropic metal (Ti, Fe, U), not just uranium.

The Balsam remains tacky and retains foils indefinitely. It also has a low vapor pressure (Riel, "Gallium Rich Ga2O Targets for Use at Room Temperature")

Proceedings of the Sixth Annual Conference of the International Nuclear Target Development Society — LBL-7950, Lawrence Berkeley Laboratory (1978) — p. 105

Tabletop: A vacuum-compatible tacky mounting adhesive solves the foil-jumps-off-the-frame failure of float-mounting; pairs with the ORNL-3021 float-off recipes.

additional properties of low thermal conductivity and high electrical resistivity reveal it to be a poor choice for accelerator targets (Lozowski, "A Dry Powder Technique for the Preparation of Carbon Foils")

Proceedings of the Sixth Annual Conference of the International Nuclear Target Development Society — LBL-7950, Lawrence Berkeley Laboratory (1978) — p. 116

Tabletop: Beam-stopping carbon (and the thermal/electrical selection argument — a target material must conduct heat and charge away) from a drugstore powder blower and a hydraulic press; developed at a cyclotron facility for cyclotron targets.

The sputtering "leveled" the copper surface (Meens, "Vacuum Tight 208Pb Foils")

Proceedings of the Sixth Annual Conference of the International Nuclear Target Development Society — LBL-7950, Lawrence Berkeley Laboratory (1978) — p. 169

Tabletop: Pinholes replicate substrate defects, not evaporation errors; and one sacrificial natural-material run with a grid of weighed squares characterizes a boat geometry forever.

The wheel thus had to be rotated at a velocity of 666 rpm (equal to 20 deg in 5 ms or during one macropulse).

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 45

Tabletop: The design move — spread the duty cycle over many target areas, and if the beam is pulsed, lock the rotation phase so no single spot sees consecutive pulses — scales to a bench wheel behind any external beamline; the 1e17-particle survival figure sets the achievable scale.

Low melting-point elements like Pb or Bi are sandwiched between C layers for the use on target wheels, thus extending the stability and life-time

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 29

Tabletop: Direct recipe for any soft-metal target a small machine bombards; the carbon skins add mechanical strength, radiation cooling, and conduction paths for a few ug/cm^2 of added material.

An important problem is overheating of the substrate by a large, molten ball of material.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 208

Tabletop: Applies verbatim to boron and enriched-isotope work in a bench evaporator; the water-cooled pedestal trick (molten zone confined to the pellet top, pedestal only 3-5 cm across) is stated for induction-heated boron specifically.

If pitting or burn-up of the copper foil substrate occurs increase cooling. if curling occurs as the deposit thickens, increase heating

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 99

Tabletop: The pitting-vs-curling pair is a complete closed-loop tuning rule for any hot deposition onto a cooled backing — stress control by temperature, readable by eye. Also note the loose clamp so the foil can contract.

A large excess of Mg must be avoided to preclude formation of Mg2Si instead of Si.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 98

Tabletop: The whole metallothermic-reduction pattern (reductant choice, closed crucible, acid leach of the oxide by-product) is the standard route from affordable oxide feedstock to a solid target; directly relevant if boron or silicon targets are ever made from oxide.

slackening gives approximately an order of magnitude increase in the foil lifetime.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 16

Tabletop: Thermal-cycling stress, not sputtering, kills taut thin foils — the slack lets the foil move instead of tear. Any thin window, stripper, or degrader foil on a small machine should be mounted with deliberate slack (or spare stock budgeted; heavy-ion foil lifetimes ran minutes to hours).

is expected to be only the order of 1 hr.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 55

Tabletop: Proton beams are far gentler than 127-I, but the engineering lesson stands — anything thin in the beam needs replacement without opening the chamber. A multi-position foil/target ladder on a next machine's chamber costs little at design time and a vent-and-pump cycle every failure otherwise.

foils must be flat since ripples increase the effective source thickness and thereby degrade the performance.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 224

Tabletop: An existence proof that in-vacuum consumable-changers can share space with a live dee structure, and the cleanest statement in this collection that foil flatness is an orbit-quality parameter, not cosmetics — relevant to any internal-foil or internal-target scheme.

a cold filament which produces a temperature rise of the evaporant of only ~ 10 C

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 249

Tabletop: The commercial gun class (Ion Tech FAB11NS type) is bench-scale and vacuum-modest — the natural route to boron and refractory films for targetry without an e-gun; neutral-beam operation also suits insulating targets that would charge under ion-only sputtering.

the gun be at a thirty degree angle to the horizontal surface and about 5 cm from the sputter source.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 250

Tabletop: A complete recipe card for commissioning a sputter gun in a diffusion-pumped bell jar of exactly the archive's class; the see-the-beam-in-the-dark alignment trick costs nothing.

it can be left virtually unattended overnight and usually for several days with only slight adjustments.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 251

Tabletop: A 1 mg/cm^2 durable film is a multi-day sputter run — schedule accordingly or reserve sputtering for thin layers and adhesion coats; deposits are notably adherent, with a small implantation component.

only 2.3 mg of Zr were consumed in the preparation of 5 targets of 0.1 mg/cm2

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 38

Tabletop: Sets the material-efficiency benchmark for enriched or expensive feedstock (boron isotopes included) — milligrams in, multiple targets out, versus tens of milligrams lost in an evaporation plume.

with adequate care to ensure cleanliness, high quality RDM targets and stoppers can be produced reliably and easily

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 148

Tabletop: The general mounting lesson — flatness comes from a polished reference surface plus elastomer-mediated even tension, and cleanliness of foil and surface set the achievable quality. Capacitance-vs-distance is a nonmagnetic gap gauge usable anywhere two conducting planes must be set um-close.

Attempts at single step evaporations to these thicknesses were unsuccessful because of rupturing of the foil due to heat damage.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 230

Tabletop: Stretched polypropylene is the standard thin window for gas counters and low-energy vacuum isolation; the step-and-cool metallization discipline applies to coating any plastic film. Same material class as the detector windows the diagnostics literature assumes.

any remaining traces of moisture would result in failure to produce a self-supporting target

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 233

Tabletop: The two moisture checkpoints (bake substrate before the parting agent; methanol-displace water after float-off) are cheap insurance on every float-off evaporation — the same practice ORNL-3021's thin-film procedures assume but rarely state.

there is a "best ratio" r/h 0.7 which generates a minimum relative thickness variation far below 1% across the target.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 116

Tabletop: The uniformity-vs-economy trade in one number pair. GSI's rotating fixture (tilted 7 deg, 12 rpm) held +-1% on plate centers for stripper-foil carbon by the same principle — a small motorized turntable upgrades any bell-jar evaporator.

very small quantities of metals such as tungsten, tantalum, and molybdenum can be used in miniature systems

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 224

Tabletop: The one route in the volume to thick refractory-metal targets and coatings without an e-gun or rolling mill — though fluoride chemistry demands real gas-handling respect; note the parallel to CVD boron routes if boron targetry is ever pursued.

relatively high strengths and in some cases were virtually transparent.

International Nuclear Target Development Society Workshop — ANL/PHY-84-2, Argonne National Laboratory (1983) — p. 238

Tabletop: A genuinely low-tech thick-oxide route — solution chemistry plus an oven, no vacuum plant — suited to oxide targets (including B2O3-adjacent chemistry) where elemental form is not required; loading scales with solution concentration.

The dee biasing scheme was considered too awkward to apply, chiefly because the variable frequency requirement had already led to a rather complicated mechanical design.

Fulbright, The Sparker, a Device to Overcome the Multipactor Difficulty in Starting the Oscillator of a Cyclotron — NYO-9359, University of Rochester (1961) — p. 2

Tabletop: Transferable decision pattern: on a machine whose dee stem is grounded through the tank structure, retrofitting DC bias means rebuilding the stem insulation, while a shock starter touches nothing but a spare port. Choose the quench that is additive.

The spark gap is adjusted so that the sparking rate is roughly two per second. Ordinarily a single spark will cause oscillation to commence.

Fulbright, The Sparker, a Device to Overcome the Multipactor Difficulty in Starting the Oscillator of a Cyclotron — NYO-9359, University of Rochester (1961) — p. 3

Tabletop: Complete parts list (values on Fig.2, PDF p.8). A sub-joule impulse sufficed on a 27" machine; a smaller dee system needs proportionally less. The 30 kV supply is the only nontrivial part, and a NST or flyback-class supply covers it.

Because the loop is oriented at right angles to the axis of the cavity, the RF voltage induced in the loop is very small, even with full dee voltage.

Fulbright, The Sparker, a Device to Overcome the Multipactor Difficulty in Starting the Oscillator of a Cyclotron — NYO-9359, University of Rochester (1961) — p. 3

Tabletop: General principle for any diagnostic or starter coupling added to a resonator: choose an orientation that is null for the operating mode. The impulse still couples because the spark's broadband ring excites wall currents, not the clean mode — an inefficient coupler is acceptable precisely because the required kick is small.

partly because it was more convenient in our case since the dee chamber is rather crowded, and partly because we thought that the RF pickup problem would cause less trouble with inductive coupling.

Fulbright, The Sparker, a Device to Overcome the Multipactor Difficulty in Starting the Oscillator of a Cyclotron — NYO-9359, University of Rochester (1961) — p. 4

Tabletop: Directly usable trade note: a loop near the dee stem (outside the beam region) beats a capacitive plate facing the dee in a small chamber where every square inch by the dee is contested. Do not optimize the coupler — "works with margin" arrived at the first, deliberately inefficient geometry.

Two experimental models had values of 0.37 and 0.30, but in both cases it was necessary to use conductor sizes which were available but not specifically designed for the job.

Wakerling & Guthrie (eds.), Magnets and Magnetic Measuring Techniques — TID-5215, Radiation Laboratory, University of California (1949) — p. 22

Tabletop: Amateur coils are almost always wound from available magnet wire — budget the pessimistic 0.3-0.4 space factor, not the textbook 0.5, when sizing the coil window.

The forces tending to separate the halves are surprisingly large and if overlooked can be disastrous.

Wakerling & Guthrie (eds.), Magnets and Magnetic Measuring Techniques — TID-5215, Radiation Laboratory, University of California (1949) — p. 19

Tabletop: Directly relevant to removable pole caps and bolt-on shim plates on a small H-frame — the retention hardware must react a lateral load, not only the axial pull normally computed from B^2/2mu0.

As verified by practice, Eq. 68 holds true to at least 0.1 per cent accuracy when the diameter of the wire is small compared to the diameter of the cylinder.

Wakerling & Guthrie (eds.), Magnets and Magnetic Measuring Techniques — TID-5215, Radiation Laboratory, University of California (1949) — p. 62

Tabletop: A machined-spool primary standard plus a fluxgate-free comparison puts sub-0.5% absolute field capability in a home lab; it is the piece that turns a flip coil from a relative into an absolute instrument.

a steel faceplate was placed over the face of the core, as shown in Fig. 3.14, to spread out the flux evenly before it crossed the gap.

Wakerling & Guthrie (eds.), Magnets and Magnetic Measuring Techniques — TID-5215, Radiation Laboratory, University of California (1949) — p. 141

Tabletop: The reason laminated or relieved pole structures carry a continuous pole face; applies to any lightening-hole or bolt-pattern pole cap on a small magnet — a modest face sheet decouples interior steel economies from gap-field quality.

the forces calculated on the basis of the average over the entire region will be lower than the true force.

Wakerling & Guthrie (eds.), Magnets and Magnetic Measuring Techniques — TID-5215, Radiation Laboratory, University of California (1949) — p. 144

Tabletop: On a tabletop the same ledger is short but identical in kind — gap pull, atmospheric load on the chamber, unbalanced pull on any asymmetric iron — and the mean-of-squares point matters wherever the field is nonuniform over the loaded area (pole edges, shim steps).

the space between the tank and the cores must be great enough so that the maximum separation is never more than twice the minimum separation.

Wakerling & Guthrie (eds.), Magnets and Magnetic Measuring Techniques — TID-5215, Radiation Laboratory, University of California (1949) — p. 146

Tabletop: Governs any shim pack, pole-cap seat, or chamber-lid-under-pole arrangement: a deliberately larger uniform standoff can beat a smaller irregular one, because +/-50% of a big gap passes where +/-50% of a tiny gap is unmachinable.

We have had available for our use a complete set of the Berkeley plans which was kindly placed at our disposal by Professor E. O. Lawrence.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 6

Tabletop: The same strategy that built the reference machine from the Rutgers/Houghton lineage. For any new machine, start from the closest documented working design (this corpus) and spend novelty only where the precedent is silent.

the supporting structure for the coils failed, presumably under the magnetic forces. The coils became distorted and short circuits developed.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 19

Tabletop: DIRECT at any scale: coil-on-coil and coil-on-iron forces scale with NI and B and have crushed amateur windings. Brace windings as if they will be pushed, and remember the yoke-steel trick — outer return-path steel raises gap field without touching pole-gap geometry.

the results indicated a force greater than 35 tons for the cyclotron magnet. For comparison the force of atmospheric pressure is 24 tons.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 30

Tabletop: Any ferromagnetic chamber lid or pole-integrated cover on a tabletop machine sees magnetic clamping comparable to or exceeding vacuum load — check both cases (energized/de-energized) for deflection, and expect assembly/disassembly forces. Stray field at the RF tube/amplifier is likewise a real design input for a compact machine.

notably the bolts securing the one-inch thick sections of the cover plates, the screws holding the copper liners, and a gap where the shim is relieved to accomodate water lines

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 33

Tabletop: DIRECT — an H-frame yoke is item (1) by construction. Keep fasteners, liner screws, and cooling-line reliefs symmetric in the pole region, or place them where the survey says the beam doesn't care.

this correction was made the criterion for final adjustment rather than reference to mechanical measurements.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 41

Tabletop: DIRECT — thousandths of pole tilt are visible in a tabletop field survey and in beam behavior. Shim the measured field, not the dial indicator; calibrate shim sensitivity from the first iteration and extrapolate; and expect a floor because every local correction spreads.

Initial testing of the system disclosed two leaks in welds, both of which were in stainless to mild steel joints.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 53

Tabletop: DIRECT — stainless-to-mild transitions (and any dissimilar pair) crack and porosity-leak preferentially; put them where they can be reached for repair, or design them out with transition flanges and gaskets.

The skin is of electrolytic high conducitvity copper with 1/4, 3/8, and 5/8" copper tubes silver soldered on the back side for water cooling.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 58

Tabletop: The construction vocabulary (EHC copper skin, silver-soldered cooling, silver-plated RF joints, high-pressure sliding contacts) is exactly what a 5-13 kV LDMOS-driven dee upgrade needs; split-for-repair is cheap foresight at any scale. Same contact-pressure concern as the nyo-9683/ornl-2648 sliding-contact rules.

the filament may be replaced without breaking the vacuum of the tank proper.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 65

Tabletop: The reference machine's filament-change downtime is this exact problem, solved in 1951: a small gate-valved source lock plus an external sylphon/bellows positioner turns a half-day vent cycle into a minutes-long swap and adds live source alignment — high payoff on any filament-eating small machine. (The shuttered viewport is a free detail worth stealing.)

the plate is operated at d-c ground potential so that no insulation is required in the water lines.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 85

Tabletop: Solid-state amps moot the HV plumbing, but two transferable doctrines survive — pick the grounding scheme that keeps coolant out of the HV problem, and use source impedance (here transformer reactance) as passive inrush protection instead of active circuitry where a component's own rating allows it.