Cyclotron general design rules

Size: 10-inch pole diameter ... Dee voltage: 10,000 to 14,000 volts dee-to-dee; R.F. power: 2,000 watts; R.F. frequency: 25.68 megacycles ... Magnetic field strength: 17,000 gauss

McGuire, The Iowa State University 1.5 MeV Undergraduate Cyclotron (1961) — p. 9

Tabletop: This is the closest historical analogue to a next machine's target: same pole diameter as the reference machine, ~3x their field and ~10x their dee voltage buy ~10x the energy.

With the chamber in place, the separation between the pole tips is 3.81 cm, giving a maximum magnetic field of 1.28 T at 70 A ... requiring 18 C water flowing at 0.8 gallons per minute (at 50A)

Yuly, The Houghton College Cyclotron: a Tool for Educating Undergraduates — Cyclotrons 2013, WE1PB01 (2013) — p. 2-3

Tabletop: A purchasable-magnet benchmark almost exactly at the reference machine's scale; the 0.8 gpm figure sizes a chiller for a ~kW-class coil.

The highest proton energy obtained so far is about 160 keV, with a 3 pA peak near the correct magnetic field of 796 mT for 12.1 MHz.

Yuly, The Houghton College Cyclotron: a Tool for Educating Undergraduates — Cyclotrons 2013, WE1PB01 (2013) — p. 5

Tabletop: Calibrates expectations exactly at the reference machine's operating point (~160 keV) and names the three things that gate the next factor of 2-3: magnet current, cooling, RF frequency.

Ion Source Power [kW] 1.5 (Table 1)

Lee et al., Investigation of Minimized Consumption Power about 10 MeV Cyclotron — Cyclotrons 2016 (2016) — p. 2-3

Tabletop: Sets the ceiling-class datum; the reference machine's design point (~0.1-0.2 kW) is a deliberate 10x derating of commercial practice, consistent with uA-class rather than 100-uA-class internal beam.

Once the three dees are isolated electrically by adjusting the neutralizing loops the machine behaves like three separate single-phase systems.

Smith, A Three-Phase Radiofrequency System for Cloverleaf Cyclotrons — UCRL-3153 (1955) — p. 18

Tabletop: The architectural moral - decouple first, then control each loop as SISO - applies to any interacting set of tabletop loops (tuner vs coupling vs amplitude on a next machine); trying to servo a coupled system is how the programme burned months (ucrl-3187 p.5-6,11).

The possibility of changing the electrical frequency and gradient to match operating conditions eliminates difficulties arising in magnetic extraction systems for variable-energy machines.

Stubbins, Radiofrequency System for Extracting Particles from a Cyclotron — UCRL-8578 (1958) — p. 4

Tabletop: Directly supports the next machine's plan-of-record (electrostatic deflector, no fixed magnetic channel) - an educational machine that will run at more than one field/energy point wants its extraction strength on a knob, not in iron.

The bombardments are tabulated below: Beam profile 10, Isotope production 8, Experimental 16, Energy 5, Physics 7, Radiation damage 4.

Howard (ed.), Electromagnetic Research Division Quarterly, period ending 31 March 1952 — ORNL-1339 (1952) — p. 8

Tabletop: A quarterly cadence in miniature for the reference machine — after any change (RF upgrade, source rebuild), the run log should show dedicated profile and energy runs before "physics" runs; ORNL treated characterization as scheduled work, not overhead.

We have not attempted to obtain particle beams for the cases discussed here as we do not plan to accelerate protons until the shielding vault is completed.

Jungerman, Kibbe & Peek, Central Region Studies for Incorporating an Axial Ion Source in the Davis 76-in. Cyclotron — UCD-CNL-49 (1966) — p. 7

Tabletop: Directly relevant to the plan's open shielding gate: species choice is a radiological control. Commissioning a new machine (or the reference machine's RF upgrade) on H2+ at the same B*rho halves the per-nucleon energy and keeps early tuning below neutron thresholds — the machine physics transfers to protons afterwards, exactly as Davis planned.

It appears that the unit costs can only be determined after the cyclotron has been in operation for several years, so estimates must be employed.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 30

Tabletop: A 1952 statement of the plan's own doctrine - cost models are gated on real operating data, so freeze the estimate, build, and revise with actuals rather than polishing the spreadsheet.

This field strength depends on the design and the size of the magnet and cannot be determined without a model magnet.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 33-38

Tabletop: The steel-vs-power tradeoff behind "how hard to push B" - for a fixed 757-lb-class magnet the answer comes off the real excitation curve, not theory; FEMM plays the role of the model magnet for first passes.

the term "resistance" is used there to indicate the reciprocal of the conductance. The use of resistance presents perhaps a clearer picture through the use of an electrical analog.

Foss et al., Cyclotron Component Design Technical Reports — TID-454 (1952) — p. 132

Tabletop: The report's method in one sentence - their 32-in pumps' 13,700 l/s collapsed to 8,300 l/s effective inside the dee (air). Amateur systems routinely lose the same 40-60% to geometry; budget from the source outward, not the pump inward.

Measurements of the internal beam of the ORNL 86-inch cyclotron very early indicated that the energy of the proton beam might vary as much as +/-10% from H-rho calculations.

Cohen, Measurement of Beam Energy and Energy Distribution on an Internal Cyclotron Target — ORNL-1347 (1952) — p. 5

Tabletop: Verified on the page image, and the direct historical support for this collection's energy-convention discipline: the reference machine's "150 keV-class computed" is a convention, not a measurement. For a next machine's B11(p,alpha) work, where yield vs energy is steep, measure energy AT the target (absorber stack in front of the PIPS, or foil methods) every time tuning changes.

the cyclotron operating conditions are so different from those used in normal operation that it may well be that the energy distribution is not the same.

Cohen, Measurement of Beam Energy and Energy Distribution on an Internal Cyclotron Target — ORNL-1347 (1952) — p. 9

Tabletop: Directly relevant methodological honesty for a next machine, where detector protection will likewise force attenuated or detuned beams for some measurements. Log the machine state (dee voltage, field, frequency, source position) alongside every energy measurement so diagnostic-mode and run-mode data are never silently mixed.

The beam energy is really a three way compromise between cost, the advantages of higher energy, and the ability to extract a large fraction of the beam.

Oak Ridge National Laboratory, A Proposal for the Mc² Isochronous Cyclotron — ORNL-3540 (1963) — p. 20

Tabletop: Directly transferable process rule (their answer, 810 MeV / 100 uA, is not): write down the compromise axes for a next machine's energy point instead of inheriting a number.

conceived as an experimental device to examine the practicability of isochronous acceleration ... to reveal any unexpected phenomena ... and finally, to demonstrate the feasibility of a high efficiency beam extraction system.

Oak Ridge National Laboratory, A Proposal for the Mc² Isochronous Cyclotron — ORNL-3540 (1963) — p. 263

Tabletop: The electron-analogue idea (keV electrons stand in for MeV protons at equal T/mc2) is itself 810-MeV-motivated, but the three-purpose charter for any risk-retiring model or prototype is scale-free.

All suffer from one or more of the following defects: excessive space requirements, lack of terminal space, lack of terminal auxiliary power, and lack of flexibility for future uses.

Oak Ridge National Laboratory, A Proposal for the Mc² Isochronous Cyclotron — ORNL-3540 (1963) — p. 149

Tabletop: Their injector shoot-out (tandem vs open-terminal vs pressurized vs Van de Graaff) models the documentation style for any subsystem selection in mark2_design_notes open decisions.

the average contingency for the project is approximately 20%, but it varies on specific items from 15% to 40%, depending on the accuracy with which the estimate could be made.

Oak Ridge National Laboratory, A Proposal for the Mc² Isochronous Cyclotron — ORNL-3540 (1963) — p. 234

Tabletop: 1963 AEC percentages, but the structure transfers whole to any bill-of-materials estimate: contingency is not one number — catalog items get little, anything not yet fully designed (their rf cavity: 30%) gets a lot.

Provisions have been made in all plans to make the addition of the medical facility as simple and as economical as possible ... The cost of the medical facility is not included in the initial cost of the project

Oak Ridge National Laboratory, A Proposal for the Mc² Isochronous Cyclotron — ORNL-3540 (1963) — p. 22

Tabletop: Scale-free scoping discipline for the business plan: design the educational-machine baseline with hooks for upgrades (extraction port, shielding growth, second station) without loading their cost onto gate-one.

Because the major novelties and complexities of the project lie in the area of the machine and the beam handling, these areas were programmed. The building and shielding portions of the project were not programmed

Oak Ridge National Laboratory, A Proposal for the Mc² Isochronous Cyclotron — ORNL-3540 (1963) — p. 252

Tabletop: Scale-free effort allocation: plan the risky subsystems (source, RF, field mapping) at fine grain; the workshop-and-bench logistics need no Gantt chart.

All activities on the critical path were then re-evaluated ... It was decided that the cyclotron vault and cyclotron building could be completed first, to allow the magnet assembly to begin at an earlier date.

Oak Ridge National Laboratory, A Proposal for the Mc² Isochronous Cyclotron — ORNL-3540 (1963) — p. 258

Tabletop: Scale-free (their iteration cut 8yr10mo to 6yr9mo); note also what sat on their critical path: magnet iron, field plotting, and 'shim if necessary' — field mapping is schedule, not an afterthought, at any scale.

Inasmuch as the equivalent diameter of the pole pieces is 44 in., the machine is more appropriately identified as the 44-in. cyclotron.

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

Tabletop: The reference machine's H-frame magnet is the analogous asset: energy upgrades (gap, shims, dees, rf power) can be staged around the same 757-lb iron for years, exactly as ORNL staged 1.5 -> 5 MeV -> (proposed) 48-in. heavy ions around one magnet line. Rename footnote: PDF p. 17.

such a cyclotron is feasible, that an energy definition of less than +/-10 kev could be achieved, and that deflected beams would be in the range of 1 to 10 ua

Howard (ed.), Electromagnetic Research Division Semiannual, period ending 20 March 1953 — ORNL-1531 (1953) — p. 19

Tabletop: Direct prior art for the plan's educational variable-energy accelerator concept - vary energy with field/frequency plus a movable target (cf. the 44-inch spacer), and buy energy DEFINITION with a simple analyzed beamline rather than machine perfection.

a choice of radius, 11 in. or 20 in., is thus obtained by shifting the position of the dees and target. In either case the ion source position remains unchanged and the beam orbits remain centered

Howard (ed.), Electronuclear Research Division Semiannual, period ending 20 September 1953 — ORNL-1663 (1954) — p. 18

Tabletop: Variable energy WITHOUT retuning B or rf - since E ~ r^2 at fixed field/frequency, a repositionable target (or dee assembly) gives an educational machine two calibrated energies for the price of one; the invariants to protect are source position and magnetic centering, exactly as ORNL did.

Beam radius, in. 11 / 20; Proton energy, Mev 1.5 / 4.9; Magnetic field, oersteds 6400; Magnet gap, in. 13.5; Maximum dee-to-dee potential, kv 100; Frequency, megacycles/sec 9.7 (spec table, condensed)

Howard (ed.), Electronuclear Research Division Semiannual, period ending 20 September 1953 — ORNL-1663 (1954) — p. 18

Tabletop: The nearest professional sibling to a next machine in this collection - same ~0.64 T field class and ~9.7 MHz as the reference machine's 0.59 T / 9 MHz, scaled up in radius and voltage. Use it to sanity-check B-f consistency and to see what 100 kV (vs the reference machine's ~0.8 kV) buys in radius terms.

This spacer moves the dees back from the center of the magnetic field so that the machine can be operated at approximately 1.5 Mev for test operation at very high proton currents.

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

Tabletop: Mirrors a staged-gate development logic - plan a low-energy high-current commissioning configuration as a designed-in mechanical state, not an improvisation, so beam physics problems are separated from full-energy hazards.

All other components of the present 44-in. cyclotron, oscillator, dee system, vacuum system, ion source, target-probe, and power supplies, would be utilized.

Howard (ed.), Electronuclear Research Division Semiannual, period ending 20 September 1954 — ORNL-1795 (1954) — p. 23

Tabletop: The strongest argument in this collection for clean interfaces between a next machine's subsystems (and for interface-control discipline generally) - ORNL could contemplate a heavy-ion machine for the price of iron and a tank because everything else unbolted.

a large amount of existing equipment was adapted for use in the accelerator, and many design compromises were accepted. Consequently, this machine lacks the versatility and reliability which are essential

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

Tabletop: The counterweight to thrift - surplus-equipment compromises in shielding provisions, magnet gap, and insulator ratings are the ones a finished machine cannot shed. When designing a next machine around salvaged parts, check each against this five-item list; anything on it deserves new hardware.

The major components have been assembled and vacuum-tested (see Fig. 5).

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

Tabletop: Schedule realism for the next machine's campaign - a professional division with machine shops took four reporting periods from revision concept to vacuum test, and the long poles were exactly the ones a next machine faces (outsourced fabrication, field shimming, ion source). Halving subsystem count does not halve this arc.

Performance of the model is considered sufficiently satisfactory to proceed with the full scale design and construction based on the model dimensions.

Anderson, Half-Scale Model Tests on the Three Quarter Wave R.F. System — UCRL-31 (1947) — p. 16

Tabletop: A next machine's dee/stem/tank is already benchtop-sized, so the transferable form is the mockup itself — a cheap RF-only copy (no vacuum) of the dee-liner geometry, swept with a VNA before the vacuum parts are machined. Same lineage as UCRL-64 and MDDC-1045 already in this collection.

Total Operating Time 831.3 ... 60.1 ... Outage Total 551.2 ... 39.9 ... Scheduled Operating Time 1382.5

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 33

Tabletop: A run log that records why each session ended, in fixed categories, turns anecdote into a failure Pareto within a year; expecting 40% downtime even with full-time staff calibrates what a spare-time machine can achieve.

Vacuum 128.6 ... 9.3 ... R. F. 22.1 ... 1.6 ... Power Supply 140.4 ... 10.2

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 33

Tabletop: Matches the failure record of small machines - the exotic subsystems (RF, source) are not the availability drivers; unglamorous supply and pump maintenance is where uptime is bought.

Beam Tuning 55.0 ... 4.0 ... Start Up and Shutdown 77.5 ... 5.6

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 33

Tabletop: Pump-down, filament conditioning, and field settling are a fixed tax per session; batching experiments into fewer, longer sessions raises beam-on fraction more than any hardware upgrade of similar effort.

In most cases development is in parallel with operation of the cyclotron. However, major changes may require shut-down of the cyclotron for these modifications to be effected.

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 19

Tabletop: Grouping every open-the-chamber job (seal replacement, source work, new feedthroughs) into one planned vent-and-rebuild window costs one pump-down and one reconditioning instead of many.

This may happen before the operator can determine the sensor causing the fault condition. Therefore, a device was needed which could detect and store the location of a large number of possible faults.

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 22

Tabletop: Any interlock chain needs first-fault capture - even a latching relay or logged timestamp per sensor - or intermittent faults (thermal, flow, vacuum burps) become undiagnosable ghosts that waste whole sessions.

One is assigned as priority faults, errors which must be corrected to continue cyclotron operation ... The other is non-priority faults, such as the failure of a mechanical vacuum pump which may be bypassed and operation continued.

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 22

Tabletop: Hard-wire the safety-critical chain (radiation, HV enclosure, cooling on powered magnets) so it cannot be acknowledged away, and give everything else a bypassable alarm; a system where every fault stops the machine trains its operator to defeat interlocks.

the R. F. dee voltage was lowered to approximately 50% of its normal value which is less than the threshold voltage.

Cyclotron Staff, Report of Cyclotron Operation 1 July – 31 December 1969 — NRL Memorandum Report 2103, Naval Research Laboratory (1970) — p. 23

Tabletop: There is a dee-voltage threshold below which no ions survive to full radius; gating against it - by stepping the regulator reference, not by unkeying the RF - pulses beam for detector duty-cycle or background measurements without any retuning transient.

the cyclotron was in operation 1680 hours, or about 18 hours per day.

Harvard University Cyclotron Laboratory, Quarterly Progress Report, 1 June – 31 August 1964 — p. 1

Tabletop: An upper anchor for what cyclotron reliability can reach once a machine is mature and continuously staffed - useful for calibrating expectations against the NRL 60% figure from a machine mid-upgrade.

Three days were lost due to failure of the refrigerator for the cold-trap above the diffusion pumps.

Harvard University Cyclotron Laboratory, Quarterly Progress Report, 1 June – 31 August 1964 — p. 1

Tabletop: Chillers, trap refrigeration, and compressed-air auxiliaries deserve the same spares-and-monitoring attention as the pumps they serve; when a trap warms, the machine is down just as surely as if the diffusion pump died.

A scheduled shutdown of about one week was required to install apparatus for pulsed deflection of the internal beam.

Harvard University Cyclotron Laboratory, Quarterly Progress Report, 1 June – 31 August 1964 — p. 1

Tabletop: Same pattern as NRL's engineering shutdown at a smaller scale - one planned vent, one reconditioning, all invasive work inside it; unscheduled opportunistic upgrades multiply pump-downs and conditioning time.

it is desirable to keep the driving coils as close to the air gaps as possible in order to reduce spreading and bowing of the field and to keep the largest possible fraction of the gap area usable.

Wakerling & Guthrie (eds.), Magnets and Magnetic Measuring Techniques — TID-5215, Radiation Laboratory, University of California (1949) — p. 25

Tabletop: Coils-near-gap is the reason cyclotron coils hug the poles rather than the yoke; the usable-fraction-of-pole-area argument is exactly the good-field-radius economics of a small machine.

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.

A magnet of this size when used with detuerons, is about the optimum dimensions in which deuterons may be accelerated profitably without resorting to frequency modulation.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 5

Tabletop: Any tabletop proton/deuteron machine sits far inside the fixed- frequency regime — phase slip there is set by field shaping and dee voltage, not relativity, so FM hardware is never the fix for small-machine beam loss.

it should be completely interlocked in such a manner that serious damage cannot occur due to any failure of the operator or of equipment such as water failure or a vacuum leak.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 95

Tabletop: DIRECT blueprint for a tabletop control panel or PLC: interlock- chain-ordered start, ready-light-with-reason indication (the diagnostic half most amateur panels omit), RF-enable as the terminal permissive, and a cooling run-on timer. Complements the ad-755510 interlock rules with the wiring-bookkeeping practice that keeps the system maintainable. Details pp.99, 107.

Total expenditures to date from all sources, excluding University of Washington overhead and staff salaries, has been $642,000.

The University of Washington 60-Inch Cyclotron: Progress and Status Report of Design and Construction — AECU-1951, University of Washington (c. 1950) — p. 124

Tabletop: Same cost anatomy the plan's budgeting already assumes: facility and infrastructure rival the machine, and the labor line is invisible because it is donated — the honest comparison for an educational-accelerator business is materials PLUS the labor a customer cannot donate. Corroborates the ornl-3540 cost-structure rules from the construction side.

(b) the multipactoring problem, common in the field of particle accelerators, rarely occurs in other industrial applications

Smith, The RCA 6949 as a Self-Excited Cyclotron Oscillator — UCRL-9435, Lawrence Radiation Laboratory (1960) — p. 7

Tabletop: The checklist for adapting ANY industrial/ham RF gear (including an LDMOS pallet) to a cyclotron: add spark protection, add a multipactor start plan, and only then worry about power. Fixed-frequency tabletop machines are spared only (c).

In this type of system the resonator is the frequency-determining element of the system; hence it is called a self-excited oscillator.

Smith, The RCA 6949 as a Self-Excited Cyclotron Oscillator — UCRL-9435, Lawrence Radiation Laboratory (1960) — p. 4

Tabletop: The live architecture decision for a next machine. An LDMOS chain driven by a synthesizer is a MOPA — it inherits ornl-2403's virtues (frequency authority, instrumentation) AND the self-excited literature's start-up disease (nyo-9359): the synthesizer holds frequency while multipactor holds the dee at zero. Smith's phase-discipline logic (feedback phase correct across the whole operating range) is the checklist item either way. High-SWR argument p.6.