US3227957A - Cyclotron-type particle accelerator - Google Patents

Cyclotron-type particle accelerator Download PDF

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Publication number
US3227957A
US3227957A US215100A US21510062A US3227957A US 3227957 A US3227957 A US 3227957A US 215100 A US215100 A US 215100A US 21510062 A US21510062 A US 21510062A US 3227957 A US3227957 A US 3227957A
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Prior art keywords
frequency
particles
magnet means
path
phase
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US215100A
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English (en)
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Feldmann Hans-Helmut
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Licentia Patent Verwaltungs GmbH
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Licentia Patent Verwaltungs GmbH
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H13/00—Magnetic resonance accelerators; Cyclotrons

Definitions

  • CYCLQTRON-TYPE PARTICLE ACCELERATOR Filed Aug. 6, 1962 in venzor: Z WJQZM W United States Patent 3,227,957 CYCLOTRON-TYPE PARTICLE ACCELERATOR Hans-Helmut Feldmann, Berlin-Hermsdorf, Germany, assignor to Licentia Patent-Verwaltungs-G.m.b.H., Frankfurt am Main, Germany Filed Aug. 6, 1962, Ser. No. 215,100 Claims priority, application Germany, Aug. 10, 1961, L 39,754 3 Claims. 01. 328-234)
  • the present invention relates to a fixed-frequency cyclotron-type particle accelerator.
  • the orbital frequency of electrically charged particles is proportional to their charge-mass ratio and the magnetic induction, While the orbital frequency is independent of the particle velocity, the latter being proportional to the radius of the orbit. It is on these considerations that the Lawrence principle of the ion accelerating cyclotron is based.
  • the frequency of the high-frequency generator should match the orbital frequency of the ions in order that as much energy as possible is transferred to the ions every time they pass through an accelerating gap, which, in turn, will cause the ions to reach the final radius as quickly, i.e., with as few orbits, as possible. If the accelerating and orbital frequencies are not equal to each other, the cyclotron will lose phase stability, because every time an ion passes through the accelerating gap there will be an increased phase shift, as a result of which the acceleration per gap decreases until it finally may even become negative. In the case of fixed-frequency or so-called isochron cyclotrons, it is therefore of the utmost importance that the induction across the air gap and the frequency of the accelerating voltage be matched to each other.
  • an object of the present invention to overcome the above drawbacks, namely, to provide a cyclotron in which optimal acceleration at all of the accelerating gaps is obtained even though the ions will, due to low accelerating voltage, have to execute a large number of turns or orbits before attaining the final velocity, and even though the magnetic guide field is of relatively low accuracy.
  • the present invention involves a fixed-frequency cyclotron having a magnet for producing the magnetic guide field which confines the particles and thus defines their path of travel, and a highfrequency generator for accelerating the particles along the confined path.
  • the invention specifically resides in the fact that special additional magnetic fields, which may be referred to as vernier fields, are provided approximately along the paths of the particles, the configurations of which fields are automatically regulated as a function of the phase of the orbiting particles taken with respect to the phase of the accelerating voltage.
  • the instant invention thus comprises a fixed-frequency cyclotron-type particle accelerator having means for generating a magnetic guide field providing a path for the particles, a high-frequency generator for accelerating the particles along the path, a plurality of additional magnet means for generating additional magnetic fields at different places along the path, and a plurality of control systems associated with the plurality of additional magnet means, respectively, each control system being responsive to the phase difference between the orbital frequency of the particles at the place at which the respective additional magnet means is located and the frequency of the high-frequency generator for automatically controlling the respective additional magnet means to bring the orbital frequency of the particles into substantially in-phase relationship with the frequency of the high-frequency generator.
  • the additional magnet means each comprise magnetic exciter windings arranged along the path, and each of the control systems comprises a probe located at the place at which the winding with which the respective control system is connected is located, as well as a phase comparison circuit having two inputs, one of which is connected to the probe and the other of which is connected to the high-frequency generator, and an output connected to the respective winding.
  • a phase comparison circuit having two inputs, one of which is connected to the probe and the other of which is connected to the high-frequency generator, and an output connected to the respective winding.
  • the present invention further resides in a method of controlling a fixed-frequency cyclotron-type particle accelerator having means for generating a magnetic guide field providing a path for the particles and a high-frequency generator for accelerating the particles along the path.
  • the method comprises the steps of comparing the phase of the orbital frequency of the particles, at a place along the path, with frequency of high-frequency generator, and applying at such point a vernier magnetic field whose size is a function of the phase difference between the two frequencies for bringing the orbital frequency of the particles into substantially in-phase relationship with are shown.
  • the first control system has a probe S connected to one of the two inputs of a phase comparison circuit S1 whose other input is connected to the highfrequency generator represented schematically as HF.
  • phase comparison circuit S1 is connected to the input of an implifier V whose output is connected to a vernier winding W
  • the other two control systems have probes S S phase comparison circuits SJ S1 and amplifiers V V respectively, the various components parts of each system being connected to each other and to the respective vernier windings W W in the manner described in connection with the first system.
  • the three windings are suitably mounted on a pole shoe of a guide field magnet which is otherwise not shown.
  • the ion source of the cyclotron is indicated at 11, and the path of the particles is indicated by the arrow shown in dashed lines.
  • the windings W W W are fashioned, for instance, as single turn coils through which flow currents indicated by the arrows.
  • the crosses represent the direction of the magnetic fields produced by the windings.
  • the distance between the coils can be smaller; moreover, the present invention is not limited to specifically three windings since more can be used, as indicated by the winding W shown in dashed lines; indeed, the greater the number of windings, the more accurate will the fine adjustment or vernier effect of the windings be.
  • the windings have the actual configuration depicted in the drawing.
  • each winding can be composed of a plurality of suitably connected subwindings, i.e., individual windings which together make up the total winding for any one control system.
  • the three windings are depicted as being arranged at different selected radii of the pole shoe 10.
  • Each winding is fed from its respective amplifier which, in turn, is controlled by its respective phase comparison circuit.
  • the latter compares the phase of the accelerating voltage HF with the phase position of the orbiting ions on the respective portion of the spiral path. The latter will, of course, be obtained from the respective probe.
  • the frequency of the accelerating generator as well as the current for the main exciter coils of the guide magnet (not shown) are kept constant.
  • the ions cannot at once be accelerated to travel along the outermost or maximum radius orbit because the magnetic field produced by the main guide magnet is not sufliciently accurate, the reason being, as explained above, the lack of phase stability.
  • the phase comparison circuit S1 which compares this phase with that of the high-frequency accelerating voltage HF.
  • the amount of this phase difference is fed, via the amplifier V to the vernier winding W which acts as a booster in that it produces a supplemental magnetic field acting on the ions, thereby reducing the phase difference to a negligible value. It will be appreciated, therefore, that the winding W serves, in effect as an auxiliary accelerating ring.
  • the ions after having been subjected to the action of winding W will after a number of further orbits, come under the influence of the second control system, i.e., the probe S will now pick up the phase of the ions, the phase comparison circuit S1 will compare this phase with that of HF, and the winding W receiving its signal via amplifier V will produce the necessary vernier booster field, thereby once again bringing the ions into phase with the HF.
  • the ions will be subjected to the action of the third control system which functions in precisely the same manner.
  • the ions will be kept in phase with the HF, even though there are relatively large deviations from the magnetic field strength which the main guide magnet theoretically should produce. Consequently, a cyclotron equipped with the fine adjustment according to the present invention will maintain a very high degree of phase stability while operating with relatively low accelerating voltages. This, as explained above, is desirable because low accelerating voltages involve low current heat losses. Moreover, it will be appreciated that the complexity of a fine adjustment means of the above-described type is far less than that of a magnetic field which, in some other way, is made to maintain the desired accuracy. According to the instant invention all that is required is that the frequency of the accelerating generator be kept constant with a high degree of accuracy, which can readily be done, for instance, by
  • a fixed-frequency cyclotron-type particle accelerator comprising, in combination:
  • each control system being responsive to the phase difference between the orbital frequency of the particles at the place at which the respective additional magnet means is located and the frequency of said high-frequency generator for automatically controlling said respective additional magnet means to bring the orbital frequency of the particles into substantially in-phase relationship with the frequency of said high-frequency generator,
  • phase comparison circuit having (i) two inputs, one of which is connected to the probe and the other of which is connected to said high-frequency generator
  • each control system further comprises an amplifier interposed between the output of said phase comparison circuit and said respective additional magnet means.
  • a fixed-frequency cyclotron-type particle accelerator having a magnet for generating a guide field providing a path for the particles and a high-frequency generator for accelerating the particles along the path
  • the improvement which comprises: a plurality of Vernier magnets for generating Vernier fields at selected places along the path; and a plurality of control systems associated with said Vernier magnets, respectively, each control system including a circuit responsive to the phase difference between the orbital frequency of the particles at the place at which the respective vernier magnet is located and the frequency of the high-frequency generator for automatically controlling said vernier magnet to bring the orbital frequency of the particles into substantially in-phase relationship with the frequency of the high-frequency generator.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
US215100A 1961-08-10 1962-08-06 Cyclotron-type particle accelerator Expired - Lifetime US3227957A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEL39754A DE1146601B (de) 1961-08-10 1961-08-10 Festfrequenz-Zyklotron

Publications (1)

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US3227957A true US3227957A (en) 1966-01-04

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US215100A Expired - Lifetime US3227957A (en) 1961-08-10 1962-08-06 Cyclotron-type particle accelerator

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US (1) US3227957A (de)
CH (1) CH394424A (de)
DE (1) DE1146601B (de)
GB (1) GB1011395A (de)
NL (1) NL281694A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1125478A2 (de) * 1998-09-29 2001-08-22 Gems Pet Systems AB Vorrichtung zur rf-regulung
US20060164026A1 (en) * 2005-01-27 2006-07-27 Matsushita Electric Industrial Co., Ltd. Cyclotron with beam phase selector
EP2878180A4 (de) * 2012-07-27 2015-12-23 Massachusetts Inst Technology Strahlbahn eines synchrozyklotrons und rf-ansteuerung für ein synchrozyklotron

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1290269B (de) * 1965-03-10 1969-03-06 Akad Wissenschaften Ddr Verfahren zur reproduzierbaren Einstellung und Konstanthaltung der Kenngroessen des Ionenstrahls in einem Festfrequenz-Zyklotron

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2193602A (en) * 1938-05-06 1940-03-12 Westinghouse Electric & Mfg Co Device for accelerating electrons to very high velocities
US2898456A (en) * 1953-06-09 1959-08-04 Christofilos Nicholas Universal, constant frequency, particle accelerator
US2942106A (en) * 1955-11-21 1960-06-21 Willard H Bennett Charged particle accelerator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2193602A (en) * 1938-05-06 1940-03-12 Westinghouse Electric & Mfg Co Device for accelerating electrons to very high velocities
US2898456A (en) * 1953-06-09 1959-08-04 Christofilos Nicholas Universal, constant frequency, particle accelerator
US2942106A (en) * 1955-11-21 1960-06-21 Willard H Bennett Charged particle accelerator

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1125478A2 (de) * 1998-09-29 2001-08-22 Gems Pet Systems AB Vorrichtung zur rf-regulung
US20060164026A1 (en) * 2005-01-27 2006-07-27 Matsushita Electric Industrial Co., Ltd. Cyclotron with beam phase selector
US7315140B2 (en) * 2005-01-27 2008-01-01 Matsushita Electric Industrial Co., Ltd. Cyclotron with beam phase selector
EP2878180A4 (de) * 2012-07-27 2015-12-23 Massachusetts Inst Technology Strahlbahn eines synchrozyklotrons und rf-ansteuerung für ein synchrozyklotron
US9603235B2 (en) 2012-07-27 2017-03-21 Massachusetts Institute Of Technology Phase-lock loop synchronization between beam orbit and RF drive in synchrocyclotrons
US9615441B2 (en) 2012-07-27 2017-04-04 Massachusetts Institute Of Technology Phase-lock loop synchronization between beam orbit and RF drive in synchrocyclotrons

Also Published As

Publication number Publication date
CH394424A (de) 1965-06-30
GB1011395A (en) 1965-11-24
DE1146601B (de) 1963-04-04
NL281694A (de) 1964-12-28

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