US3043986A - Particle accelerators - Google Patents

Particle accelerators Download PDF

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Publication number
US3043986A
US3043986A US645740A US64574057A US3043986A US 3043986 A US3043986 A US 3043986A US 645740 A US645740 A US 645740A US 64574057 A US64574057 A US 64574057A US 3043986 A US3043986 A US 3043986A
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Prior art keywords
high frequency
self
conductors
inductance
drift tube
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Expired - Lifetime
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US645740A
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English (en)
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Podliasky Ilia
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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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
    • H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
    • H05H7/14—Vacuum chambers
    • H05H7/18—Cavities; Resonators

Definitions

  • the present invention relates to particle accelerators of the type of proton synchrotrons, for the obtainment of very high energies (several billions of electron-volts or several tens of billions of electron-volts).
  • Such accelerators include accelerating tubes capable of creating a high frequency field which supplies one or several impulses to the particles as they are passing at a given point of a tore-shaped vacuum-chamber. Said impulses are produced by the electric field existing between the edges of said accelerating tubes.
  • I may indicate the arrangement called drift tube, diagrammatically shown on FIG. 1 of the appended drawing.
  • I On FIG. 1, I have shown, at 1 and 2, passages formed by suitably metallized portions of the vacuum chamber.
  • the particles which follow the longitudinal axis of said vacuum chamber (shown in dot-and-dash lines) are in Faraday cage, except when they pass through the gaps 3 and 4 existing between drift tube 5 and passages 1 and, 2.
  • a high frequency voltage, supplied by an electronic generator 6 of variable frequency, is applied between tube 5 and elements 1 and 2 by means of a connection 7 which passes through an insulating plug 8.
  • the whole of the device is enclosed in a metallic casing 9 which is electrically connected with elements 1 and 2 and is intended to avoid radiation and electro-magnetic inductions to the outside.
  • tors 13,-1.4 and 15 serve to separate thehigh frequency cur-rents from the polarization currents which vary gradually.
  • FIG. 2 shows the electrical lay-out corresponding to the arrangement-of FIG. 1.
  • L designates the variable self-inductance'of elements 10 and '11
  • C is Cit the capacitanceof the system including 1, 2, 9 on the one the target.
  • FIG. 1 The arrangement of FIG. 1 makes it necessary to pass the high frequency currents and the core polarization currents through the same windings 10 and 11.
  • the number of turns of these windings is necessarily small (in order to avoid the so-called coil effects at the high frequency, the production of uncontrollable stationary waves, 'etc.)
  • the polarization source 1-2 must, most often, supply ahigh intensity current (several thousands of amperes) under a low voltage. This is a source of constructional difiiculties, and generator 12 becomes difiicult to control for the production of variable currents.- .This generator often becomes more complicated and more expensive than the high frequency generator 6 itself.
  • the object of the present invention is to obviate the drawbacks.
  • the self-inductanc means which are to be varied in accordance with the'variations of frequency of the high frequency source, are inserted directly between the tubular electrode and the wall of the chamber;
  • said electrode subjected to the high frequency is provided with a double wall the external element of which is connected, through at least two hollow conductors surrounded by ferrite rings, with the wall of the chamber, a ferrite polarization winding being housed in the hollow space including said conductors and the inside of the double wall of the electrode.
  • the system constituted by said conductors, their ferrite rings and the polarization winding, constitutes the above mentioned self inductance means.
  • the system constituted by the acceleratingtube and the ferrite surrounded conductors, seen from the high frequency generator, is equivalent to a high resistance. Therefore the influence of the individual inductance of the intake conductor becomes negligible even at-high frequencies.
  • I l 2 Furthermore, the above indicated arrangement of the polarization winding is such that said winding is wholly protected against the electrical and magnetic inductions of thefield existing in the chamber. In other words, the mutual inductance'between the polarization'circuit and the high frequency circuit is zero.
  • the hollow conductors surrounded by theferrite rings may constitute the secondary of a high frequency transformer the primary of which is constituted by some turns of a winding extending around the ferrites and passing between them and the hollow conductors.
  • the primary turns carriedby the two ferrite assemblies may be connected in the series together and serve to excite the tubular electrode through a symmetrical high frequency amplifier, (push-pull amplifier).
  • FIG. 6 shows a second embodiment of 'my invention.
  • the. accelerating tube is a drift tube.
  • This drift tube 16 is insulated from two metallized tubular elements 17 and 18 of the vacuum chamber by means of insulating rings '19 and 20.
  • the joints between tubular parts 17, 19, 16, 20 and 18 are gas-tight so that a vacuum can be preserved inside said parts, whereas the pressure in chamber 21 is the atmospheric pressure. Said vacuum averages millimeters of mercury.
  • drift tube 1 6 has a double Wall the external and internal elements of which are designated by reference numerals 22 and 23 respectively. The particles to be accelerated pass through the space limited by the internal wall element 23.
  • Tube 16 carries two hollow conductors 24 and 25 extending between the ,external element 22 of said tube 16' and the wall of chamber 21. These hollow conductors 24 and 25 have a double function. @First they constitute self-inductances for. the high frequency circuit and secondly they serve to shield the polarization windings passing therein and a single wire ofwhich is shown at 26- for the sake of simplicity.
  • Conductors 24' and 25 are surrounded by ferrite rings 27 juxtaposed so as to cover-most of the height of said conductors.
  • the differential permeability of these ferrite rings is varied by magnetic polarization thereof by means of winding'26.
  • This source 12a may be at least partly controlled by a discriminator D responsive to the phase difference between'the high frequency current and the voltage supplied to chamber 21 by genator 6a.
  • a device of this kind is disclosed in the following document: The RF. System of the Bevatron by C. Norman Winningstad of June 4, 1954 (U.C.R.L. 2,593, Berkeley, California); This generator has one terminal connected to the end portionof said chamber, on the one I hand, and its other terminal connected to the'outerele ment 22 of chamber '16 through a conductor 28, on the other hand. 1
  • I may feed'to the polarization winding 26 a suitably filtered portion of the current flowing through the electromagnet of the synchrotron. This is particularly advantageous when this current is filtered by means of an electronic device and includes only very weak harmonics in the frequency band which can excite the vibrations of the ionic. beam passing along the axis of tube 16.
  • FIG. 4 shows the high frequency electric lay-out corresponding to the construction of FIG. 3.
  • L, l and "C correspond respectively to the variable self-inductance of conductors 24- and 25, the individual self-inductance of the intake conductor 28 and the capacity of the system constituted by tube 16 on the one hand and elements 17, 18 and 21 on the other hand.
  • this last mentioned current is made to vary so that, for every value of the high frequency, resonance is obtained by tuning between the whole of the sel-f-inductances and the capacity of the system including the drift tube. Under resonance conditions, the whole of the device between conductor 28 and chamber 21 acts as a high resistance. In this case, the
  • the mean line of the magnetic field in the ferrites which surround conductors 24 and 25 is much shorter than in the case of a conventional construction. This permits a great reduction of the ampere turns of polarization supplied through Winding26 and contributes in simplifying the means which constitute the polarization source.
  • the hollow conductors 24 and 25 may bev made to act as high frequency transformer secondaries, so as to increase the reactance of the tube seen from the high frequency source.
  • the ferrites are surrounded by some turns (not shown on FIG. 3), extending parallel to conductors'24 and 25, respectively onthe inside and the outside of the ferrite rings 27.
  • Connection 28 is then dispensed with and replaced by the ends of the primary windings. These primary windings may then be connected in series together and be fed through a symmetrical high frequency source with respect to the ground.
  • This source may for instance be output of a push-pull amplifier, which is particularly interesting for various reasons (elimination of even harmonics, high efiiciency).
  • the arrangement according to my invention may therefore be fedfrom a symmetrical amplifier.
  • the self-inductance means are constituted by stationary wave coaxial cables packed Wth ferrite rings.
  • the fern'te stacks are lined on hte outside with con-- ductor tube forming the external armature of the coaxial cables.
  • the length of these cables is such that a transverse. stationary wave takes birth therein and contributes
  • FIG. 6 The construction of FIG. 6 is little different from that of FIG. 3, but in this case the elements 29 and 30 have a height such that the electric length of the coaxial cables filled with ferrite rings is close to 90. cables, short-circuited at their end 34, cause the formation of a purely transverse stationary wave working close to quarter Wave conditions.
  • a coaxial cable with ferrites having a length of 62 cm. already constitutes a quarter wave line. As this line is provided at its end with a capacity (one half of that existing between the drift tube, the two portions of the vacuum tube. and the earth), the length of every coaxial cable must be lower than one quarter of a wavelength or an odd multiple thereof.
  • the characteristic impedance and the phase velocity in the coaxial cable may be adjusted by providing annular air spaces between the ferrite rings and the metallic tubes which form the armatures of the coaxial cable. It may be domonstrated that these annular spaces contribute in reducing the dielectric losses and magnetic losses due to (hysteresis carrying effect, Foucault currents). In oposition with this, they increase the phase velocity and make the cables less easy to saturate. This is due to the fact that the permeability of these air spaces does not depend upon polarization and their presence requires a supplement of polarizing ampere-turns.
  • the ferrite cables In the case of particularly high frequencies, it may be advantageous in some cases to give the ferrite cables a length higher than that of one quarter of a wavelength but still somewhat lower than an odd number quarters of a wavelength. These cables'are still short-circuited at their end opposed to that connected with the drift tube and thus have the properties of the self-inductance with respect to the drift tube.
  • the conductors are constituted by thin tubes 29 and 30. and they form the internal conductors of the coaxial cables.
  • the ferrites that surround them are shown at 33.
  • the inner conductors 29 and 30 and the outer conductors 35 and 36 are short-circuited at the end 34.
  • Short-circuiting ring 34 is provided with a hole for the passage of the wires 37 of the polarization winding. This winding is, from the high frequency point of view, at the ground potential.
  • the cables contain a stationary wave the length of which becomes independent of the frequency. If every cable works for instance 'as a line corresponding to one fifth of wavelength at the lowest frequency of the high frequency generator, it will keep working in this way for the whole spectrum of this generator and will maintain the properties of a self-inductance within a range of frequencies which may vary These.
  • the coaxial cables are (or only one of them is) provided with connections 38 and 39 passing bet-ween the ferrite rings 33 and extending to the conductors 29 and 30.
  • the input connection 49 can then be dispensed with and the high frequency generator is connected on the one hand to conductors 33 and 39 interconnected with each other, and on the other hand to the earth (wall 41).
  • dri-ft tube 42 is fed with high frequency through cables which act as transformers, thus permitting a better utilization of a given electronic generator.
  • I may make use of only one of the connections 38 and 39, the other coaxial cable, which is not provided with an intermediate current connection, then acting as a'shock coil.
  • a tubular drift tube a tubular drift tube, a-casing made of a conductive material surrounding said drift tube, out of contact therewith, two tubular elements made of a conductive material in coaxial line with said drift tube at either end thereof and insulated travel of particles that extends through said tubular elements and said drift tube being evacuated, variable selftherefrom, said tubular elements being in direct electric contact with said casing, the cylindrical space for the inductance means directly interposed between said drift tube and the wall of said casing, the whole of said drift tube, casing, tubular elements and variable self-inductance means forming an oscillatory circuit, a source of cyclically varying high frequency voltage,-means, distinct from said self-inductance means, for connecting one terminal of said source with said casing, means, distinct from said self inductance means, for connecting the other terminal of said source with said drift tube, and means responsive to the cyclical variation of frequency of said source for automatically varying the self-inductance of said self-inductance means to maintain resonance
  • a tubular drift tube having a double wall over at least a portion of its length, a casing made of a conductive material surrounding said drift tube, out of contact therewith, two tubular elements made of a conductive material in coaxial line with said drift tube at either end thereof and insulated therefrom, said tubular elements being in direct electric contact with said casing, the cylindrical space for the travel of particles that extends through said tubular elements and said drift tube being evacuated, twohollow conductors at a distance from each other directly interposed between said drift tube and the wall of said casing, juxtaposed ferrite rings surrounding said conductors, the whole of said drift tube, casing, tubular elements, hollow conductors and ferrite rings forming an oscillatory circuit, a source of cyclically varying high frequency voltage, coupled with said circuit, and means, including a winding extending inside said hollow conductors and between the two wall elements of the double wall of said drift tube in the portion thereof located between said hollow conductors, for varying
  • -A particle accelerator according to claim 2 further including around said hollow conductors, conductor tubes forming the external portions of coaxial cables shortcircuited with said hollow conductors at their end farther from the drift tube.
  • tubular-elements made of a conductive material in coaxial tube and the wall of said casing, the whole of said drift tube, casing, tubular elements and variable self-inductance means forming an oscillatory circuit, a source of cyclically .varying high frequency voltage, means for coupling the terminals of said source with said casing and said drift tube, respectively,acrcss said self-inductance means, the portion of said coupling means which has a substantial inductance being on the other side of said self-inductance means from 'said drift tube and said casing and means responsive to the cyclical variation of frequency of said source for automatically varying the self-inductance of said self-inductance means to maintain resonance in said circuit.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
US645740A 1956-03-16 1957-03-13 Particle accelerators Expired - Lifetime US3043986A (en)

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FR1077802X 1956-03-16

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US (1) US3043986A (fr)
BE (1) BE555731A (fr)
CH (1) CH350731A (fr)
DE (1) DE1077802B (fr)
FR (1) FR1145828A (fr)
GB (1) GB844530A (fr)
LU (1) LU34990A1 (fr)
NL (2) NL104090C (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5168241A (en) * 1989-03-20 1992-12-01 Hitachi, Ltd. Acceleration device for charged particles

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4667111C1 (en) * 1985-05-17 2001-04-10 Eaton Corp Cleveland Accelerator for ion implantation

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2200962A (en) * 1937-07-14 1940-05-14 Gen Electric Ultra short wave device
US2237878A (en) * 1939-02-02 1941-04-08 Rca Corp Electron discharge device
US2329778A (en) * 1941-10-30 1943-09-21 Rca Corp Electron discharge device
US2379673A (en) * 1941-05-09 1945-07-03 Marconi Wireless Telegraph Co Superregenerative radio receiver
US2408410A (en) * 1941-06-19 1946-10-01 Bell Telephone Labor Inc Frequency converter
US2444194A (en) * 1944-03-20 1948-06-29 Rca Corp Frequency stabilization system
US2462856A (en) * 1942-05-19 1949-03-01 Sperry Corp Transmitter and/or receiver circuits
US2463617A (en) * 1941-03-28 1949-03-08 Bell Telephone Labor Inc Ultra high frequency harmonic generator
US2547061A (en) * 1945-12-17 1951-04-03 Int Standard Electric Corp Multiple gap velocity modulation tube
US2860279A (en) * 1955-04-18 1958-11-11 Ross E Hester High current linear ion accelerator

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2200962A (en) * 1937-07-14 1940-05-14 Gen Electric Ultra short wave device
US2233166A (en) * 1937-07-14 1941-02-25 Gen Electric Means for transferring high frequency power
US2237878A (en) * 1939-02-02 1941-04-08 Rca Corp Electron discharge device
US2463617A (en) * 1941-03-28 1949-03-08 Bell Telephone Labor Inc Ultra high frequency harmonic generator
US2379673A (en) * 1941-05-09 1945-07-03 Marconi Wireless Telegraph Co Superregenerative radio receiver
US2408410A (en) * 1941-06-19 1946-10-01 Bell Telephone Labor Inc Frequency converter
US2329778A (en) * 1941-10-30 1943-09-21 Rca Corp Electron discharge device
US2462856A (en) * 1942-05-19 1949-03-01 Sperry Corp Transmitter and/or receiver circuits
US2444194A (en) * 1944-03-20 1948-06-29 Rca Corp Frequency stabilization system
US2547061A (en) * 1945-12-17 1951-04-03 Int Standard Electric Corp Multiple gap velocity modulation tube
US2860279A (en) * 1955-04-18 1958-11-11 Ross E Hester High current linear ion accelerator

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5168241A (en) * 1989-03-20 1992-12-01 Hitachi, Ltd. Acceleration device for charged particles

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NL104090C (fr)
GB844530A (en) 1960-08-10
CH350731A (fr) 1960-12-15
BE555731A (fr)
DE1077802B (de) 1960-03-17
FR1145828A (fr) 1957-10-30
LU34990A1 (fr)
NL215323A (fr)

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