US3757237A - Ron beam method and means for reducing the power density of an internal cyclot - Google Patents

Ron beam method and means for reducing the power density of an internal cyclot Download PDF

Info

Publication number
US3757237A
US3757237A US00223418A US3757237DA US3757237A US 3757237 A US3757237 A US 3757237A US 00223418 A US00223418 A US 00223418A US 3757237D A US3757237D A US 3757237DA US 3757237 A US3757237 A US 3757237A
Authority
US
United States
Prior art keywords
orbits
internal
cyclotron
radius
particles
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00223418A
Other languages
English (en)
Inventor
G Hendry
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cyclotron Corp
Original Assignee
Cyclotron Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cyclotron Corp filed Critical Cyclotron Corp
Application granted granted Critical
Publication of US3757237A publication Critical patent/US3757237A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • 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
    • H05H7/10—Arrangements for ejecting particles from orbits

Definitions

  • ABSTRACT A method and apparatus for reducing the power density of the internal beam in an isochronous cyclotron at its extraction radius or an internal target wherein the internal beam in its orbits near and at the extraction or target radius is spread axially by applying to it a timevarying electrostatic field tuned to the natural axial oscillation frequency of the beam in such orbits.
  • One object of this invention is to increase the amount of internal beam current that can be extracted from an isochronous cyclotron or be applied to an internal target without overheating the target or extraction system.
  • Another object of this invention is to provide a simple method and means for increasing the axial height of the internal beam in its orbits near and at the extraction or the internal target radius.
  • FIG. 1 is a partially schematic cross-sectional view of a typical isochronous cyclotron in its median plane;
  • FIG. 2 is a top view of the axial beam spreader of this invention
  • FIG. 3 is an elevational view of the axial beam spreader of FIG. 2;
  • FIG. 4 is a schematic diagram of one oscillator circult useful in applying radio frequency voltage to drive the beam spreader of FIGS. 2 and 3.
  • the external beam extractable from isochronous cyclotrons or the usable beam for internal target impingement generally is limited by high power density on the extraction system or on the internal target, respectively. Any attempt to increase beam current increases the power density on these elements until they are destroyed by heat generated from accelerated particles impinging upon them. Beam power densities in isochronous cyclotrons are particularly high because the strong vertical focusing forces in the fringe field of the machine reduce the vertical beam dimension at the usual extraction or target radius.
  • This invention offsets that natural vertical focusing by increasing the internal beam height in its orbits near and at the extraction or target radius by applying to the beam a vertical time-varying electrostatic field tuned to the natural oscillation frequency of the internal beam about the median plane.
  • the natural oscillation frequency of the internal beam about the median plane is a consequence of the self-focusing of the orbiting particles and is one-half the orbital frequency at a particular radius.
  • the vertical time-varying electrostatic field is tuned to that frequency and drives the natural oscillation to greater amplitude. The increase in amplitude spreads the axial or vertical dimension of the beam in the vicinity Of the extraction or target radius.
  • this invention relates to the electrostatic extraction method disclosed in the U. S. Pat. No. 3,582,700 entitled Cyclotron Beam Extraction System issued on June 1, 1971 to George 0. Hendry.
  • the present mthod can be used alone or in combination with the Improved Cyclotron Beam Extraction procedures disclosed in copending application Ser. No. 118,751 filed on Feb. 25, 1971 by George 0. Hendry and Dale K. Wells.
  • FIG. 1 illustrates the orientation of the axial beam spreader of this invention with reSpect to the other components of a typical small isochronous cyclotron at its median plane.
  • a main d-c electromagnet defines a magnetic guide field for the particles orbiting within the evacuated region of the cyclotron.
  • the main d-c magnet includes a lower yoke slab 2, a pair of interconnecting iron legs 3, and two cylindrical iron pole bases 4, the lower one of which is partially shown in FIG. 1.
  • Two sets of three shaped hill pieces 9 mount on the pole tip plates in corresponding locations to produce the azimuthally varying field necessary for isochronous operation.
  • a pair of dees provide a radio frequency accelerating field and an ion source supplies ions for acceleration as is more fully described in U. S. Pat. No. 3,582,700.
  • the schematically illustrated extraction system comprises electrostatic deflection means 30 as shown in U. S. Pat.
  • the machine may have an internal target at about the same radius for internal beam impingement as is well-known in this art.
  • the axial beam spreader 40 mounts as shown in FIG. 1 to embrace l5 20 turns or orbits of the internal beam near the extraction or the target radius as the case may be. Orbiting particles pass through its vertical electrostatic field prior to reaching the target or the illustrated Preseptum unit 32 and electrostatic deflection means 30 at the extraction radius.
  • Radio frequency generator 41 applies a time-varying potential to the beam spreader. Its frequency is tuned to the natural axial oscillation frequency of the orbiting particles in the 15 20 turns or orbits at and preceding the extraction or target radius.
  • the axial beam spreader 40 is simply a pair of conductive copper deflection plates 43, 44 embracing the internal beam, one on either side of the median plane of the cyclotron.
  • the deflection plates mount upon non-conductive mounting block 45, for example, adjustably fixed to lower pole tip plate 66 in the location shown in FIG. 1.
  • Separate copper cooling traces 46, 47 cool each of the deflection plates and are used as an electrical connection supplying rf voltage across the deflection plates.
  • Conductive shield 48 shields the deflection plates from the rf accelerating field of the adjacent dees.
  • a tuned-grid tuned-plate oscillator as illustrated in FIG. 4 applies a time-varying voltage across deflection plates 43, 44 at its output terminals 50, 51.
  • the circuit includes a type 304-TL triode 52 the filaments of which are supplied through transformer 53 from 117V. line voltage.
  • Coil 54 and variable capacitor 55 in the tuned-grid circuit connect the grid through grid capacitor 56 and grid resistor 57 to system ground, terminal 51.
  • the tuned-plate circuit includes coil 58 and variable capacitor 59 and capacitors 60 and 61.
  • the plate sup ply in the described circuit is 0.4 amperes at 2,500 volts supplied through choke coil 62 with by-pass capacitor 63 to system ground.
  • the axial beat spreader and method have been applied to the portion of the internal beam of a small isochronous cyclotron covering about one inch inside of an approximately fifteen inch extraction radius or some l5 turns.
  • the internal beam was observed to spread axially by a factor of two when 2,500 volts zero to peak at 12.5 MHz was applied across deflection plates 43, 44.
  • the power density at the extraction or target radius is substantially reduced by a factor of two. This enables a substantial increase in beam current and is particularly important for economical production of radioisotopes and fast neutrons.
  • a method for reducing the power density of the internal beam of an isochronous cyclotron in its orbits near and at an internal target or extraction radius comprising the steps of accelerating the beam of charged particles within the guiding magnetic field and evacuated region of the cyclotron through said orbits;
  • a method for extracting a portion of the internal beam of chaRged particles orbiting in a cyclotron within its guiding magnetic field and evacuated region comprising the steps of increasing the axial height of that portion of the internal beam of particles to be extracted near an extraction radius;
  • Apparatus for extracting a portion of the internal beam of charged particles orbiting in a cyclotron within its guiding magnetic field and evacuated region including means increasing the axial height of that portion of the internal beam to be extracted in its orbits near and at an extraction radius;
  • preseptum means segregating that portion of said orbiting particles to be extracted at an extraction radius near the fringe of said magnetic field in the absence of any electrostatic field
  • electrostatic deflection means receiving said segregated particles and defining at the extraction radius an electrostatic deflection field, the location of which increases in radius with respect to the center of the cyclotron, to deflect the segregated particles from orbit.
  • the means increasing the axial height of the beam comprises means applying a vertical time-varying electrostatic field to said orbits of the beam at the natural oscillation frequency of the beam in said orbits.
  • the means increasing the axial height of the beam comprises I a pair of conductive deflection plates embracing said orbits, one on each side of the median plane of the cyclotron;
  • oscillator means generating and supplying to said plates a radio-frequency voltage at the natural oscillation frequency of the beam in said orbits.
  • Apparatus for reducing the power density of the internal beam of an isochronous cyclotron in its orbits near and at an internal target or extraction radius including a pair of conductive deflection plates emracing said orbits, one on each side of the median plane of the cyclotron; and
  • oscillator means generating and supplying to said plates a radio-frequency voltage at the naJural oscillation frequency of the beam in said orbits.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
US00223418A 1972-02-04 1972-02-04 Ron beam method and means for reducing the power density of an internal cyclot Expired - Lifetime US3757237A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US22341872A 1972-02-04 1972-02-04

Publications (1)

Publication Number Publication Date
US3757237A true US3757237A (en) 1973-09-04

Family

ID=22836410

Family Applications (1)

Application Number Title Priority Date Filing Date
US00223418A Expired - Lifetime US3757237A (en) 1972-02-04 1972-02-04 Ron beam method and means for reducing the power density of an internal cyclot

Country Status (5)

Country Link
US (1) US3757237A (enrdf_load_stackoverflow)
FR (1) FR2170228B1 (enrdf_load_stackoverflow)
GB (1) GB1378624A (enrdf_load_stackoverflow)
IT (1) IT986954B (enrdf_load_stackoverflow)
SE (1) SE381550B (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5600213A (en) * 1990-07-20 1997-02-04 Hitachi, Ltd. Circular accelerator, method of injection of charged particles thereof, and apparatus for injection of charged particles thereof
CN114340134A (zh) * 2022-01-14 2022-04-12 新里程医疗技术(深圳)有限责任公司 一种医用分离扇形回旋加速器中的能量可调束流引出系统

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5600213A (en) * 1990-07-20 1997-02-04 Hitachi, Ltd. Circular accelerator, method of injection of charged particles thereof, and apparatus for injection of charged particles thereof
US5789875A (en) * 1990-07-20 1998-08-04 Hitachi, Ltd. Circular accelerator, method of injection of charged particle thereof, and apparatus for injection of charged particle thereof
CN114340134A (zh) * 2022-01-14 2022-04-12 新里程医疗技术(深圳)有限责任公司 一种医用分离扇形回旋加速器中的能量可调束流引出系统

Also Published As

Publication number Publication date
FR2170228A1 (enrdf_load_stackoverflow) 1973-09-14
GB1378624A (en) 1974-12-27
IT986954B (it) 1975-01-30
FR2170228B1 (enrdf_load_stackoverflow) 1976-05-14
SE381550B (sv) 1975-12-08

Similar Documents

Publication Publication Date Title
US5504341A (en) Producing RF electric fields suitable for accelerating atomic and molecular ions in an ion implantation system
CN117936344A (zh) 用于生成高能离子射束的设备及方法
GB2175741A (en) Accelerator for ion implantation
US2626351A (en) Beam extractor
US3883761A (en) Electrostatic extraction method and apparatus for cyclotrons
US3757237A (en) Ron beam method and means for reducing the power density of an internal cyclot
Reistad et al. Measurements of Electron Cooling and" Electron Heating" at CELSIUS
US20240098871A1 (en) Drift tube electrode arrangement having direct current optics
US2738420A (en) Injection into charged particle accelerators
WO2018096648A1 (ja) 加速器および粒子線照射装置
Seidel Injection and extraction in cyclotrons
Budker et al. Relativistic stabilized electron beam: II. Brief review of experimental work
US2922061A (en) Particle accelerator
Baan et al. The SIN Injector Cyclotron
US2829249A (en) Apparatus for accelerating charged particles
Calder et al. Vacuum conditions for proton storage rings
Cappi et al. Upgrading the CERN PS Booster to 1 GeV for improved antiproton production
JPH0757897A (ja) 高周波型荷電粒子加速装置
US3374378A (en) Acceleration of heavy particles
Thornton et al. CYCLOTRONS DESIGNED FOR PRECISION FAST-NEUTRON CROSS-SECTION MEASUREMENTS
Yonemura et al. Development of FFAG Accelerator at KEK
Hirao An overview of accelerator developments in Japan.
JP2022109715A (ja) 円形加速器、および、粒子線治療システム
Neufeld et al. Positron injector of the VEPP-4M collider
Hakamata et al. Ion beam acceleration by an RFQ with an LC resonance circuit