Charged particle extraction apparatus and method of use thereof

• US 8,399,866 B2
• Filed: 08/03/2011
• Issued: 03/19/2013
• Est. Priority Date: 05/22/2008
• Status: Active Grant

• Current Assignee: Andrey Vladimirovich Balakin, Pavel Vladimirovich Balakin
• Original Assignee: Vladimir Balakin
• Inventors: Balakin, Vladimir
• Primary Examiner(s): MASKELL, MICHAEL P
• Application Number:
  US13/197,480
• Publication Number:
  US 20110284762A1
• Time in Patent Office: 594 Days
• Field of Search: 250/396.R, 250/492.1, 250/492.3, 313/26, 313/62, 315/503, 315/504
• US Class Current: 250/492.3
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 5/10 X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy A61N5/01 takes precedence
• CPC Class Codes: H05H 13/04 Synchrotrons
• CPC Class Codes: H05H 7/10 Arrangements for ejecting particles from orbits

Abstract

The invention comprises a charged particle beam extraction method and apparatus optionally used in conjunction with charged particle beam radiation therapy of cancerous tumors. The system uses a radio-frequency (RF) cavity system to induce oscillation of a charged particle stream. Sufficient amplitude modulation of the charged particle stream causes the charged particle stream to hit a material, such as a foil element of a set of foils. The foil decreases the energy of the charged particle stream, which decreases a radius of curvature of the charged particle stream in the synchrotron sufficiently to allow a physical separation of the reduced energy charged particle stream from the original charged particle stream where thickness of a selected foil is a function of energy of circulating charged particles. The physically separated charged particle stream is then removed from the system by use of an applied field and deflector.

Claims

1. An apparatus for extracting a circulating charged particle beam from a synchrotron, said synchrotron having a center, said apparatus comprising:

a set of n extraction foils, wherein n is a positive integer of at least two;

at least a one kilovolt direct current field applied across a pair of extraction blades; and

a deflector,

wherein the circulating charged particle beam passes through at least one of said n extraction foils resulting in a reduced energy charged particle beam,

wherein the reduced energy charged particle beam passes between said pair of extraction blades, and

wherein the direct current field redirects the reduced energy charged particle beam through said deflector,

wherein said deflector yields an extracted charged particle beam.

2. The apparatus of claim 1, wherein said set of n extraction foils comprises:

a first extraction foil;

a second extraction foil; and

a third extraction foil.

3. The apparatus of claim 2, wherein said first extraction foil comprises a first thickness, wherein said second extraction foil comprises a second thickness, wherein said third extraction foil comprises a third thickness, wherein said first thickness is less than said second thickness, wherein said second thickness is less than said third thickness.

4. The apparatus of claim 2, wherein said first foil comprises a thickness in the range of 30 to 70 micrometers, wherein said second foil comprises a thickness in the range of 60 to 140 micrometers, wherein said third foil comprises a thickness in the range of 150 to 250 micrometers.

5. The apparatus of claim 1, further comprising:

an actuator configured to alternately move a foil of said set of n extraction foils toward said center of said synchrotron and away from said center of said synchrotron.

6. The apparatus of claim 1, wherein a first extraction foil of said set of n extraction foils comprises a first density at least ten percent less than a second density of a second extraction foil of said set of n extraction foils.

7. The apparatus of claim 1, wherein at least one foil of said set of said set of n extraction foils comprises a chemical form of any of:

beryllium;

lithium hydride; and

carbon.

8. The apparatus of claim 1, wherein the circulating charged particle beam comprises a first radius of curvature greater than a second radius of curvature of the reduced energy charged particle beam passing through said extraction blades.

9. The apparatus of claim 1, further comprising:

an intensity controller controlling intensity of the extracted charged particle beam via a feedback control, wherein an induced current results from the circulating charged particle beam passing through at least one of said n extraction foils, wherein the induced current comprises a feedback input to said intensity controller.

10. A method for extracting a circulating charged particles from a synchrotron, comprising the steps of:

providing a set of n extraction foils, wherein n is a positive integer of at least two;

transmitting the circulating charged particles through at least one foil of said set of n extraction foils, said foil yielding reduced energy charged particles;

applying at least five hundred volts across a first pair of blades; and

passing the reduced energy charged particles between said first pair of blades,

wherein said first pair of blades redirect the reduced energy charged particles to a deflector, and

wherein said deflector yields extracted charged particles.

11. The method of claim 10, further comprising the step of:

using a first foil, of said set of n foils, in the extraction of charged particles comprising an energy less than 150 MeV; and

using a second foil, of said set of n foils, in the extraction of charged particles comprising an energy in excess of 150 MeV.

12. The method of claim 10, further comprising the steps of:

moving at least one foil of said set of n extraction foils toward said center of said synchrotron prior to said step of passing; and

moving said at least one foil away from said center of said synchrotron after said step of passing.

13. The method of claim 10, further comprising the step of:

selecting a member of said set of n extraction foils using knowledge of energy of said circulating charged particles.

14. The method of claim 10, further comprising the step of:

selecting a first foil of said set of n extraction foils for extraction of said circulating charged particles comprising a first energy; and

selecting a second foil of said set of n extraction foils for extraction of said circulating charged particles comprising a second energy, said second energy at least one hundred twenty percent of said first energy.

15. The method of claim 10, further comprising the step of:

controlling intensity of the extracted charged particles beam with an intensity controller using a feedback control, wherein an induced current results from the circulating charged particles passing through at least one of said set of n extraction foils, wherein the induced current comprises a feedback input to said step of controlling intensity.

16. A method for repetitively extracting circulating charged particles from a synchrotron, comprising the steps of:

providing said synchrotron;

providing a set of at least two extraction foils;

selecting a member of said set based on energy of the circulating charged particles;

using an actuator to move said selected member of said set of extraction foils toward a center of said synchrotron;

transmitting the circulating charged particles through said selected member to yield a reduced energy charged particle beam;

moving, with said actuator, said selected member of said set of extraction foils away from the center of said synchrotron; and

repeating said steps of;

selecting, using, transmitting, and moving.

17. The method of claim 16, wherein at least one of said extraction foils consists essentially of atoms comprising six or fewer protons.

18. A method for extracting circulating charged particles from a synchrotron, comprising the steps of:

providing said synchrotron;

providing a set of at least two extraction foils;

selecting a member of said set of extraction foils based on energy of the circulating charged particles;

transmitting the circulating charged particles through said selected member to yield a reduced energy charged particle beam; and

redirecting said reduced energy charged particle beam out of said synchrotron using a Lamberson magnet.

19. The method of claim 18, wherein a second extraction foil of said at least two extraction foils comprises a second thickness at least double a first thickness of a first extraction foil of said at least two extraction foils.

20. The method of claim 18, further comprising the steps of:

inducing a change in a radius of curvature movement of the circulating charged particles;

(1) after acceleration of the charged particle beam to a selected energy and (2) prior to said step of transmitting the circulating charged particle beam through said selected member; and

controlling intensity of said extracted charged particles using an electron flow resultant from the circulating charged particles transmitting through said selected member.