CONTROLLED TRANSPORT SYSTEM FOR AN ELLIPTIC CHARGED-PARTICLE BEAM

• US 20110121194A1
• Filed: 10/16/2007
• Published: 05/26/2011
• Est. Priority Date: 10/16/2006
• Status: Abandoned Application

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Zhou, Jing, Chen, Chiping, Bhatt, Ronak J.
• Application Number:
  US11/873,075
• Publication Number:
  US 20110121194A1
• Time in Patent Office: Days
• US Class Current: 250/396.ML
• CPC Class Codes: H01J 23/02 Electrodes; Magnetic control means; Screens associated with resonator or delay system H01J23/16
• CPC Class Codes: H01J 23/08 Focusing arrangements, e.g. for concentrating stream of electrons, for preventing spreading of stream
• CPC Class Codes: H01J 23/083 Electrostatic focusing arrangements
• CPC Class Codes: H01J 23/087 Magnetic focusing arrangements

Abstract

A charged-particle beam control system includes a plurality of external magnets that generate an axially-varying longitudinal magnetic (AVLM)/axially-varying quadrupole magnetic (AVQM) field. A plurality of external electrode geometries generates an axially-varying longitudinal electrostatic (AVLE)/axially-varying quadrupole electrostatic (AVQE) field. The external electrode geometries and magnets control and confine a charged-particle beam of elliptic cross-section.

Claims

1. A charged-particle beam control system comprising:

a plurality of external magnets that generate an axially-varying longitudinal magnetic (AVLM)/axially-varying quadrupole magnetic (AVQM) field;

a plurality of external electrode geometries that generate an axially-varying longitudinal electrostatic (AVLE)/axially-varying quadrupole electrostatic (AVQE) field;

wherein said external electrode geometries and magnets control and confine a charged-particle beam of elliptic cross-section; and

a depressed collector that collects the charged-particle beam.

2. The charged-particle beam control system of claim 1, wherein the AVLM field aspect ratio parameter takes the critical value r_m=r_crit such that the magnitude of the beam envelope twist angle θ

approaches its minimum value.

3. The charged-particle beam control system of claim 2, wherein the AVLM field aspect ratio parameter r_m takes a value greater than 0.01 r_crit and less than 100 r_crit.

4. The charged-particle beam control system of claim 1, wherein the external magnets and electrode geometries enforce laminar flow of the beam from emission, through a charged-particle diode, and into a beam transport tunnel.

5. The charged-particle beam control system of claim 1, wherein the external magnets and electrode geometry enforce compression of the charged-particle beam.

7. The charged-particle beam control system of claim 1, wherein the depressed collector for a charged-particle beam comprising:

one or more electrodes; and

a collection surface onto which a beam impacts wherein said electrodes and collection surface create an electric field that enforce a flow profile in the beam that is substantially similar to a reversed Child-Langmuir flow.

8. The depressed collector of claim 7, wherein said charged-particle beam possesses an elliptic cross-section.

9. The depressed collector of claim 7, wherein said charged-particle beam possesses a uniform transverse density profile.

10. The depressed collector of claim 9, wherein the collector efficiency exceeds 90%.

6. The charged-particle beam control system of claim 6, wherein the area expansion factor is greater than 1.01 and less than 10000.

11. A method of forming a charged-particle beam control system comprising:

forming a plurality of external magnets that generate an axially-varying longitudinal magnetic (AVLM)/axially-varying quadrupole magnetic (AVQM) field;

forming a plurality of external electrode geometries that generate an axially-varying longitudinal electrostatic (AVLE)/axially-varying quadrupole electrostatic (AVQE) field, wherein said external electrode geometries and magnets control and confine a charged-particle beam of elliptic cross-section; and

forming a depressed collector that collects the charged-particle beam.

12. The method of claim 11, wherein the AVLM field aspect ratio parameter takes the critical value r_m=r_crit such that the magnitude of the beam envelope twist angle θ

approaches its minimum value.

13. The method of claim 12, wherein the AVLM field aspect ratio parameter r_m takes a value greater than 0.01 r_crit and less than 100 r_crit.

14. The method of claim 11, wherein the external magnets and electrode geometries enforce laminar flow of the beam from emission, through a charged-particle diode, and into a beam transport tunnel.

15. The method of claim 11, wherein the external magnets and electrode geometry enforce compression of the charged-particle beam.

17. The method of claim 11, wherein the method of forming a depressed collector for a charged-particle beam comprising:

providing one or more electrodes; and

forming a collection surface onto which the a beam impacts wherein said electrodes and collection surface create an electric field that enforce a flow profile in the beam that is substantially similar to a reversed Child-Langmuir flow.

18. The depressed collector of claim 17, wherein said charged-particle beam possesses an elliptic cross-section.

19. The depressed collector of claim 17, wherein said charged-particle beam possesses a uniform transverse density profile.

20. The depressed collector of claim 19, wherein the collector efficiency exceeds 90%.

16. The method of claim 16, wherein the area expansion factor is greater than 1.01 and less than 10000.