Interrupted particle source

Abstract

A synchrocyclotron includes magnetic structures to provide a magnetic field to a cavity, a particle source to provide a plasma column to the cavity, where the particle source has a housing to hold the plasma column, and where the housing is interrupted at an acceleration region to expose the plasma column, and a voltage source to provide a radio frequency (RF) voltage to the cavity to accelerate particles from the plasma column at the acceleration region.

What is claimed is: 
     
       1. A synchrocyclotron comprising:
 magnetic structures to provide a magnetic field to a cavity; 
 a particle source to provide comprising cathodes for generating a plasma column to in the cavity, the particle source having a housing to hold the plasma column, the housing being interrupted at an acceleration region to expose the plasma column, wherein the housing is interrupted such that the housing is completely separated at the acceleration region or such that a part of the housing is physically connected at the acceleration region; and 
 a voltage source to provide a radio frequency (RF) voltage to the cavity to accelerate particles from the plasma column at the acceleration region; 
 wherein, in a case that part of the housing is physically connected, the part of the housing has structure that allows particles accelerated from the plasma column to perform at least one turn without impinging on the part of the housing. 
 
     
     
       2. The synchrocyclotron of  claim 1 , wherein the magnetic field is above 2 Tesla (T), and the particles move from the plasma column outwardly in spirals with radii that progressively increase. 
     
     
       3. The synchrocyclotron of  claim 1 , wherein the housing comprises two portions that are completely separated at the acceleration region to expose the plasma column. 
     
     
       4. The synchrocyclotron of  claim 1 , wherein the voltage source comprises a first dee that is electrically connected to an alternating voltage and a second dee that is electrically connected to ground; and
 wherein at least part of the particle source passes through the second dee. 
 
     
     
       5. The synchrocyclotron of  claim 1 , further comprising a stop in the acceleration region, the stop for blocking acceleration of at least some of the particles from the plasma column. 
     
     
       6. The synchrocyclotron of  claim 5 , wherein the stop is substantially orthogonal to the acceleration region and is configured to block certain phases of particles from the plasma column. 
     
     
       7. The synchrocyclotron of  claim 1 ,further comprising:
 cathodes for use in generating the plasma column, wherein the cathodes being are operable to pulse a voltage to ionize gas to generate the plasma column; and 
 wherein the cathodes are not heated by an external heat source. 
 
     
     
       8. The synchrocyclotron of  claim 7 , wherein the cathodes are configured to pulse at voltages between about 1 kV to about 4 kV. 
     
     
       9. The synchrocyclotron of  claim 7 , further comprising:
 a circuit to couple voltage from the RF voltage to the at least one of the cathodes. 
 
     
     
       10. The synchrocyclotron of  claim 9 , wherein the circuit comprises a capacitive circuit. 
     
     
       11. The synchrocyclotron of  claim 1 , wherein the magnetic structures comprise magnetic yokes, wherein the voltage source comprises a first dee that is electrically connected to an alternating voltage and a second dee that is electrically connected to ground, wherein the first dee and the second dee form a tunable resonant circuit, and wherein the cavity comprises a resonant cavity containing the tunable resonant circuit. 
     
     
       12. A synchrocyclotron comprising:
 a tube containing a gas; 
 a first cathode adjacent to a first end of the tube; and 
 a second cathode adjacent to a second end of the tube, the first and second cathodes applying voltage to the tube to form a plasma column from the gas; 
 wherein particles are available to be drawn from the plasma column for acceleration; and 
 a circuit to couple energy from an external a radio frequency (RF) field to at least one of the cathodes; 
 wherein the tube is interrupted at an acceleration region where the particles are accelerated to expose the plasma column, wherein the tube is interrupted such that the tube is completely separated into two parts at the acceleration region or such that a part of the tube is physically connected at the acceleration region where the particles are accelerated; 
 wherein, in a case that part of the tube is physically connected, the part of the tube has structure that allows particles accelerated from the plasma column to perform at least one turn without impinging on the part of the tube. 
 
     
     
       13. The synchrocyclotron of  claim 12 , wherein the first cathode and the second cathode are not heated by an external source. 
     
     
       14. The synchrocyclotron of  claim 13 , further comprising:
 a voltage source to provide the RF field, the RF field for accelerating the particles from the plasma column at the acceleration region where the particles are accelerated. 
 
     
     
       15. The synchrocyclotron of  claim 14 , wherein the energy comprises a portion of the RF field provided by the voltage source. 
     
     
       16. The synchrocyclotron of  claim 13 , wherein the circuit comprises a capacitor to couple energy from the external RF field to at least one of the first cathode and the second cathode. 
     
     
       17. The synchrocyclotron of claim  13  12, wherein the tube comprises a first portion part and a second portion that are completely separated at the acceleration region where the particles are accelerated part that are separated by a space that is between 1 mm and 3 mm. 
     
     
       18. The synchrocyclotron of  claim 13 , further comprising:
 a stop at the acceleration region, the stop to block at least one phase of the particles from further acceleration. 
 
     
     
       19. The synchrocyclotron of claim  13  12, further comprising:
 a voltage source to provide the RF field to the plasma column, the RF field for accelerating the particles from the plasma column at the acceleration region where the particles are accelerated, wherein the RF field comprises voltage that is less than 15 kV; and 
 magnetic yokes structures to provide a magnetic field that crosses the acceleration region where the particles are accelerated, the magnetic field being greater than about 2 Tesla (T). 
 
     
     
       20. The synchrocyclotron of  claim 12 , wherein the first cathode is on a different side of the acceleration region than the second cathode. 
     
     
       21. A synchrocyclotron comprising:
 a Penning ion gauge (PIG) source comprising a first tube portion and a second tube portion, the first tube portion having a first cathode and the second tube portion having a second cathode, the first cathode and the second cathode for holding generating a plasma column that extends across an acceleration region from which particles are accelerated from the plasma column; and 
 a voltage source to provide a voltage at the acceleration region, the voltage for accelerating particles out of the plasma column at the acceleration region; 
 wherein the first tube portion is completely separated from the second tube portion at the acceleration region or a connection exists between the first tube portion and the second tube portion at the acceleration region; 
 wherein, in a case that the connection exists, the connection has structure that allows particles accelerated from the plasma column to perform at least one turn without impinging on the connection. 
 
     
     
       22. The synchrocyclotron of  claim 21 , wherein the PIG source comprises a physical connection between a part of the first tube portion and the second tube portion, the physical connection enabling particles accelerating out of the plasma column to complete a first turn upon escaping from the plasma column without running into the physical connection. 
     
     
       23. The synchrocyclotron of  claim 21 , wherein the PIG source passes through a first dee that is electrically connected to ground, and wherein a second dee that is electrically connected to an alternating voltage source provides the voltage at the acceleration region. 
     
     
       24. The synchrocyclotron of  claim 21 , further comprising:
 magnetic yokes structures that define border a cavity containing the acceleration region, the magnetic yokes structures for generating a magnetic field across the acceleration region. 
 
     
     
       25. The synchrocyclotron of  claim 24 , wherein the magnetic field is at least 2 Tesla (T). 
     
     
       26. The synchrocyclotron of  claim 25 , wherein the magnetic field is at least 10.5 T. 
     
     
       27. The synchrocyclotron of claim  26  21, wherein the voltage comprises a radio frequency (RF) voltage that is less than 15 kV. 
     
     
       28. The synchrocyclotron of  claim 21 , further comprising one or more electrodes for use in accelerating structures to direct the particles out of the particle accelerator. 
     
     
       29. The synchrocyclotron of  claim 21 , further comprising:
 at least one cathode for use in generating the plasma column, the at least one cathode comprising wherein the first cathode comprises a cold cathode and the second cathode comprises a cold cathode; and 
 a capacitive circuit to couple at least some of the voltage to the at least one cathode. 
 
     
     
       30. The synchrocyclotron of  claim 21 , wherein the at least one cathode is first cathode and the second cathode are configured to pulse voltage to generate the plasma column from gas in the first tube portion and the second tube portion. 
     
     
       31. A particle accelerator comprising:
 a tube containing a gas; 
 a first cathode adjacent to a first end of the tube; 
 a second cathode adjacent to a second end of the tube, the first and second cathodes applying voltage to the tube to form a plasma column from the gas; 
 wherein particles are available to be drawn from the plasma column for acceleration; 
 a circuit to couple energy from an external a radio frequency (RF) field to at least one of the cathodes; and 
 magnetic structures to provide a magnetic field that crosses an acceleration region where the particles are accelerated, the magnetic field being greater than about 2 Tesla (T); 
 wherein the tube is interrupted at the acceleration region where the particles are accelerated to expose the plasma column, and wherein the tube is interrupted such that the tube is completely separated into two parts at the acceleration region or such that a part of the tube is physically connected at the acceleration region where the particles are accelerated; 
 wherein, in a case that part of the tube is physically connected, the part of the tube has structure that allows particles accelerated from the plasma column to perform at least one turn without impinging on the part of the tube. 
 
     
     
       32. The particle accelerator of  claim 31 , wherein the first cathode and the second cathode are not heated by an external source. 
     
     
       33. The particle accelerator of  claim 32 , wherein the circuit comprises a capacitor to couple energy from the external RF field to at least one of the first cathode and the second cathode. 
     
     
       34. The particle accelerator of  claim 32 , wherein the tube comprises a first portion and a second portion that are completely separated at the acceleration region where the particles are accelerated. 
     
     
       35. The particle accelerator of claim  32  31, further comprising:
 a stop at the acceleration region where the particles are accelerated, the stop to block at least one phase of the particles from further acceleration. 
 
     
     
       36. The particle accelerator of claim  32  31, further comprising:
 a voltage source to provide the RF field to the plasma column, the RF field for accelerating the particles from the plasma column at the acceleration region where the particles are accelerated, wherein the RF field comprises voltage that is less than 15 kV; and 
 wherewherein the magnetic structures comprise magnetic yokes. 
 
     
     
       37. The particle accelerator of  claim 31 , wherein the first cathode is on a different side of the acceleration region where the particles are accelerated than the second cathode. 
     
     
       38. The particle accelerator of  claim 37 , further comprising:
 a voltage source to provide the RF field, the RF field for accelerating the particles from the plasma column at the acceleration region where the particles are accelerated. 
 
     
     
       39. The particle accelerator of  claim 33 , wherein the energy comprises a portion of the RF field provided by the voltage source. 
     
     
       40. The particle accelerator of  claim 31 , wherein the magnetic field is greater than 8 T. 
     
     
       41. The particle accelerator of  claim 31 , wherein the magnetic field is greater than 10.5 T. 
     
     
       42. A synchrocyclotron comprising:
 ferromagnetic pole pieces that border a cavity containing an acceleration region;   electrical coils adjacent to the ferromagnetic pole pieces to produce a magnetic field of at least 2 Tesla (T) within the cavity; and   a Penning ion gauge (PIG) source comprised of a first part and a second part that are completely separated at the acceleration region to allow extraction of charged particles from a plasma column for acceleration, the first part having a first cathode and the second part having a second cathode, the first cathode and the second cathode for generating the plasma column.   
     
     
       43. The synchrocyclotron of claim 42, wherein the magnetic field is at least 8 T. 
     
     
       44. The synchrocyclotron of claim 42, further comprising:
 a voltage system to provide radio frequency (RF) voltage to the cavity, the voltage system comprising a first dee that is electrically connected to an alternating voltage and a second dee that is electrically connected to ground;   wherein at least part of the PIG source passes through the second dee.   
     
     
       45. A synchrocyclotron comprising:
 ferromagnetic pole pieces that border a cavity containing an acceleration region;   electrical coils adjacent to the ferromagnetic pole pieces to produce a magnetic field of at least 2 Tesla (T) within the cavity;   a Penning ion gauge (PIG) source comprised of a first part and a second part that are completely separated at the acceleration region to allow extraction of charged particles from a plasma column for acceleration; and   a stop in the acceleration region, the stop for blocking at least some of the charged particles.   
     
     
       46. The synchrocyclotron of claim 45, wherein the stop is substantially orthogonal to the acceleration region and is configured to block certain phases of the charged particles. 
     
     
       47. The synchrocyclotron of claim 42, wherein the first cathode and the second cathode are operable to pulse a voltage to ionize gas to generate the plasma column; and
 wherein the first and second cathodes are not heated by an external heat source.   
     
     
       48. The synchrocyclotron of claim 47, wherein the first and second cathodes are controllable to pulse at voltages between about 1 kV to about 4 kV. 
     
     
       49. The synchrocyclotron of claim 48, further comprising:
 a circuit to couple voltage to at least one of the first and second cathodes.   
     
     
       50. The synchrocyclotron of claim 49, wherein the circuit comprises a capacitive circuit. 
     
     
       51. A synchrocyclotron comprising:
 ferromagnetic pole pieces that border a cavity containing an acceleration region in which charged particles are accelerated, the cavity containing a magnetic field of at least 2 Tesla (T);   a particle source comprising a first part and a second part, the first part having a first cathode and the second part having a second cathode, the first part and the second part being completely separated at the acceleration region;   accelerating electrodes to provide a radio frequency (RF) voltage to the acceleration region to extract the charged particles, the RF voltage sweeping over a frequency range; and   circuitry to couple energy from the RF voltage to at least one of the first cathode or the second cathode.   
     
     
       52. The synchrocyclotron of claim 51, wherein the cavity contains a magnetic field that is at least 8 T. 
     
     
       53. The synchrocyclotron of claim 51, wherein the cavity contains a magnetic field that is at least 10.5 T. 
     
     
       54. The synchrocyclotron of claim 51, further comprising:
 a voltage system to provide radio frequency (RF) voltage to the cavity, the voltage system comprising a first dee that is electrically connected to an alternating voltage and a second dee that is electrically connected to ground;   wherein at least part of the particle source passes through the second dee.   
     
     
       55. The synchrocyclotron of claim 51, further comprising a stop in the acceleration region, the stop for blocking at least some of the charged particles. 
     
     
       56. The synchrocyclotron of claim 55, wherein the stop is substantially orthogonal to the acceleration region and is configured to block certain phases of the charged particles. 
     
     
       57. The synchrocyclotron of claim 51, wherein the first and second cathodes are controllable to pulse at voltages between about 1 kV to about 4 kV. 
     
     
       58. The synchrocyclotron of claim 51, wherein the circuitry comprises a capacitive circuit. 
     
     
       59. A synchrocyclotron comprising:
 ferromagnetic pole pieces that border a cavity containing an acceleration region;   a voltage system to provide radio frequency (RF) voltage to the cavity,   electrical coils around part of the ferromagnetic pole pieces to produce a magnetic field having a magnitude of at least 2 Tesla (T) within the cavity; and   a particle source that is completely separated at least at the acceleration region to allow extraction of charged particles from a plasma column for acceleration in response to the RF voltage, the particle source comprising a first part and a second part, the first part having a first cathode and the second part having a second cathode, the first and second cathodes for generating the plasma column.   
     
     
       60. The synchrocyclotron of claim 59, wherein the magnetic field is at least 8 T within the cavity. 
     
     
       61. The synchrocyclotron of claim 59, wherein the voltage system comprises a first dee that is electrically connected to an alternating voltage and a second dee that is electrically connected to ground; and
 wherein the RF voltage provided to the cavity is less than 15 kV.   
     
     
       62. The synchrocyclotron of claim 59, wherein the first part and the second part are separated for distances above and below the acceleration region. 
     
     
       63. The synchrocyclotron of claim 59, wherein the plasma column is produced from a gas, and wherein flow of the gas into the synchrocyclotron is less than one standard cubic centimeter per minute (SCCM). 
     
     
       64. A synchrocyclotron comprising:
 ferromagnetic pole pieces that border a cavity containing an acceleration region;   a voltage system to provide radio frequency (RF) voltage to the cavity,   electrical coils around part of the ferromagnetic pole pieces to produce a magnetic field having a magnitude of at least 2 Tesla (T) within the cavity;   a particle source that is interrupted at least at the acceleration region to allow extraction of charged particles from a plasma column for acceleration in response to the RF voltage; and   one or more stops at the acceleration region, the one or more stops to block at least one phase of the charged particles extracted from the particle source from further acceleration.