TRANSMISSION ION CHAMBER

• US 3,852,610 A
• Filed: 02/26/1973
• Issued: 12/03/1974
• Est. Priority Date: 02/26/1973
• Status: Expired due to Term

• Current Assignee: Raymond D. Mcintyre
• Original Assignee: Raymond D. Mcintyre
• Inventors: McIntyre, Raymond D.
• Primary Examiner(s): Lawrence, James W.
• Assistant Examiner(s): Willis, Davis L.
• Application Number:
  US05/335,633
• Time in Patent Office: 645 Days
• Field of Search: 250/320,374,382,384,385,389 313/93
• US Class Current: 250/385.1
• CPC Class Codes: A61N 5/1048 Monitoring, verifying, controlling systems and methods
• CPC Class Codes: G01T 1/29 Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
• CPC Class Codes: H01J 47/02 Ionisation chambers

Abstract

A linear particle accelerator having detection apparatus for detecting the presence of and correcting for beam misalignment. The linear accelerator includes a charged particle accelerator system and deflection coils for changing both the positional and angular displacement of a charged particle beam. A target is disposed in the particle beam path for emitting X-rays upon being struck by the charged particles. The photon field developed by the target takes the form of a forward-peaked lobe configuration extending from the target. An ionization chamber is disposed in the radiation field for developing electrical signals responsive to changes in the lobe field. The ionization chamber includes a housing member, and insulative sheet, such as a sheet of thin glass or mica, is supported within the housing member. A pattern of detection electrodes is formed on the insulative sheet by vacuum deposition or other similar process. A high voltage electrode comprising a sheet of conductive material is supported within the housing member in spaced parallel relationship with the detection electrodes.

Claims

1. In a particle accelerator system including means for forming and projecting a beam of charged particles along a substantially linear path, and target means disposed in said beam path for developing a radiation field upon being struck by said charged particles:

ionization chamber means disposed in said radiation field and including a housing member;

an insulative support sheet mounted within said housing member, said insulative support sheet having first and second oppositely facing surfaces;

first electrode means comprising a film of conductive material secured to at least a portion of one of said surfaces of said insulative support sheet and positioned in superimposed parallel relationship with respect to said one of said surfaces;

second electrode means spaced apart from said first electrode means, said second electrode means comprising a sheet of conductive material supported by said housing member in spaced parallel relationship with respect to said conductive film of said first electrode means;

third electrode means comprising a film of conductive material secured to at least a portion of the other of said surfaces of said insulative support sheet and positioned in superimposed parallel relationship with respect to said other of said surfaces;

fourth electrode means spaced apart from said third electrode means, said fourth electrode means comprising a sheet of conductive material supported by said housing member in spaced parallel relationship with respect to said conductive film of said third electrode means; and

enclosure means supported by said housing member for maintaining an ionizable gas in the spaced region between said electrode means.

2. An apparatus as disclosed in claim 1 wherein said first electrode means takes the form of plural strips of conductive material secured to portions of said one surface of said insulative sheet and positioned in superimposed parallel relationship with respect to said surface.

3. An apparatus as disclosed in claim 1 wherein said film of conductive material takes the form of a coating of conductive material bonded to said one surface of said insulative support sheet. 4. An apparatus as disclosed in claim 1 wherein said film of conductive material takes the form of a vacuum deposited coating of conductive material bonded to said one surface of said insulative support sheet.

5. An apparatus as disclosed in claim 1 wherein said insulative support sheet comprises of a mica sheet and said film of conductive material takes the form of a coating of conductive material bonded to one of the surfaces of said mica sheet.

6. An apparatus as disclosed in claim 1 wherein said insulative support sheet comprises a glass sheet and said film of conductive material takes the form of a coating of conductive material bonded to one of the surfaces of said glass sheet.

7. An apparatus as disclosed in claim 1 wherein said second electrode means takes the form of a conductive foil.

8. An apparatus as disclosed in claim 1 wherein both said films of conductive material take the form of a coating of conductive material bonded to the surfaces of said insulative support sheet.

9. A radiation apparatus comprising a charged particle accelerator for forming and projecting a beam of charged particles along a path;

target means disposed in said path, said target means being capable of generating a radiation field upon being struck by said beam of charged particles;

ionization chamber means disposed in said radiation field, said ionization chamber means comprising a sealed enclosure for containing an ionizable gas therewithin;

a radiation resistant electrically insulating support structure mounted within said enclosure;

a plurality of coating electrodes comprising electrically conductive material coated on said support structure in discontiguous relation to each other; and

an electrode comprising an electrically conductive surface disposed in said enclosure spaced apart from said coating electrodes;

said coating electrodes being arranged in a pattern on said support structure such that the configuration of said radiation field in said ionization chamber means is determinative of the presence of an ionization current between said spaced apart electrode and any one of said coating electrodes.

10. The apparatus of claim 9 further comprising electric circuitry responsive to the presence of an ionization current between said spaced apart electrode and any one of said coating electrodes, and servomechanism means responsive to said electric circuitry for correcting said beam path whereby a constant configuration of said radiation field can be maintained.

11. The apparatus of claim 9 wherein said support structure comprises a solid dielectric material.

12. The apparatus of claim 9 wherein said support structure comprises a mica sheet.

13. The apparatus of claim 9 wherein said support structure comprises a glass sheet.

14. The apparatus of claim 9 wherein said coating electrodes are bonded to said support structure by a vacuum deposition bond.

15. The apparatus of claim 9 wherein said coating electrodes are substantially coplanar with each other and said spaced apart electrode is disposed parallel to said coplanar electrodes.

16. The apparatus of claim 9 wherein said spaced apart electrode comprises a metal foil.

17. The apparatus of claim 16 wherein said metal is aluminum.

18. The apparatus of claim 9 wherein said support structure comprises a dielectric plate having two oppositely facing parallel sides, said plurality of coating electrodes being bonded to one side of said plate and said spaced apart electrode being adjacent said one side of said plate;

said apparatus further comprising another plurality of coating electrodes, said other coating electrodes being bonded to the other side of said plate, and another electrode comprising an electrically conductive surface disposed in said enclosure, said other electrode being adjacent said other side of said dielectric plate and spaced apart from said other coating electrodes.

19. An ionization chamber comprising a sealed enclosure for containing an ionizable gas therewithin, a radIation resistant electrically insulating support structure mounted within said enclosure, a plurality of coating electrodes comprising electrically conductive material coated on said support structure in discontiguous relation to each other, and an electrode comprising an electrically conductive surface disposed in said enclosure spaced apart from said coating electrodes.

20. The ionization chamber of claim 19 further comprising electrically conductive path means along said support structure from each coating electrode to a unique terminal corresponding to said coating electrode, each of said terminals being capable of coupling an electrical signal from one of said coating electrodes to means responsive to said signal whenever an ionization current is present between said spaced apart electrode and said coating electrode.

21. The ionization chamber of claim 20 wherein said terminals are located adjacent the perimeter of said dielectric support structure.

22. The ionization chamber of claim 19 wherein said support structure comprises a solid dielectric material.

23. The ionization chamber of claim 19 wherein said support structure comprises a mica sheet.

24. The ionization chamber of claim 19 wherein said support structure comprises a glass sheet.

25. The ionization chamber of claim 19 wherein said coating electrodes are bonded to said support structure by a vacuum deposition bond.

26. The ionization chamber of claim 19 wherein said coating electrodes are substantially coplanar with each other and said spaced apart electrode is disposed parallel to said coplanar electrodes.

27. The ionization chamber of claim 19 wherein said spaced apart electrode comprises a metal foil.

28. The ionization chamber of claim 27 wherein said metal is aluminum.

29. The ionization chamber of claim 19 wherein said support structure comprises a dielectric plate having two oppositely facing parallel sides, said plurality of coating electrodes being bonded to one side of said dielectric plate and said spaced apart electrode being adjacent said one side of said dielectric plate;

said ionization chamber further comprising another plurality of coating electrodes, said other coating electrodes being bonded to the other side of said dielectric plate, and another electrode comprising an electrically conductive surface disposed in said enclosure, said other electrode being adjacent said other side of said dielectric plate and spaced apart from said other coating electrodes.