Radio-frequency electrode and cyclotron configured to reduce radiation exposure

Patent metadata

Field	Value
Publication number	US-9894747-B2
Application number	US-201614995772-A
Country	US
Kind code	B2
Filing date	Jan 14, 2016
Priority date	Jan 14, 2016
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

Radio-frequency (RF) electrode for a cyclotron. The RF electrode includes a hollowed dee having first and second surfaces that oppose each other and define a gap therebetween. The hollowed dee is configured to be electrically controlled to direct a beam of charged particles through the gap and along an orbit plane of the cyclotron. The orbit plane extends parallel to the first and second surfaces through the gap. The RF electrode also includes a bridge structure that is coupled to and extends away from the hollowed dee. The bridge structure includes a side wall that defines an interior cavity of the bridge structure. The side wall has a particle opening therethrough that coincides with or is proximate to the orbit plane such that the particle opening receives neutral particles from an orbit of the charged particles.

First claim

What is claimed is:

1. A radio-frequency (RF) electrode for a cyclotron, the RF electrode comprising:
a hollowed dee comprising first and second plate sections that oppose each other and define a gap therebetween, the hollowed dee configured to be disposed within an acceleration chamber of a cyclotron in which a beam of charged particles is directed through the gap and along an orbit plane of the cyclotron, the orbit plane extending through the gap and being essentially parallel to the first and second plate sections; and
a bridge structure supporting and extending away from the hollowed dee, the bridge structure including a side wall having a particle opening therethrough that coincides with or is proximate to the orbit plane such that the particle opening receives neutral particles that are generated from the beam of the charged particles.

2. The RF electrode of claim 1 , wherein the side wall is a first side wall and the bridge structure includes a second side wall that opposes the first side wall with an interior cavity of the bridge structure therebetween, the second side wall facing the particle opening of the first side wall, wherein the particle opening is an elongated particle opening in which a length of the particle opening measured parallel to the orbit plane is at least five times (5×) a height of the particle opening measured perpendicular to the orbit plane.

3. The RF electrode of claim 1 , further comprising an interception panel that is configured to be coupled to the bridge structure and positioned to receive the neutral particles that project through the particle opening along the orbit plane.

4. The RF electrode of claim 3 , wherein the bridge structure is configured to substantially isolate the interception panel from electromagnetic fields in the acceleration chamber.

5. The RF electrode of claim 3 , wherein the bridge structure comprises a conductive material and the interception panel comprises a blocking material;
wherein the blocking material and the conductive material are capable of generating respective radioisotopes when neutral hydrogen particles are incident thereon, the blocking material being configured such that the radioisotopes of the blocking material have shorter half-lives than the radioisotopes of the conductive material; and
wherein the blocking material and the conductive material are capable of generating prompt radiation when the neutral hydrogen particles are incident thereon, the blocking material being configured such that the prompt radiation from the blocking material is less than the prompt radiation from the conductive material.

6. The RF electrode of claim 3 , wherein the side wall defines an interior cavity of the bridge structure, the interception panel being disposed within the interior cavity.

7. The RF electrode of claim 4 , wherein the interception panel is secured directly to the bridge structure within the interior cavity.

8. The RF electrode of claim 3 , wherein the interception panel includes at least one of graphite or tungsten.

9. The RF electrode of claim 1 , wherein the bridge structure includes an elongated stem, the elongated stem extending away from the hollowed dee, the elongated stem including the particle opening, the particle opening having a first dimension and a second dimension, the first dimension extending parallel to the orbit plane and the second dimension extending perpendicular to the orbit plane, the first dimension being at least three times (3×) the second dimension.

10. A cyclotron comprising:
an electrical field system and a magnetic field system configured to direct a beam of charged particles along an orbit plane within an acceleration chamber, wherein the magnetic field system includes a pair of pole tops positioned in the acceleration chamber that oppose each other, the orbit plane extending between and generally parallel to the pole tops, the electrical field system including a plurality of RF electrodes having hollowed dees positioned between the pole tops;
wherein at least one of the RF electrodes includes a bridge structure that is coupled to and extends away from the corresponding hollowed dee, the bridge structure including a side wall having a particle opening therethrough that coincides with or is proximate to the orbit plane, the particle opening being positioned to receive neutral particles generated from the beam of the charged particles within the acceleration chamber, wherein the cyclotron also includes an interception panel that is positioned relative to the particle opening to receive the neutral particles.

11. The cyclotron of claim 10 , wherein the acceleration chamber includes an inner spatial region between the pole tops and an outer spatial region that surrounds the inner spatial region, the bridge structure being disposed within the outer spatial region.

12. The cyclotron of claim 10 , wherein the side wall is a first side wall and the bridge structure includes a second side wall that opposes the first side wall with an interior cavity of the bridge structure therebetween, the interception panel being positioned within the interior cavity.

13. The cyclotron of claim 12 , wherein the interception panel is secured directly to the bridge structure within the interior cavity.

14. The cyclotron of claim 12 , wherein the bridge structure is configured to substantially isolate the interception panel from electromagnetic fields in the acceleration chamber.

15. The cyclotron of claim 10 , wherein the bridge structure comprises a conductive material and the interception panel comprises a blocking material;
wherein the blocking material and the conductive material are capable of generating respective radioisotopes when neutral hydrogen particles are incident thereon, the blocking material being configured such that the radioisotopes of the blocking material have shorter half-lives than the radioisotopes of the conductive material; and
wherein the blocking material and the conductive material are capable of generating prompt radiation when the neutral hydrogen particles are incident thereon, the blocking material being configured such that the prompt radiation from the blocking material is less than the prompt radiation from the conductive material.

16. The cyclotron of claim 10 , wherein the particle opening has a first dimension and a second dimension, the first dimension extending parallel to the orbit plane and the second dimension extending perpendicular to the orbit plane, the first dimension being at least three times (3×) the second dimension.

17. A method comprising:
providing an RF electrode that includes a hollowed dee having first and second plate sections that oppose each other and define a gap therebetween, the RF electrode also including a bridge structure that is coupled to and extends away from the hollowed dee, the bridge structure including a side wall having a particle opening therethrough;
positioning the RF electrode within an acceleration chamber of a cyclotron, the cyclotron configured to direct a beam of charged particles along an orbit plane within the acceleration chamber, the RF electrode being positioned such that the orbit plane extends between the first and second plate sections and extends through or proximate to the particle opening of the side wall, the particle opening positioned to receive neutral particles that are generated from the beam of the charged particles during operation of the cyclotron; and
positioning an interception panel within the acceleration chamber to receive the neutral particles that project through the particle opening along t

Assignees

• Gen Electric

Inventors

• Paernaste Martin
• Baecklund Andreas
• Walenius Lars

Classifications

• H05H7/10 Primary

  Arrangements for ejecting particles from orbits · CPC title

• H05H13/005

  Cyclotrons · CPC title

• H05H7/12

  Arrangements for varying final energy of beam · CPC title

• H05H2007/122

  by electromagnetic means, e.g. RF cavities · CPC title

• H05H2007/025

  Radiofrequency systems · CPC title