RF source protection

Patent metadata

Field	Value
Publication number	US-12414221-B2
Application number	US-202118247992-A
Country	US
Kind code	B2
Filing date	Oct 8, 2021
Priority date	Oct 9, 2020
Publication date	Sep 9, 2025
Grant date	Sep 9, 2025

Abstract

A method of determining a design of a transmission waveguide, the method comprising: providing a system comprising a transmission waveguide connected at a first end thereof to an RF source; generating an electromagnetic field in the system by application of RF energy of a harmonic frequency of the RF source to the transmission waveguide; determining whether a reference location in the RF source meets a requirement relating directly or indirectly to an electromagnetic field in the RF source; and if the requirement is met, outputting the current design of the transmission waveguide as its design.

First claim

The invention claimed is:

1. A method of determining a design of a transmission waveguide, the method comprising:
providing a system comprising a transmission waveguide connected at a first end thereof to an RF source;
generating an electromagnetic field in the system by application of RF energy of a harmonic frequency of the RF source to the transmission waveguide;
determining whether a reference location in the RF source meets a requirement relating directly or indirectly to the electromagnetic field in the RF source, wherein the reference location is a part of the RF source adversely affected by absorption of the RF energy;
determining the design of the transmission waveguide based on the requirement being met; and
outputting the determined design.

2. The method of claim 1 , wherein responsive to the requirement not being met, the method further comprises:
altering the transmission waveguide by one or more of:
adding an RF attenuator to the transmission waveguide;
modifying an RF attenuator in the transmission waveguide;
moving a position of an RF attenuator in the transmission waveguide; or
altering a length of the transmission waveguide;

generating an electromagnetic field in the altered transmission waveguide by application of RF energy of a harmonic frequency capable of detrimentally affecting the RF source to the altered transmission waveguide; and
determining whether the reference location in the RF source meets the requirement.

3. The method of claim 2 , further comprising:
repeating the method of claim 2 until the requirement is met.

4. The method of claim 2 , wherein the requirement changes from an initial requirement before the transmission waveguide is altered to a modified requirement after the transmission waveguide is altered, and wherein the modified requirement is different from the initial requirement, wherein the modified requirement comprises at least one of: i) a value at the reference location that is lower than a first value determined before altering the transmission waveguide, or ii) a distance from the reference location to a nearest maxima of the electromagnetic field that is greater than a first distance determined before altering the transmission waveguide.

5. The method of claim 4 , wherein the modified requirement is dependent on a value at the reference location before altering the transmission waveguide.

6. The method of claim 5 , wherein the value is a temperature field value or an electromagnetic field value and/or a value derived either directly or indirectly therefrom having a measurable detrimental effect on an RF performance of the RF source, and/or wherein the value is related to a threshold attribute of at least a part of the RF source.

7. The method of claim 5 , wherein a first value at the reference location is determined before the transmission waveguide is altered, and wherein the modified requirement is that a second value at the reference location determined after altering the transmission waveguide is lower than the first value.

8. The method of claim 5 , wherein a nearest maxima of the electromagnetic field to the reference location before the transmission waveguide is altered is determined to be a first distance from the reference location, and wherein the modified requirement is that the nearest maxima to the reference location after the transmission waveguide is altered is a greater distance from the reference location than the first distance.

9. The method of claim 2 , wherein altering the transmission waveguide comprises:
increasing or decreasing the length of the transmission waveguide by less than a quarter of a wavelength of the harmonic frequency of the RF source.

10. The method of claim 2 , wherein altering the transmission waveguide includes adding a spacer or a waveguide section to the transmission waveguide.

11. The method of claim 1 , wherein the requirement is an electromagnetic field requirement or a temperature field requirement.

12. The method of claim 1 , wherein the requirement is that a nearest maxima of the electromagnetic field to the reference location is located above a threshold distance from the reference location.

13. The method of claim 1 , wherein the method is simulated in a computer model.

14. The method of claim 1 , wherein the reference location is a locus of points in the RF source.

15. The method of claim 1 , wherein the reference location is a single point in the RF source.

16. The method of claim 2 , wherein the RF source is a magnetron.

17. The method of claim 16 , wherein the reference location is collocated with a part or whole of a cathode of the magnetron.

18. The method of claim 16 , wherein the system further comprises:
an accelerating waveguide, wherein the transmission waveguide is connected at a second end thereof to the accelerating waveguide.

19. The method of claim 16 , wherein a harmonic frequency of the magnetron is a second harmonic frequency.

20. The method of claim 19 , wherein the harmonic frequency has a detrimental effect on the RF source, and wherein the harmonic frequency includes the second harmonic frequency of the magnetron when the magnetron is being used as the RF source.

21. The method of claim 19 , wherein the RF attenuator is configured to attenuate a greater proportion of RF waves of the harmonic frequency of the magnetron than RF waves of the harmonic frequency of the RF source.

22. The method of claim 2 , wherein the RF attenuator comprises an RF absorber.

23. The method of claim 22 , wherein the RF absorber comprises:
a coating configured to absorb RF waves of the harmonic frequency of the RF source.

24. The method of claim 22 , wherein the RF attenuator comprises:
a waveguide section comprising the RF absorber.

25. The method of claim 2 , wherein the RF attenuator is configured to pass RF waves of the harmonic frequency of the RF source in a first direction.

26. The method of claim 25 , wherein the RF attenuator comprises an isolator.

27. The method of claim 2 , wherein the RF attenuator comprises:
a low-pass filter configured to pass waves of the harmonic frequency of the RF source and attenuate waves of the harmonic frequency.

28. The method of claim 27 , wherein the low-pass filter comprises a waffle-iron filter.

29. The method of claim 2 , wherein the RF attenuator comprises:
an RF resonator cavity configured to resonate RF waves at the harmonic frequency of the RF source.

30. The method of claim 29 , wherein the RF resonator cavity comprises an RF absorber.

31. A method of fabricating a transmission waveguide, the method comprising:
determining a design of the transmission waveguide; and
fabricating the transmission waveguide having the design, wherein determining the design includes:
providing a system comprising a transmission waveguide connected at a first end thereof to an RF source;
generating an electromagnetic field in the system by application of RF energy of a harmonic frequency of the RF source to the transmission waveguide;
determining whether a reference location in the RF source meets a requirement relating directly or indirectly to the electromagnetic field in the RF source, wherein the reference location is a part of the RF source adversely affected by absorption of the RF energy; and
determining the design of the tr

Assignees

• Elekta ltd

Inventors

• Shinton Ian
• Doherty Peter
• Wooldridge Emma

Classifications

• H05H2277/11

  Radiotherapy · CPC title

• H01J25/54

  having only one cavity or other resonator, e.g. neutrode tubes · CPC title

• H01J23/207

  Tuning of single resonator · CPC title

• H05H2007/225

  coupled cavities arrangements · CPC title

• H01P1/39

  Hollow waveguide circulators · CPC title