Electron injector and free electron laser

Patent metadata

Field	Value
Publication number	US-9728931-B2
Application number	US-201415035674-A
Country	US
Kind code	B2
Filing date	Nov 27, 2014
Priority date	Dec 5, 2013
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

An injector arrangement for providing an electron beam. The injector arrangement comprises a first injector for providing electron bunches, and a second injector for providing electrons bunches. The injector arrangement is operable in a first mode in which the electron beam comprises electron bunches provided by the first injector only and a second mode in which the electron beam comprises electron bunches provided by the second injector only.

First claim

The invention claimed is:

1. An electron injector comprising:
a support structure arranged to support a photocathode;
a beam delivery system arranged to direct a beam of radiation from a radiation source onto a region of the photocathode thereby causing the photocathode to emit a beam of electrons;
an adjustment mechanism operable to change the region of the photocathode which is illuminated by the radiation beam; and
a steering unit operable to apply a force to the beam of electrons to alter its trajectory such that the electrons become substantially coincident with an axis of the electron injector.

2. The electron injector of claim 1 , wherein the steering unit comprises one or more electromagnets.

3. The electron injector of claim 1 , wherein the steering unit is downstream of an electron booster of the electron injector.

4. The electron injector of claim 1 , wherein the region of the photocathode which is illuminated by the radiation beam is separated from the axis of the electron injector.

5. The electron injector of claim 1 , wherein the beam delivery system is configured such that the radiation beam is not perpendicular to the photocathode when it is incident upon the photocathode.

6. The electron injector of claim 1 , wherein the adjustment mechanism comprises a radiation beam adjustment unit in the beam delivery system, the radiation beam adjustment unit being operable to change one or more properties of the radiation beam.

7. The electron injector of claim 6 , wherein the radiation beam adjustment unit is operable to change the direction of propagation of the radiation beam.

8. The electron injector of claim 1 , wherein the beam delivery system comprises a mirror arranged to reflect the radiation beam onto a region of the photocathode and wherein the adjustment mechanism comprises an actuator operable to change the position and/or the orientation of the mirror.

9. The electron injector of claim 6 , wherein the adjustment mechanism is operable to control the shape of the region of the photocathode which is illuminated by the radiation beam.

10. The electron injector of claim 9 , wherein the adjustment mechanism is operable to control the shape of the region of the photocathode which is illuminated by the radiation beam such that the beam of electrons emitted from the illuminated region takes on one or more desired properties after the steering unit applies a force to the beam of electrons.

11. The electron injector of claim 1 , wherein the adjustment mechanism comprises an actuator operable to change the position and/or the orientation of the photocathode.

12. The electron injector of claim 11 , wherein the actuator is operable to rotate the photocathode.

13. The electron injector of claim 1 , further comprising a controller wherein the controller is operable to control the adjustment mechanism in order to control the change of the region of the photocathode which is illuminated by the radiation beam.

14. The electron injector of claim 1 , wherein the steering unit is operable to adjust the force which is applied to the beam of electrons in response to the region of the photocathode which is illuminated by the radiation beam.

15. The electron injector of claim 13 , wherein the controller controls the adjustment of the force which is applied to the beam of electrons in response to the change of the region of the photocathode which is illuminated by the radiation beam.

16. The electron injector of claim 1 , further comprising an electron beam measurement device operable to measure one or more properties of the beam of electrons.

17. The electron injector of claim 16 , wherein the steering unit is operable to adjust the force which is applied to the beam of electrons in response to the measurement of one or more properties of the beam of electrons.

18. The electron injector of claim 1 , wherein the radiation source is a laser and the beam of radiation is a laser beam.

19. The electron injector of claim 18 , wherein the laser is a picosecond laser.

20. The electron injector of claim 1 , wherein the beam of electrons comprises a plurality of bunches of electrons.

21. The electron injector of claim 1 , wherein the electron injector further comprises an electron booster operable to accelerate the beam of electrons.

22. The electron injector of claim 1 , wherein the axis represents a desired trajectory of the beam of electrons which is output from the electron injector.

23. The electron injector of claim 1 , wherein the support structure is housed in an electron gun and wherein the electron injector further comprises an actuator operable to adjust the position and/or the orientation of the electron gun.

24. The electron injector of claim 23 , wherein the actuator is operable to adjust the position and/or the orientation of the electron gun in response to the change in the region of the photocathode which is illuminated by the radiation beam.

25. A free electron laser comprising:
an electron injector comprising:
a support structure arranged to support a photocathode;
a beam delivery system arranged to direct a beam of radiation from a radiation source onto a region of the photocathode thereby causing the photocathode to emit a beam of electrons;
an adjustment mechanism operable to change the region of the photocathode which is illuminated by the radiation beam; and
a steering unit operable to apply a force to the beam of electrons to alter its trajectory such that the electrons become substantially coincident with an axis of the electron injector;

a particle accelerator operable to accelerate the beam of electrons to relativistic speeds; and
an undulator operable to cause the relativistic electrons to follow an oscillating path thereby causing them to stimulate emission of coherent radiation.

26. The free electron laser of claim 25 , wherein the undulator is configured to cause the relativistic electrons to emit EUV radiation.

27. The free electron laser of claim 25 , wherein the particle accelerator is a linear accelerator.

28. The free electron laser of claim 27 , wherein the linear accelerator is an energy recovery linear accelerator, and wherein the free electron laser further comprises a merging unit configured to combine the electron beam output from the electron injector with a recirculating electron beam.

29. A method of producing an electron beam using an electron injector, the method comprising:
directing a beam of radiation onto a region of a photocathode thereby causing the photocathode to emit a beam of electrons;
changing the region of the photocathode which is illuminated by the radiation beam; and
applying a force to the beam of electrons to alter its trajectory such that the electrons become substantially coincident with an axis of the electron injector.

30. The method of claim 29 , wherein the applying a force to the beam of electrons comprises using one or more electromagnets to generate a magnetic field so as to alter the trajectory of the beam of electrons.

31. The method of claim 29 , wherein the region of the photocathode which is illuminated by the radiation beam is separated from the axis of the electron injector.

32. The method of claim 29 , wherein changing the region of the photocathode which is illuminated by the radiation beam comprises

Assignees

• Asml Netherlands Bv

Inventors

• Nikipelov Andrey Alexandrovich
• Banine Vadim Yevgenyevich
• De Jager Pieter Willem Herman
• De Vries Gosse Charles
• Frijns Olav Waldemar Vladimir
• Grimminck Leonardus Adrianus Gerardus
• Katalenic Andelko
• Akkermans Johannes Antonius Gerardus
• Loopstra Erik
• Engelen Wouter Joep
• Bartraij Petrus Rutgerus
• Coenen Teis Johan
• Op'T Root Wilhelmus Patrick Elisabeth Maria

Classifications

• H05H2007/084

  Electron sources · CPC title

• H05H7/08

  Arrangements for injecting particles into orbits · CPC title

• H01J1/34

  Photo-emissive cathodes (H01J1/35 takes precedence) · CPC title

• H01S3/0903 Primary

  Free-electron laser · CPC title