X-ray generation

1. An apparatus for extracting energy from a particle beam comprising:

a particle beam generator;

a first superconducting device arranged to apply an electric and/or magnetic field to accelerate the particle beam;

an arrangement configured to extract energy from the accelerated particle beam through an interaction process;

a second superconducting device arranged to apply an electric and/or magnetic field to decelerate the particle beam after it has interacted; and

a superconducting electromagnetic coupling arranged to recuperate energy from the particle beam as it passes through the second device and transfer the recuperated energy into the first device;

wherein the first and second devices are arranged substantially in parallel and side-by-side; and

wherein at least the first device, second device and superconducting coupling are provided together in a cryostat.

2. The apparatus of claim 1 , wherein the first and second superconducting devices comprises a plurality of RF cavities in which an RF electric field is applied to accelerate/decelerate the electron beam.

3. The apparatus of claim 1 , wherein the superconducting coupling arranged to recuperate energy from the particle beam comprises one or more waveguides that connect the first and second devices to transfer energy in the form of RF electromagnetic radiation.

4. The apparatus of claim 1 , wherein at least one of the particle beam generator or the arrangement configured to extract energy from the particle beam is provided in the cryostat.

5. The apparatus of claim 1 , wherein the particle beam comprises one or more of: electrons, positrons, protons, or ions.

6. The apparatus of claim 1 , wherein the first and second devices are arranged substantially in parallel or side-by-side.

7. The apparatus of claim 1 , wherein at least one of the first device or the second device is a linear accelerator.

8. The apparatus of claim 7 , wherein the first device and the second device each include an axis, and the axes are arranged substantially parallel to one another.

9. The apparatus of claim 1 , further comprising an arrangement configured to turn the beam substantially through 180° between the first device and the second device.

10. The apparatus of claim 9 , wherein a photon source is arranged to provide photons to interact with the electron beam as the accelerated beam turns through an angle of about 90° after passing out of the first device.

11. The apparatus of claim 1 , wherein:

the particle beam generator is an electron beam generator;

the particle beam is an electron beam;

the first superconducting device is arranged to apply an RF electric field to accelerate the electron beam from the generator;

the arrangement configured to extract energy from the accelerated article beam is a photon source arranged to provide photons to interact with the electron beam from the first device so as to generate x-rays via inverse-Compton scattering;

the second superconducting device is arranged to apply an RF electric field to decelerate the electron beam after it has interacted; and

wherein the first and second superconducting devices are connected by the superconducting electromagnetic coupling, which is an RF energy transmission coupling arranged to recover RF energy from the decelerated electron beam as it passes through the second device and transfer the recovered RF energy into the first device.

12. The apparatus of claim 11 , wherein the RF energy transmission coupling comprises one or more RF waveguides connecting the first and second devices.

13. The apparatus of claim 11 , wherein at least one of the first device or the second device comprises one or more RF cavities arranged in series.

14. The apparatus of claim 13 , wherein each RF cavity in the second device is coupled to a corresponding RF cavity in the first device by a respective waveguide.

15. The apparatus of claim 11 , wherein the first and second devices each have respective upstream and downstream ends, and wherein the downstream end of the second device is connected to the upstream end of the first device by the RF energy transmission coupling.

16. An apparatus for extracting energy from an electron beam comprising:

an electron beam generator;

a first device comprising a plurality of superconducting RF cavities in which an RF electric field is applied to accelerate the electron beam;

an arrangement configured to extract energy from the accelerated electron beam through an interaction process; and

a second device comprising a plurality of superconducting RF cavities in which an RF electric field is applied to decelerate the electron beam after it has interacted;

wherein the first and second devices are connected by one or more superconducting RF waveguide(s) arranged to recover RF energy from the decelerated electron beam as it passes through the second device and transfer the recovered RF energy into the first device;

wherein the first and second devices are arranged substantially in parallel and side-by-side; and

wherein the superconducting RF cavities of the first and second devices and the superconducting RF waveguide(s) are provided in the same cryostat.

17. The apparatus of claim 16 , wherein the interaction process comprises at least one of: interacting the electron beam with photons to generate x-rays via inverse-Compton scattering; passing the electron beam through an undulator or applying an alternating magnetic field to generate electromagnetic radiation; directing the electron beam onto a target to cause emission and/or fluorescence; or interacting the electron beam directly with a sample for electron diffractometry or microscopy.

18. The apparatus of claim 16 , wherein the superconducting RF cavities of the first and second devices and the superconducting RF waveguide(s) are integrally formed or connected together.

19. The apparatus of 16 , wherein the superconducting RF cavities of the first and second devices and the superconducting RF waveguide(s) are provided in the same cryostat.

20. A method for extracting energy from a particle beam comprising the steps of:

generating a particle beam;

passing the particle beam through a first superconducting device arranged to apply an electric and/or magnetic field to accelerate the particle beam;

extracting energy from the accelerated particle beam through an interaction process;

passing the particle beam through a second superconducting device arranged to apply an electric and/or magnetic field to decelerate the particle beam after it has interacted; and

arranging a superconducting coupling to recuperate energy from the particle beam as it passes through the second device and transfer the recuperated energy into the first device;

wherein the first and second devices are arranged substantially in parallel and side-by-side; and

wherein at least the first device, second device and superconducting coupling are provided together in a cryostat.

21. The method of claim 20 , wherein the particle beam includes one or more of electrons, positrons, protons, or ions.