Plasma accelerator

1. A method of accelerating charged particles in a plasma, the method comprising the steps of:

creating a region of non-uniform electric field within the plasma which propagates through the plasma;

using the non-uniform electric field to accelerate a first plurality of charged particles in the direction of propagation of the region of non-uniform electric field;

once the accelerating first plurality of charged particles have propagated part-way through the plasma:

(A) adding a second plurality of charged particles to the plasma, such that:

(i) the second plurality of charged particles propagates through the plasma with the accelerating first plurality of charged particles,

(ii) the second plurality of charged particles creates a local distortion in the non-uniform electric field experienced by the accelerating first plurality of charged particles, and

(iii) the local distortion in the non-uniform electric field propagates through the plasma with the accelerating first plurality of charged particles; and

(B) using the local distortion in the non-uniform electric field to accelerate the first plurality of charged particles in the direction of propagation of the region of non-uniform electric field.

2. The method of claim 1 , wherein the energy distribution of the first plurality of charged particles broadened due to the non-uniform electric field, and the energy distribution of the first plurality of charged particles is at least partially narrowed due to the local distortion in the non-uniform electric field.

3. The method of claim 1 , wherein the energy distribution of the first plurality of charged particles due to the non-uniform electric field and due to the local distortion in the electric field is equal or within a threshold amount.

4. The method of claim 1 , wherein at least one of the first or the second plurality of charged particles comprise a group, bunch, collection, packet, or beam of charged particles.

5. The method of claim 1 , wherein at least one of the first or the second plurality of charged particles comprise at least one of electrons, positrons, protons, or ions.

6. The method of claim 1 , wherein the non-uniform electric field is created by the propagation of a plasma wave through the plasma.

7. The method of claim 6 , wherein the plasma wave is created by a laser beam or particle beam interacting with the plasma.

8. The method of claim 1 , wherein the plasma comprises a low ionization threshold component and a high ionization threshold component.

9. The method of claim 8 , wherein the plasma wave propagates in the low ionization threshold component.

10. The method of claim 1 , wherein the first plurality of charged particles are created by the under-dense photocathode Trojan Horse method.

11. The method of claim 8 , wherein the second plurality of charged particles are electrons ionized from the high ionization threshold component.

12. A plasma accelerator configured to implement the method of claim 1 , the plasma accelerator comprising:

a plasma generator;

a first excitation source configured to create the non-uniform electric field which propagates through the plasma and which accelerates the first plurality of charged particles in the direction of propagation of the region of non-uniform electric field or, is configured to create the first plurality of charged particles within the plasma;

a second excitation source configured to create the second plurality of charged particles within the plasma once the first plurality of charged particles have propagated part-way through the plasma, wherein the second plurality of charged particles propagate through the plasma with the accelerating first plurality of charged particles, create the local distortion in the non-uniform electric field experienced by the accelerating first plurality of charged particles, the local distortion in the non-uniform electric field configured to accelerate the first plurality of charged particles in the direction of propagation of the region of non-uniform electric field; and

an external controller configured to control when at least one of the first or the second excitation sources interact with the plasma.

13. The plasma accelerator of claim 12 , wherein at least one of the first or the second excitation sources comprise at least one laser.

14. The plasma accelerator of claim 12 , wherein the plasma generator comprises a heater or an electromagnetic field generator.

15. The plasma accelerator of claim 12 , comprising at least one of:

a first transport system, configured to transport at least one of the first plurality of charged particles or the first excitation source into the plasma; or

a second transport system, configured to collect the first plurality of charged particles from the plasma.

16. An electromagnetic radiation source comprising the plasma accelerator of claim 12 .

17. The electromagnetic radiation source of claim 16 , wherein the electromagnetic radiation source is one of:

a free-electron laser,

an inverse Compton scattering light source, or

an ion channel laser.

18. The electromagnetic radiation source of claim 17 , wherein the inverse Compton scattering light source or the ion channel laser operate within the plasma of the plasma accelerator.