An Inverse Compton Scattering Radiation Source via Self-Guiding in a Plasma

In an inverse-Compton scattering source, in which a relativistic electron beam collides with a high-power laser pulse, the x-ray flux produced is proportional to the brightness of the two beams and the size of their overlap region in three-dimensional space. In vacuum, this overlap is limited by the diffraction of the two beams, but the diffraction limit can be overcome by confining both beams in a plasma guiding channel. A dense, bunched electron beam injected into an underdense plasma will self-guide via ``blowout,'' in which the beam head creates a focusing ion channel through which the body of the beam is guided; this same channel can also guides a counterpropagating laser beam. Constraints include the need for long laser wavelength (1 to 10 μm) and high beam densities. We present a possible configuration for a gamma-ray source using 180° Compton scattering in a uniform plasma, including 2D simulation results. Estimated photon yields are up to a factor of 5 larger than in vacuum scattering, with production of nearly 10 photons per nanocoulomb of electron beam charge.