Laser-plasma electron accelerator for all-optical inverse Compton X-ray source

Inverse Compton scattering has been gaining attention as a process for the generation of X/γ-ray, since it produces tunable X/γ-ray pulses with a small cone angle of radiation. A table-top tunable Compton X/γ-ray source would be realized by replacing a radio frequency (rf) linac with a laser wakefield accelerator (LWFA), which is one of the advanced accelerators. An empirical scaling law for the LWFA in the self-injection mode showed that the energy gain was inversely proportional to the plasma density. In order to effectively employ the LWFA as a Compton X/γ-ray source, its stability must be improved. For this purpose, we are developing techniques for the injection of initial electrons by a localized wavebreaking at the density ramp of a plasma. The pointing stability and acceleration efficiency of the electron beam were significantly improved by applying an axial magnetic field to the plasma channel.