Bragg scattering induced laser deflection and electron injection in x-ray laser driven wakefield acceleration in crystals

Propagation of intense ultrashort x-ray laser pulse in a metal crystal and its effects on x-ray laser-driven wakefield acceleration are theoretically and numerically investigated with particle-in-cell simulations, where the bound electron effects are included. New features of laser pulse dissipation due to Bragg scattering have been observed and analyzed. The beat wave generated by the drive laser and scattered laser results in plasma density modulation and subsequent drive laser deflection. Continuous electron injection into the wakefields is also found due to the beat wave. These new features of laser propagation, wake generation, and electron injection provide effective controls on x-ray laser driven wakefield acceleration, where an acceleration gradient as high as 0.75 TV/cm is numerically demonstrated.