Observation of Betatron X-Ray Radiation in a Self-Modulated Laser Wakefield Accelerator Driven with Picosecond Laser Pulses

Author(s): Albert, F; Lemos, N; Shaw, JL; Pollock, BB; Goyon, C; Schumaker, W; Saunders, AM; Marsh, KA; Pak, A; Ralph, JE; Martins, JL; Amorim, LD; Falcone, RW; Glenzer, SH; Moody, JD; Joshi, C | Abstract: © 2017 American Physical Society. American Physical Society. We investigate a new regime for betatron x-ray emission that utilizes kilojoule-class picosecond lasers to drive wakes in plasmas. When such laser pulses with intensities of ∼5×1018 W/cm2are focused into plasmas with electron densities of ∼1×1019 cm-3, they undergo self-modulation and channeling, which accelerates electrons up to 200 MeV energies and causes those electrons to emit x rays. The measured x-ray spectra are fit with a synchrotron spectrum with a critical energy of 10-20 keV, and 2D particle-in-cell simulations were used to model the acceleration and radiation of the electrons in our experimental conditions.