Development of a small divergence, small source size and short pulse duration x-ray source is highly desirable for HEDS experiments. Many of the facilities where HEDS is studied have ps-pulse duration and kJ class lasers. We propose to use these laser pulses to create a x-ray source based on a self-modulated laser wakefield accelerator (SMLWFA). In this work we explore through experiments and PIC simulations the radiation generated in SMLWFA.
Development of a directional, small-divergence, small source size and short pulse duration x-ray source is highly desirable for high energy density science (HEDS) experiments. Since many of the facilities where HEDS is studied have ps-pulse duration and kJ-class lasers that can be overlapped in space and time to the long drive pulse, we propose to use the kJ ps laser pulses to create a betatron x-ray source based on a self-modulated laser wakefield accelerator. Due to its intrinsic directionality, small divergence and high-brightness this x-ray source would be and ideal probe and backlighter for facilities such as Omega_EP, Petal and NIF-ARC.
In this work we explore through experiments and PIC simulations the betatron radiation generated in self-modulated laser-wakefield accelerators. The experiment was preformed at the Jupiter Laser Facility, LLNL, by focusing the Titan short pulse beam (120 J, 1 ps) onto the edge of a 4 mm Helium gas jet. We used a long focal length optic, f#10, which produced a laser normalized vector potential, a0, of 2 and generated a plasma with an electronic density of 1019 cm-3. Electrons with energies up to 200 MeV and Betatron x-rays with critical energies around 10 keV were observed.
OSIRIS 2D PIC simulations indicate that the accelerated electrons gain energy both from the plasma wave and from direct laser acceleration. The post-processing code JRad  shows that the accelerated electrons produce radiation with energies exceeding 50keV and that it directly scales with the a0 of the laser .
 Martins J L, Martins S F, Fonseca R A and Silva L O 2009 Proc. SPIE 7359 73590V
 Lemos, N., Martins, J. L., Tsung, F. S., Shaw, J. L., Marsh, K. A., Albert, F., Pollock, B. B., et al. (2016). Self-modulated laser wakefield accelerators as x-ray sources. Plasma Phys. and Control. Fusion, 1–11. IOP Publishing. doi:10.1088/0741-3335/58/3/034018
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