Design of Experiments to Study Relativistically Transparent Magnetic Filaments Using OMEGA EP

In relativistically transparent interactions, intense lasers can drive relativistic currents and azimuthal magnetic filaments in classically overdense plasmas. Simulations and theoretical models predict these relativistically transparent magnetic filaments can produce beams of high-energy photons. We designed experiments to study the efficiency of electron acceleration and x-ray production in near-critical-density foam-filled microchannel targets when driven by the OMEGA EP laser. Using analytical scaling laws supported by 3-D particle-in-cell simulations, we optimized the laser and target design parameters for maximum photon energy and efficiency. By varying the density of the target, the characteristic energy and number of radiated photons can be controlled. We also fine-tuned diagnostic systems to experimentally test the predicted characteristics of these electron and photon beams. We will present initial designs for gas-filled microchannel targets developed to achieve near-critical-density targets.