Laser Backscatter and Propagation in Magnetized Low-Density SiO₂ Foams

Self-generated and externally imposed magnetic fields can have significant impact on the dynamics of laser-driven plasma systems. We report on experiments that examine the effects of an externally applied external magnetic field on laser heat front propagation through sub-critical-density aerogels. Both pulsed-power-driven and laser-driven coils were used to impose external magnetic fields up to ~25 T. The plasma conditions were diagnosed using an imaging x-ray spectrometer, self-emission x-ray imaging, and backscatter diagnostics. Significantly more uniform laser energy deposition and differences in the observed backscattered Stimulated Brillioun Scattering spectrum are observed in the presence of external magnetic fields. These dynamics are consistent between either method of imposing an external magnetic field suggesting that laser-driven coils are a good candidate for use in generating magnetic fields for magnetized plasma studies. The results will be presented with a comparison to HYDRA simulations that explore the importance of various MHD terms in replicating the experimental results.