Temperature and Density Measurements in Low-Density, Laser-Driven Magnetized Plasmas Using Thomson Scattering

We present electron temperature and density data from Thomson scattering measurements on recent collisionless shock experiments on the Trident laser at Los Alamos National Laboratory. A graphite or CH target was placed inside a static magnetic field ($\sim1$ kG) created by a $50$ cm-diameter Helmholtz coil and was ablated by two sequential laser pulses at $1053$ nm. The first pulse created an ambient low-density, magnetized plasma while the second pulse created a super-Alfv\'{e}nic (M$_{A}$ $\sim10$) plasma to shock the ambient plasma. A seperate laser beam at $527$ nm was used for Thomson scattering to characterize the ambient plasma $3 - 19$ cm radially from the target and $0.5 - 9.7$ $\mu$s after the first ablation. The electron temperature was found to be $10 - 50$ eV and, combined with Rayleigh scattering, the electron density was found to be $10^{13}- 10^{15}$ cm$^{-3}$. Several carbon emission lines were also observed in the Thomson spectrum and were compared to FLYCHK simulations to characterize the ambient plasma charge state.