Ion-Weibel filament dynamics in counter-streaming laser-driven plasma*

Simulations have shown that laser-driven, counter-streaming plasmas are susceptible to filamentation due to the nonlinear Ion-Weibel instability [1]. Experiments conducted on the OMEGA laser facility leveraged novel optical Thomson scattering techniques to measure these filaments and their associated B-fields by examining local intensity fluctuations in ion acoustic waves [2]. This project incorporates analysis of the electron plasma wave (EPW) measurements. The EPW data shows rapid fluctuations in plasma density. By measuring the density fluctuations, we can infer the size and growth rate of the filaments. This can then be compared to simulations that predict filament size and growth rate. Density gradients also point to the presence of magnetic pressure, and so can also be used to infer magnetic field strength. Additionally, we measure the ion and electron temperatures, and will compare them to collisional heating models in order to estimate the rate of heating due to the instability.

[1] C. Bruulsema , W. Rozmus , G. F. Swadling , S. Glenzer , H. S. Park, J.S. Ross, F. Fiuza , Phys. Plasmas 27 , 052104 (2020)

[2] G.F. Swadling, C. Bruulsema , F. Fiuza , D. P. Higginson, C.M. Huntington, H S. Park, B. B. Pollock, W. Rozmus , H. G. Rinderknecht , J. Katz, A. Birkel and J. S. Ross, Phys. Rev. Let. 124 , 215001 (2020)