Evolution of filaments and associated magnetic fields produced by the Weibel Instability in two counterstreaming laser plasmas

The evolution of filaments due to the Weibel Instability was studied through experiments of two asymmetric counterstreaming plasmas produced by nanosecond laser pulses with total energy more than 1 kJ. The magnetic field around filaments was measured by the Faraday rotation technique as tens of Tesla after an exponential growth at the rate of 0.148 ns - 1, which was in good agreement with the calculated features of the Weibel Instability with experimental plasma properties. The temporal evolution of the separation distances between filaments was also recorded and fitted with two analytical models by Medvedev et al. [Astrophys. J. 618, L75-L78 (2005)] and Ruyer et al. [Phys. Plasmas 22, 032102 (2015)], respectively. While the magnetic field growth followed the quasi-linear theory of the Weibel Instability process in counterstreaming plasmas of non-relativity, the evolution of filaments through coalescence behaviors presented a nonlinear temporal increase in the filament widths.