Formation of counter-streaming plasma flow inside solid target
The movie shows the temporal evolution of the magnetic fields when a 140 fs laser pulse with focused intensity (I = 10¹⁶ W/cm²) hits on solid target (n_e ~ 10²² cm⁻³). As the laser hits the target it generates fast electrons. In the beginning of the simulation, we initialised a warm background plasma electron isotropic temperature distribution. The background plasma ions form an immobile cold fluid background. The laser-plasma interaction then introduces an anisotropy in the electron temperature distribution. This anisotropy causes the growth of the Weibel instability, which consists in the formation of several electron current filaments that lead to the magnetic field structures shown in the movie. At the end of the movie, we can also observe the saturation of the Weibel instability, as the magnetic fields amplitudes stop growing exponentially. The Weibel instability is thought to play a critical role in extreme astrophysical scenarios. Our work shows that it is possible to mimic these conditions in the laboratory today.