Particle-in-Cell simulations of the current filamentation instability in laser produced solid density plasmas

The propagation of high-energy charged particles in plasmas can produce growing electromagnetic fields via the current filamentation instability. This phenomena plays an important role in the self-magnetization of many astrophysical and laboratory environments such as young supernova remnant shocks and gamma-ray bursts. Over the past decades, there has been a continuing effort to study the current filamentation instability in controlled laboratory experiments using both particle beams and laser-driven systems. Its experimental characterization in solid density plasmas poses however significant challenges to conventional diagnostics using particle beams or optical probing. Here, we present theoretical and simulation results supporting new experiments performed at SLAC, where the LCLS X-ray free electron laser was used together with the MEC high intensity laser to image for the first time solid density laser-plasma interactions in a pump-probe configuration. We find that the the filaments linear properties and non-linear evolution are strongly modified by effects such as resistivity, ion dynamics, and the coupling with electrostatic modes. Those results, together with the experimental X-ray imaging of the filaments, will stimulate the development of improved theoretical models for the filamentation instability in solid density plasmas.