Vlasov-Fokker-Planck simulations of pre-magnetized ablating planar targets

Abstract

Magnetic fields, spontaneously generated around laser heating nonuniformities, have been found to invert and enhance electron pressure perturbations in the conduction zones of laser-produced plasmas without applied magnetic fields. The application of a sufficiently strong magnetic field is predicted to damp this phenomenon, but may instead result in magneto-thermal instability. Two-dimensional Vlasov-Fokker-Planck simulations of the conduction zone of laser-produced plasmas, subject to externally applied magnetic fields of different field strengths, are performed. The effects of non-locality upon extended collisional transport terms and instability thresholds are investigated. It is found that magnetized transport terms Righi-Leduc heat flow and thermoelectric heat flow are strongly enhanced by non-locality (up to twofold), even at the top of the temperature gradient, due to larger magnetization of the mediating hot electrons (relative to their thermal counterparts). Meanwhile, the Nernst effect efficiently advects magnetic field out of the conduction zone before instability (which requires Hall parameters, χ>0.1) can take hold.