Field compressing magnetothermal instability in laser plasmas.

Abstract

The mechanism for a new instability in magnetized plasmas is presented and a dispersion relation derived. Unstable behavior is shown to result purely from transport processes—feedback between the Nernst effect and the Righi-Leduc heat-flow phenomena in particular—neither hydrodynamic motion nor density gradients are required. Calculations based on a recent nanosecond laser gas-jet experiment [ D. H. Froula et al. Phys. Rev. Lett. 98 135001 (2007)] predict growth of magnetic field and temperature perturbations with typical wavelengths of order 50  μm and characteristic growth times of ∼0.1  ns. The instability yields propagating magnetothermal waves whose direction depends on the magnitude of the Hall parameter.