Temperature separation under compression of moderately-coupled plasma

Abstract

In moderately-coupled plasmas, a significant fraction of the internal energy resides in electric fields. As these plasmas are heated or compressed, the shifting partition of energy between particles and fields leads to surprising effects, particularly when ions and electrons have different temperatures. In this work, quasi-equations of state (quasi-EOS) are derived for two-temperature moderately-coupled plasma in a thermodynamic framework and expressed in a simple form. These quasi-EOS readily yield expressions for correlation heating, in which heating of the electrons causes a rapid increase in ion temperature even in the absence of collisional energy exchange between species. It is also shown that, remarkably, compression of moderately-coupled plasma drives a temperature difference between electrons and ions, even when the species start at equal temperature. These additional channels for ion heating may be relevant in designing ignition schemes for inertial confinement fusion (ICF).