UC San Diego

In this dissertation a systematic study of transport by super-thermal electrons in matter, using the kinetic theory and numerical simulation, is presented. This work can be divided into three major parts. The first part studies the electron thermal transport in a semi- collisionless plasma, which is also known as nonlocal transport. It was found that the nonlocal transport can be well described using a hydrodynamic framework, improved by adding a new parameter describing the energy distribution tail. For the case of a strong B-field, the accurate description of the nonlocal electron heat flux can be achieved by using an integral expression for the heat flux derived from the approximate solution of the kinetic equation. The second and third parts of this work study the ionization wave induced by the intense electron beam propagating in different insulators. First, we study beam propagation in a solid insulator and find a non-monotonic ionization front velocity dependant on the beam density. This front velocity variation with the density can create instabilities seen in experiments. Second, we study the ionization wave in a gas induced by a dense beam. We find that, in agreement with experimental data, the ionization front velocity is much less then the beam electron velocity for low gas densities, and that the front velocity exponentially increases with the gas density