Kinetic effects in low-temperature plasmas

Abstract:

Some of the most important and fascinating phenomena in plasmas are related to kinetic effects, like e.g. collisionless heating or transport phenomena. Naturally, the distribution functions of the charged particles are at the heart of the problem. The distribution function is a result of the complex interaction of the particles with the gas atoms/molecules and the electric field structure. 

On the other hand, the electric field structure itself is usually resulting from the coupling to the electrons. Further, in low-temperature plasmas, the non-equilibrium conditions in these systems lead in general to distribution functions which deviate significantly from the standard Maxwellian distribution. 

While the common way of addressing kinetic effects is based on the use of the Boltzmann equation, an alternative approach for describing local Ohmic and non-local (stochastic) heating is provided by the Fokker-Planck equation supplemented by the Langevin equation. One advantage of this approach, as compared to the Boltzmann equation, is probably a more natural insight into the physics. 

Local and non-local interactions of electrons with fields are illustrated by selected examples. This includes the problem of self-consistent field structures, global distribution functions as well as tailored periodic field structures. Last not least, it will be shown that non-local effects can be important even under conditions of high collisionality. Finally, an outlook for further work on kinetic effects will be provided.