Mathematisch-Naturwissenschaftliche Fakultät

Institut für Physik

Fachgebiet: Theoretische Physik

Betreuer: PD Dr. Heidi Reinholz

B. Sc. John Adams
(e-mail: )

Magnetotransport Properties of Dense Plasmas

Linear response theory (LRT), developed within the Zubarev formalism, has previously been successfully applied to systems in an external electric field and containing a temperature gradient. In this work an extension of LRT is presented, allowing a description of systems in an external magnetic field. The well known expressions for the electrical and heat conductivities and the thermopower are modified to include magnetic field effects. Furthermore, expressions for the Hall, Nernst and Leduc-Righi coefficients are also derived. These are compared with expressions derived within the relaxation time approximation, in which electron-electron (e-e) interactions are neglected. New results are obtained in the low density limit within LRT, in which (e-e) interactions can be consistently included.

This work focuses on transport in noble gas plasmas, in particular the electrical conductivity and the Hall coefficient, for which recent measurements are available. For the electrical conductivity, excellent agreement between theory and experiment is achieved for the first time, by using experimental results for the electron-neutral (e-a) cross sections instead of a theoretical polarisation potential. The Ramsauer minimum observed in the e-a cross sections is then properly taken into account.

Finally, the possibility of using experimental measurements of the Hall coefficient as a diagnostic tool for determining the free electron density of a partially ionised plasma is discussed. While theoretical and experimental results for the Hall coefficient are in approximate agreement, there are large uncertainties involved. It is therefore suggested that further work is required in order to develop this method as an accurate diagnostic tool.