Effects of relativistic electrons on the calculated collective Thomson scattered spectra.

Abstract

The effects of relativistic electrons on the spectral density function S(k,\ensuremath{\omega}) are evaluated in the collective Thomson scattering regime for ion diagnostics. An electromagnetic code that calculates the electron density fluctuation term of S(k,\ensuremath{\omega}) has been modified by treating the electrons with a relativistic Maxwellian susceptibility tensor. Results are presented for calculated scattered spectra representative of the International Thermonuclear Engineering Reactor plasma parameters. Minor effects of relativistic electrons can be seen in the S(k,\ensuremath{\omega}) spectra only in scattering regimes where plasma resonances are present. Relativistic effects in S(k,\ensuremath{\omega}) are negligible in other scattering regimes where plasma resonances are not observable in the spectra. Relativistic effects are more dramatic at higher fluctuation frequencies (\ensuremath{\sim}100 GHz), where the electron Bernstein resonances and electron plasma frequency resonances can be observed. Significant broadening of Bernstein resonance features toward lower frequencies and overlapping of resonance harmonic features at high electron temperatures were noted in the calculated scattered spectra.