Measurements of microwave radiation from turbulently heated plasmas

Abstract

Intense microwave radiation from a turbulently heated plasma in a frequency range near the electron plasma frequency omega pe was observed and its relations with plasma resistance R were studied for two cases. When the plasma was highly resistive, (i) the power of microwave radiation at a frequency larger than omega pe was proportional to R2 in lower density region ( approximately 2.5*1013 cm-3), however (ii) the radiation power at a frequency smaller than Omega pe was proportional not to R2 but rather to R in higher density region ( approximately 6*1013 cm-3). The microwave radiation in the former case was emitted dominantly by non-linear coupling between waves in the plasma and the radiation in the latter case by linear conversion due to the density gradient.