The deteriorating effect of plasma density fluctuations on microwave beam quality

¹ Institute of Interfacial Process Engineering and Plasma Technology, University of Stuttgart , Stuttgart Germany
² Max Planck Institute for Plasma Physics Garching Germany
³ Institute for Fusion Studies, University of Texas at Austin , TX USA
⁴ General Atomics PO Box 85608, San Diego CA USA
⁵ York Plasma Insitute, Department of Physics, University of York, York U.K
⁶ Department of Applied Physics, Aalto University , Aalto Finland

^* e-mail: koehn@igvp.uni-stuttgart.de

Published online: 25 March 2019

Abstract

Turbulent plasma edge density fluctuations can broaden a traversing microwave beam degrading its quality. This can be a problem for scenarios relying on a high spatial localization of the deposition of injected microwave power, like controlling MHD instabilities. Here we present numerical estimations of the scattering of a microwave beam by density fluctuations over a large parameter range, including extrapolations to ITER. Two codes are used, the full-wave code IPF-FDMC and the wave kinetic equation solver WKBeam. A successful comparison between beam broadening obtained from DIII-D experiments and corresponding full-wave simulations is shown.