Microwave beam broadening due to turbulent plasma density fluctuations within the limit of the Born approximation and beyond. (15th May 2018)

• Record Type: Journal Article
• Authors: Köhn, A; Guidi, L; Holzhauer, E; Maj, O; Poli, E; Snicker, A; Weber, H
• Is Part Of: Plasma physics and controlled fusion. Volume 60:Number 7(2018:Jul.)
• Publication Date: 2018-05-15
• Subjects: magnetized plasmas -- electromagnetic waves -- plasma turbulence -- scattering of electromagnetic radiation -- electron cyclotron waves -- density fluctuations -- simulation; 47.11.Bc -- 52.25.Os -- 52.35.Hr -- 52.35.Ra -- 52.40.Db -- 52.70.Gw; Plasma (Ionized gases) -- Periodicals; Controlled fusion -- Periodicals; 530.44
• DOI: 10.1088/1361-6587/aac000
• Languages: English
• ISSNs: 0741-3335

Abstract

Abstract: Plasma turbulence, and edge density fluctuations in particular, can under certain conditions broaden the cross-section of injected microwave beams significantly. This can be a severe problem for applications relying on well-localized deposition of the microwave power, like the control of MHD instabilities. Here we investigate this broadening mechanism as a function of fluctuation level, background density and propagation length in a fusion-relevant scenario using two numerical codes, the full-wave code IPF-FDMC and the novel wave kinetic equation solver WKBeam. The latter treats the effects of fluctuations using a statistical approach, based on an iterative solution of the scattering problem (Born approximation). The full-wave simulations are used to benchmark this approach. The Born approximation is shown to be valid over a large parameter range, including ITER-relevant scenarios.