Microwave beam broadening due to turbulent plasma density fluctuations within the limit of the Born approximation and beyond

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.

Keywords

density fluctuations, electromagnetic waves, electron cyclotron waves, magnetized plasmas, plasma turbulence, scattering of electromagnetic radiation, simulation

DOI

10.1088/1361-6587/aac000

Citation

Köhn , A , Guidi , L , Holzhauer , E , Maj , O , Poli , E , Snicker , A & Weber , H 2018 , ' Microwave beam broadening due to turbulent plasma density fluctuations within the limit of the Born approximation and beyond ' , Plasma Physics and Controlled Fusion , vol. 60 , no. 7 , 075006 , pp. 1-13 . https://doi.org/10.1088/1361-6587/aac000

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-201808014359

Collections

[article-cris] Perustieteiden korkeakoulu / SCI

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