TY - JOUR
T1 - Microwave beam broadening due to turbulent plasma density fluctuations within the limit of the Born approximation and beyond
AU - Köhn, A.
AU - Guidi, L.
AU - Holzhauer, E.
AU - Maj, O.
AU - Poli, E.
AU - Snicker, A.
AU - Weber, H.
PY - 2018/5/15
Y1 - 2018/5/15
N2 - 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.
AB - 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.
KW - density fluctuations
KW - electromagnetic waves
KW - electron cyclotron waves
KW - magnetized plasmas
KW - plasma turbulence
KW - scattering of electromagnetic radiation
KW - simulation
UR - http://www.scopus.com/inward/record.url?scp=85048443659&partnerID=8YFLogxK
U2 - 10.1088/1361-6587/aac000
DO - 10.1088/1361-6587/aac000
M3 - Article
AN - SCOPUS:85048443659
VL - 60
SP - 1
EP - 13
JO - Plasma Physics and Controlled Fusion
JF - Plasma Physics and Controlled Fusion
SN - 0741-3335
IS - 7
M1 - 075006
ER -