A hybrid full-wave Markov chain approach to calculating radio-frequency wave scattering from scrape-off layer filaments
Name
2108.07077.pdf
Description
Submitted version
Size
8.02 MB
Format
Adobe PDF
Checksum (MD5)
4b3303c8df0f6efdfeda9f012bb34c7d
Author(s)
Biswas, Bodhi
Shiraiwa, Syun'ichi
Baek, Seung-Gyou
Bonoli, Paul
Ram, Abhay
White, Anne E
Date Issued
2021
Journal
Journal of Plasma Physics
Publisher
Cambridge University Press (CUP)
Citation
Biswas, Bodhi, Shiraiwa, Syun'ichi, Baek, Seung-Gyou, Bonoli, Paul, Ram, Abhay et al. 2021. "A hybrid full-wave Markov chain approach to calculating radio-frequency wave scattering from scrape-off layer filaments." Journal of Plasma Physics, 87 (5).
Version
Original manuscript
Abstract
The interaction of radio-frequency (RF) waves with edge turbulence modifies the incident wave spectrum, and can significantly affect RF heating and current drive in tokamaks. Previous lower hybrid (LH) scattering models have either used the weak-turbulence approximation, or treated more realistic, filamentary turbulence in the ray tracing limit. In this work, a new model is introduced which retains full-wave effects of RF scattering in filamentary turbulence. First, a Mie-scattering technique models the interaction of an incident wave with a single Gaussian filament. Next, an effective differential scattering width is derived for a statistical ensemble of filaments. Lastly, a Markov chain solves for the transmitted wave spectrum in slab geometry. This model is applied to LH launching for current drive. The resulting wave spectrum is asymmetrically broadened in angular wavenumber space. This asymmetry is not accounted for in previous LH scattering models. The modified wave spectrum is coupled to a ray tracing/Fokker–Planck solver (GENRAY/CQL3D) to study its impact on current drive. The resulting current profile is greatly altered, and there is significant increase in the on-axis current and decrease in the off-axis peaks. This is attributed to a portion of the modified wave spectrum that is strongly dampened on-axis during the first pass.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1017/S0022377821001033
