Spectral broadening from turbulence in multiscale lower hybrid current drive simulations

Nuclear Fushion

article

Bodhi Biswas¹  Paul Bonoli¹  Abhay Ram¹  Anne White¹ 

[1] Plasma Science and Fusion Center, Massachusetts Institute of Technology

关键词: LHCD;    filament;    Alcator C-Mod;    turbulence;   

DOI  :  10.1088/1741-4326/aca6fb

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

The scattering of lower hybrid (LH) waves due to scrape-off layer filaments is investigated. It is revealed that scattering can account for the LH spectral gap without any ad hoc modification to the wave-spectrum. This is shown using a multiscale simulation approach which allows, for the first time, the inclusion of full-wave scattering physics in ray-tracing/Fokker–Planck calculations. In this approach, full-wave scattering probabilities are calculated for a wave interacting with a statistical ensemble of filaments. These probabilities are coupled to ray-tracing equations using radiative transfer theory. This allows the modeling of scattering along the entire ray-trajectory, which can be important in the multi-pass regime. Simulations are conducted for LH current drive (LHCD) in Alcator C-Mod, resulting in excellent agreement with experimental current and hard x-ray profiles. A region in filament parameter space is identified in which the impact of scattering on LHCD is saturated. Such a state coincides with experimental LHCD measurements, suggesting saturation indeed occurs in C-Mod, and therefore the exact statistical properties of the filaments are not important.

【 授权许可】

Unknown