Parametric Decay Instabilities during Electron Cyclotron Resonance Heating of Fusion Plasmas, Problems and Possibilities
Hannes Weber, Omar Maj, Emanuele Poli
Abstract
A paraxial expansion of the (ensemble-averaged) Wigner function in the relevant wave kinetic equation for electron cyclotron waves in fluctuating plasmas allows the derivation of phase-space equations similar to the equations for the Gaussian beam parameters in the paraxial WKB method [G.V. Pereverzev, Phys. Plasmas 5 , 3529 (1998)]. This is relatively straightforward when the scattering of the wave field by density fluctuations can be described by a diffusion operator in refractive-index space. The general case is rather more complicated, yet we could find a heuristic construction of a paraxial Wigner function. Here we use a simple model, which has an analytical solution, to test both the theoretical validity of the diffusion approximation and the heuristic paraxial approach beyond the diffusion approximation.
BibTeX
@article{Weber_2023,
title={Paraxial beams in fluctuating fusion plasmas: Diffusive limit and beyond},
volume={277},
ISSN={2100-014X},
url={http://dx.doi.org/10.1051/epjconf/202327701003},
DOI={10.1051/epjconf/202327701003},
journal={EPJ Web of Conferences},
publisher={EDP Sciences},
author={Weber, Hannes and Maj, Omar and Poli, Emanuele},
editor={Poli, E. and Liu, Y. and Udintsev, V.},
year={2023},
pages={01003} }