On nonlinear scattering of drift wave by toroidal Alfvén eigenmode in tokamak plasmas Liu Chen1,2,3, Zhiyong Qiu1,3,∗ and Fulvio Zonca1,31 Institute for Fusion Theory and Simulation, School of Physics, Zhejiang University, Hangzhou, China 2 Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, United States of America 3 Center for Nonlinear Plasma Science and C.R. ENEA Frascati, C.P. 65, 00044 Frascati, Italy E-mail: zqiu@zju.edu.cn Received 19 March 2023, revised 1 August 2023 Accepted for publication 21 August 2023 Published 7 September 2023Abstract:Using electron drift wave (eDW) as a paradigm model, we have investigated analytically direct wave–wave interactions between a test DW and ambient toroidal Alfvén eigenmodes (TAEs) in toroidal plasmas, and their effects on the stability of the eDW. The nonlinear effects enter via scatterings to short-wavelength electron Landau damped kinetic Alfvén waves (KAWs). Specifically, it is found that scatterings to upper-sideband KAW lead to stimulated absorption of eDW. Scatterings to the lower-sideband KAW, on the contrary, lead to its spontaneous emission. As a consequence, for typical parameters and fluctuation intensity, nonlinear scatterings by TAEs have negligible net effects on the eDW stability; in contrast to the ‘reverse’ process investigated in Chen et al (2022 Nucl. Fusion 62 094001), where it is shown that nonlinear scattering by ambient eDWs may lead to significant damping of TAE.Keywords: toroidal Alfvén eigenmode, burning plasma, drift wave, nonlinear mode coupling, gyrokinetic theory (Some figures may appear in colour only in the online journal)
