On the Simplification of the Modeling of Electron-cyclotron Wave Propagation in Thermonuclear Fusion Plasmas

The launching of high-frequency electromagnetic waves into fusion plasmas is an effective method for plasma heating and noninductive current drive. In addition, the reflection of electromagnetic waves on the plasma cutoffs is utilized in electron density diagnostic measurements. The scope of this article is to comment on the standard approximations made in the simulation of electron-cyclotron wave propagation and absorption in tokamak plasmas, in connection to the established modeling tools and the underlying physics, as well as to illustrate the limits of their validity, especially regarding the applicability to ITER-related studies and beyond. The identification of possible gaps in the current state-of-the-art and the implication of new requirements for theory and modeling are also discussed.