Nonlinear mode conversion and anomalous absorption processes during radio-frequency heating of bumpy torus plasmas

The theory of nonlinear mode conversion is reviewed and applied to the ELMO Bumpy Torus (EBT) [Proceedings of the 5th International Conference on Plasma Physics and Controlled Nuclear Fusion Research 1974 (IAEA, Vienna, 1975), Vol. 2, p. 141] environment in the electron-cyclotron, upper-hybrid, lower-hybrid, and ion-cyclotron frequency ranges. A variety of parametric excitations in these frequency ranges is studied. Based on cascade saturation mechanisms, the parametric turbulence levels and corresponding anomalous absorption rates of the excited modes are evaluated. The relevance of nonlinear mode conversion for contemporary and future EBT experiments is discussed.