Pfc/ja-83-13 Parametric Phenomena in Electron Cyclotron Resonance Heating of Tokamak Plasmas

A theoretical study of parametric processes near the electron cyclotron resonance region in tokamak plasmas is presented. Parametric dispersion relations, including finite wave length of the driver pump, of principal and harmonic parametric excitations, are given. The problem of primary and secondary decays including their temporal and spatial growth rates is studied. In the nonlinear phase of development of the excited waves, a cascading saturation mechanism is invoked for both convective and absolute instabilities. Anomalous absorption frequencies and anomalous absorption lengths are evaluated for a variety of parametric excitations. Finally, a comparison between linear and nonlinear absorption processes is given. t Work supported by DOE Contract No. DE-AC02-78ET-51013. * Permanent address: "Boris KidrIc" Institute of Nuclear Sciences, Vinta, Beograd, Yugoslavia.