Fluctuations in the Ion-Cyclotron-Frequency Range: Possible Measurement ofTeTiin Tokamaks

Abstract

The thermal density fluctuations in a typical tokamak plasma, for a wave vector perpendicular to the magnetic field and for a wavelength of the order of the ion gyroradius, are shown to be maximum at the frequency of the zero-group-velocity ion cyclotron waves. This frequency is sensitive to the ion- to electron-temperature ratio and the spectrum remains peaked despite a poor scattering-vector definition and destabilizing effects such as presence of a current. Possible applications to tokamak diagnosis are emphasized.