MAGNETIC FLUCTUATIONS IN THE RANGE OF ION-CYCLOTRON FREQUENCY IN ULQ AND RFP PLASMAS

Magnetic fluctuations in the range of the ion cyclotron frequency (ome ga(ci)) are excited in the start-up and relaxation phases of ULQ and R FP plasmas. The fluctuations have high coherence in the omega(ci) rang e, and have the wavenumber vector k directed almost perpendicular with respect to the ambient magnetic field. The parallel component of k is in the direction of the electron drift (opposite to the plasma curren t), while the perpendicular component is in the direction of the ion d iamagnetic drift. These fluctuations are considered to be excited by t he micro-instability of ion cyclotron waves induced by fast electrons.