Magnetic fluctuations in the range of ion cyclotron frequency in ULQ and RFP plasmas

Magnetic fluctuations in the range of the ion cyclotron frequency ( omega ci) are excited in the start-up and relaxation phases of ULQ and RFP plasmas. The fluctuations have high coherence in the omega ci range, 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 current), while the perpendicular component is in the direction of the ion diamagnetic drift. These fluctuations are considered to be excited by the micro-instability of ion cyclotron waves induced by fast electrons.