Electrostatic turbulence intermittency and MHD relaxation phenomena in a RFP plasma

The basic statistical features of the electrostatic fluctuations in the edg e plasma of the RFX reversed field pinch fusion device and their relationsh ip with magnetic relaxation events are reported. The analysis of time serie s of floating potential measurements obtained at low plasma current (< 400 kA) has shown a clear elation between low-frequency (f < 5 kHz) electrostat ic fluctuations and reversal parameter F fluctuations elated to relaxation events. The electrostatic turbulence measurements have been investigated th rough the wavelet decomposition technique, and intermittent structures have been identified. These structures are found to occur mainly during relaxat ion events. The probability distribution function of waiting times between intermittent structures shows a power law trend, which is a clear evidence of memory-characterized phenomena.