FLUCTUATIONS AND TRANSPORT IN RFP EDGE PLASMA

Edge plasma fluctuations are studied with inserted triple Langmuir pro bes and magnetic coils in the TPE-1RM20 reversed-field pinch. Two-poin t measurements show that density and potential fluctuations have relat ively low mode numbers (m < 3, n < 40). High coherence (gamma = 0.5) w ith magnetic field fluctuations and similar mode spectra suggest that density and potential fluctuations are mainly caused by electromagneti c turbulence. Broadband magnetic fluctuations are dominated by m = 0, low-n modes and internally resonant m = 1 and m = 2 modes. A coherent (f = 20-30kHz) m = 0, low-n mode is also observed. Particle flux drive n by electrostatic electric field fluctuations is 50-100% of total flu x obtained from D-alpha line intensity measurement. Low-frequency fluc tuations (f < 100kHz) give the main contribution to the total flux. El ectrostatic fluctuation driven electron energy flux is only of the ord er of 10% of total non-radiative power loss.