MEASUREMENTS OF BROAD-BAND FLUCTUATIONS AND PLASMA POTENTIAL WITH THE2 MEV HEAVY-ION BEAM PROBE ON THE TEXT-U TOKAMAK (ORAL)

Broadband density fluctuations and plasma potential profiles are measu red with a 2 MeV heavy ion beam probe (HIBP) diagnostic system on the TEXT-U tokamak. Measurements are performed in various locations includ ing the edge and the core, as well as the high and low field side regi ons of the plasma. Results show a poloidal asymmetry in the core densi ty fluctuation power spectra in which a distinct mode in the frequency range 70-170 kHz is present in the low field side region only. Furthe rmore, the HIBP provides a direct measurement of the local plasma pote ntial from which the electric field profile across the plasma is infer red. Results showing the poloidal asymmetry as well as the potential a nd electric field profiles are presented. (C) 1997 Elsevier Science S. A.