Measurements of broadband fluctuations and plasma potential with the 2 MeV heavy ion beam probe on the TEXT-U tokamak (oral)

Broadband density fluctuations and plasma potential profiles are measured with a 2 MeV heavy ion beam probe (HIBP) diagnostic system on the TEXT-U tokamak. Measurements are performed in various locations including the edge and the core, as well as the high and low field side regions of the plasma. Results show a poloidal asymmetry in the core density fluctuation power spectra in which a distinct mode in the frequency range 70-170 kHz is present in the low field side region only. Furthermore, the HIBP provides a direct measurement of the local plasma potential from which the electric field profile across the plasma is inferred. Results showing the poloidal asymmetry as well as the potential and electric field profiles are presented.