Far-infrared laser interferometry measurements on the STP-3(M) reversed-field pinch

摘要

Far-infrared laser interferometry at 432 (mu)m was carried out on the STP-3(M) reversed-field pinch. Measurements along two vertical chords showed a change from a parabolic-like to a flat-like electron density profile after field reversal. A density profile inversion and a correlated toroidal magnetic flux perturbation were also observed during the transition from the current rising to the current decay phase. Measurements of electron density fluctuations indicated relative fluctuation levels of (approx)10% for both chords during the current rising phase and (approx)5% and (approx)15% during the current decay phase for the central and outer chords, respectively. Spectral analysis showed a (approx)30 kHz mode consistent with poloidal mode number m=0 magnetic fluctuations, and a (approx)90 kHz mode localized to the outer region of the plasma, which was strongly excited during the current decay phase and may be connected to particle and energy transport in STP-3(M). (author). (ERA citation 19:020420)