TOROIDAL ROTATION AND ION HEATING DURING NEUTRAL BEAM INJECTION IN PBX-M

Determination of the profiles of the ion temperature and the plasma toroidal rotation has been accomplished by charge exchange recombination spectroscopy in PBX-M. The angular momentum and the thermal ion energy transport have been studied mainly during the H mode phase of a high beta(p) discharge (I(p) approximately 330 kA, 3.5 x 10(19) less-than-or-equal-to n(e)BAR less-than-or-equal-to 6.5 x 10(19) m-3) having different heating beam configurations (combination of two perpendicular and two tangential neutral beam injections, abbreviated as 2 perp. NBI and 2 parall. NBI). The toroidal rotation velocity V(phi) rises substantially in the region of r/a greater-than-or-equal-to 0.5 after the L-H transition, and the V(phi) profile (peakedness) is more highly dependent on the beam configuration than the T(i) profile. The angular momentum confinement time varies from 147 ms (rigid rotation for 2 perp. NBI) to 39 ms (viscous rotation for 2 parall. NBI). In contrast, the thermal energy confinement time is 44-48 ms and is almost independent of the configuration. The transport analysis shows that the radial angular momentum diffusion is caused mainly by the viscous losses and that the angular momentum diffusivity chi(phi) is reduced substantially in the outer minor radius region during the 2 perp. NBI H mode. The neoclassical friction effect between the bulk ions and the impurities may influence the chi(phi) profiles locally, where the ion temperature gradient is steep. For all cases, the corrected chi(phi) profiles become similar to the profiles of the thermal energy diffusivity chi(eff) rather than the profiles of the ion energy diffusivity chi(i). For 2 perp. NBI, chi(phi) is smaller than chi(eff) over the outer minor radius of the plasma (r/a greater-than-or-equal-to 1/2), and for 2 parall. NBI, chi(phi) approximately 1.5 chi(eff). The results for the chi(phi) profiles are quantitatively consistent with the variation of the momentum confinement times.