Density profile modification during IBW in PBX‐M

Application of IBW power to neutral beam heated PBX‐M discharges was observed to progressively peak the electron density profile, inducing gradients in excess of 5×1012 cm−4 and central density up to 8×1013 cm−3. Abated MHD activity occurred during the peaking phase. Core ion thermal diffusivity dropped during the same period to values neighboring 1 m2/s. Induced large ne gradients were spatially correlated with the IBW deposition profile. Bootstrap current induced in mid minor radius region broadened the total current profile. Work supported by DOE contract no. DE‐AC02‐76‐CH0‐3073.