Changes to the ion temperature profile during IBW heating in PBX-M

The introduction of Ion Bernstein Wave Heating (IBWH) experiments in PBX-M have demonstrated significant bulk ion heating and ion temperature (Ti) profile modification. Ti profiles were obtained using a multi-channel, charge-exchange recombination spectroscopy system (the CHERS diagnostic). With IBWH, there are density increases; so to produce comparative discharges when no IBWH is present, additional gas must be injected. For bar ne, of ∼3x1013 cm-3, the central ion temperature, Ti0, was observed to increase by 350 eV when 0.6 MW of IBWH was applied for ∼300 msec. The product bar ne Ti0, a measure of the ion stored energy, increases linearly with IBWH power. The Ti profile broadened with IBWH and the ion temperature gradient steepened near the predicted power deposition layer, providing evidence of localized heating. Examination of ΔTi profile evolution indicated that the IBWH power was, in fact, deposited in a localized, off-axis region