High time resolution ion temperature profile measurements on PBX

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Abstract
Ion temperature profiles with a time resolution of 2–5 ms have been measured on the Princeton Beta Experiment tokamak (PBX) by charge-exchange recombination spectroscopy (CXRS) and a neutral particle charge-exchange analyzer (NPA). The sightlines of both diagnostics crossed the trajectory of a near-perpendicular heating beam, which enhanced the local neutral density (∝ signal strength) and provided spatial resolution. The time resolution of these two independent techniques is sufficient to see sawtooth oscillations and other magneto- hydrodynamic activity. Effects of these phenomena on the toroidal rotation velocity profile, vφ(r), are clearly observed by CXRS. For example, a sharp drop in the central vφ occurs at the sawtooth crash, followed by a linear rise during the quiescent phase. The NPA results are compared with those from CXRS.