Initial operation of the NSTX-Upgrade Real-Time Velocity diagnostic

Authors:  M. Podesta, R. E. Bell

Abstract:  A Real-Time Velocity (RTV) diagnostic based on active charge-exchange recombination spectroscopy is now operational on the National Spherical Torus Experiment-Upgrade (NSTX-U) spherical torus [J. E. Menard et al., Nucl. Fusion 52, 083015 (2012)]. The system has been designed to supply plasma velocity data in real time to the NSTX-U Plasma Control System, as required for the implementation of toroidal rotation control. Measurements are available from four radii at a maximum sampling frequency of 5 kHz. Post-discharge analysis of RTV data provides additional information on ion temperature, toroidal velocity and density of carbon impurities. Examples of physics studies enabled by RTV measurements from initial operations of NSTX-U are discussed.
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Download PPPL-5262 (pdf 3.9 MB 23 pp)
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