Bulletin of the American Physical Society
58th Annual Meeting of the APS Division of Plasma Physics
Volume 61, Number 18
Monday–Friday, October 31–November 4 2016; San Jose, California
Session PP10: Poster Session VI (MFE: Energetic Particles, Heating, Current Drive and Fusion System Design; MFE: DIII-D Tokamak; ICF/HED: Diagnostics, X-Ray Sources and WDM; Pure-ion, Pure Electron, Anti-Matter Plasma and Strongly Coupled)
Wednesday, November 2, 2016
Room: Exhibit Hall 1
Abstract: PP10.00079 : Real-Time Variation of the Injected Neutral Beam Energy on the DIII-D Tokamak,*
A powerful new technique for smoothly controlling the time evolution of injected energy from neutral beams has recently been implemented on the DIII-D tokamak. Upgrades to the high voltage circuitry of the neutral beams and to the tokamak’s Plasma Control System have enabled the first-ever continuous variation of beam voltage during plasma shots. This avoids the perturbative effects of pulse modulation, which was the previously employed method for changing the injected beam power. The new technique allows much finer control of the injected energy, with beam voltage able to be varied smoothly over a 20 kV range (within the 45-85 kV beam operating space) in 0.5 sec. This capability enables fundamentally new experiments that require precise control of beam ion phase space, including the minimization of undesirable energetic ion instabilities and scans across low torque regimes at fixed power. We present a description of the beam system modifications and initial results from plasma experiments using the new variable beam energy capability on the DIII-D tokamak.
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