PPPL-3511 is available in <a href="PPPL-3511.pdf">pdf</a> or 
<a href="PPPL-3511.ps">postscript</a> formats.

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<b>Flux Consumption Optimization and the Achievement of 1 MA Discharge on NSTX</b>
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Authors: J. Menard, B. LeBlanc, M. Bell, R. Bell, E. Fredrickson, D. Gates, S. Jardin, S. Kaye, H. Kugel, D. Mueller, S. Paul, C.H. Skinner, S.A. Sabbagh, R. Maingi, R. Maqueda, D. Stutman, and the NSTX Research Team
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<b>Date of PPPL Report:</b> November 2000
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<b>Presented at:</b> the 18th International Atomic Energy Agency's (IAEA) Fusion Energy Conference 2000 (FEC-2000) held in Sorrento, Italy, October 4-10, 2000. An unedited proceedings will be published by IAEA in electronic format (CD-ROM) only.
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The spherical tokamak (ST), because of its slender central column, has very limited volt-second capability relative to a standard aspect ratio tokamak of similar plasma cross-section. Recent experiments on the National Spherical Torus Experiment (NSTX) have begun to quantify and optimize the ohmic current drive efficiency in a MA-class ST device. Sustainable ramp-rates in excess of 5MA/sec during the current rise phase have been achieved on NSTX, while faster ramps generate significant MHD activity. Discharges with <font face ="times"><i>I<sub>P</sub></i></font> exceeding 1MA have been achieved in NSTX with nominal parameters: aspect ratio A=1.3-1.4, elongation <font face ="symbol">k</font>=2-2.2, triangularity <font face ="symbol">d</font>=0.4, internal inductance li=0.6, and Ejima coefficient <i>C<sub>E</sub></i>=0.35. Flux consumption efficiency results, performance improvements associated with first boronization, and comparisons to neo-classical resistivity are described.

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