PPPL-3716 is available in <a href="PPPL-3716.pdf">pdf</a> format (352 KB).

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<b>Recent Progress on the National Spherical Torus Experiment (NSTX)
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<b>Authors:</b> D.A. Gates, M.G. Bell, R.E. Bell, J. Bialek, T. Bigelow, et al.
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<b>Date of PPPL Report:</b> July 2002
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<b>Presented at:</b> the 29th European Physical Society Conference on Plasma Physics and Controlled Fusion, June 17-21, 2002, in Montreux, Switzerland.
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Recent upgrades to the NSTX facility have led to improved plasma performance. Using 5MW of neutral beam injection, plasmas with toroidal Beta<sub>T</sub> (= 2<font face="symbol">m<sub>0</sub></font>&#60;p&#62;/Beta<sub>T</sub><sup>2</sup>  where Beta<sub>T</sub> is the vacuum toroidal field at the plasma geometric center) > 30&#37; have been achieved with normalized Beta<sub>N</sub> (= Beta<sub>T</sub>aBeta<font face="symbol"><sub>I</sub>/I</font><sub>P</sub>) approximately 6 % <sup>&#46;</sup>m<sup>&#46;</sup>T/MA. The highest Beta discharge exceeded the calculated no-wall Beta limit for several wall times. The stored energy has reached 390kJ at higher toroidal field (0.55T) corresponding to Beta<sub>T</sub> approximately 20&#37; and Beta<sub>N</sub> = 5.4. Long pulse (~1s) high Beta<sub>p</sub> (~1.5) discharges have also been obtained at higher Beta<sub><font face ="symbol">f </sub></font>(0.5T) with up to 6MW NBI power. The highest energy confinement times, up to 120ms, were observed during H-mode operation which is now routine. Confinement times of ~ 1.5 times ITER98pby2 for several tau<sub>E</sub> are observed during both H-Mode and non-H-Mode discharges. Calculations indicate that many NSTX discharges have very good ion confinement, approaching neoclassical levels. High Harmonic Fast Wave current drive has been demonstrated by comparing discharges with waves launched parallel and anti-parallel to the plasma current.




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