null J.E. Menard, null R.E.Bell, null C. Bourdelle, null D.S. Darrow, null E.D. Fredrickson, null D.A. Gates, null L.R. Grisham, null S.M. Kaye, null B.P. LeBlanc, null R. Maingi, null S.S. Medley, null D. Mueller, null F. Paoletti, null S.A. Sabbagh, null D. Stutman, null D.W. Swain, null J.R. Wilson, null M.G. Bell, null J.M. Bialek, null C.E.Bush, null J.C. Hosea, null D.W. Johnson, null R. Kaita, null H.W. Kugel, null R.J. Maqueda, null M. Ono, null Y-K.M. Peng, null C.H. Skinner, null V.A. Soukhanovskii, null E.J. Synakowski, null G. Taylor, null G.A. Wurden, and null and S.J. Zweben
The National Spherical Torus Experiment (NSTX) is a spherical tokamak with nominal plasma major radius R(subscript ''0'') = 0.85 m, minor radius a = 0.66 m, and aspect ratio A > 1.28. Typical discharge parameters are plasma current I (subscript ''p'') = 0.7-1.4 MA, toroidal magnetic field B(subscript ''t0'') = 0.25-0.45 Tesla at major radius R(subscript ''0''), elongation = 1.7-2.2, triangularity 0.3-0.5, line-average electron density = 2-5 x 10(superscript ''19'') m(superscript ''-3''), electron temperature T(subscript ''e'')(0) = 0.5-1.5 keV, and ion temperature T(subscript ''i'')(0) = 0.5-2 keV. The NSTX auxiliary heating systems can routinely deliver 4.5 MW of 80-keV deuterium neutral beams and 3 MW of 30-MHz high-harmonic fast-wave power. Kinetic profile diagnostics presently include a 10-channel, 30-Hz multipulse Thomson scattering system (MPTS), a 17-channel charge-exchange recombination spectroscopy (CHERS) system, a 48-chord ultra-soft X-ray (USXR) array, and a 15-chord bolometry array. Initial experiments utilizing auxiliary heating on NSTX have focused on MHD stability limits, confinement trends, studying H-mode characteristics, and performing initial power balance calculations.