1. Overview of recent physics results from the National Spherical Torus Experiment (NSTX)
- Author
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Menard, JE, Bell, MG, Bell, RE, Bernabei, S, Bialek, J, Biewer, T, Blanchard, W, Boedo, J, Bush, CE, Carter, MD, Choe, W, Crocker, NA, Darrow, DS, Davis, W, Delgado-Aparicio, L, Diem, S, Domier, CW, D'Ippolito, DA, Ferron, J, Field, A, Foley, J, Fredrickson, ED, Gates, DA, Gibney, T, Harvey, R, Hatcher, RE, Heidbrink, W, Hill, KW, Hosea, JC, Jarboe, TR, Johnson, DW, Kaita, R, Kaye, SM, Kessel, CE, Kubota, S, Kugel, HW, Lawson, J, LeBlanc, BP, Lee, KC, Levinton, FM, Luhmann, NC, Maingi, R, Majeski, RP, Manickam, J, Mansfield, DK, Maqueda, R, Marsala, R, Mastrovito, D, Mau, TK, Mazzucato, E, Medley, SS, Meyer, H, Mikkelsen, DR, Mueller, D, Munsat, T, Myra, JR, Nelson, BA, Neumeyer, C, Nishino, N, Ono, M, Park, HK, Park, W, Paul, SF, Peebles, T, Peng, M, Phillips, C, Pigarov, A, Pinsker, R, Ram, A, Ramakrishnan, S, Raman, R, Rasmussen, D, Redi, M, Rensink, M, Rewoldt, G, Robinson, J, Roney, P, Roquemore, AL, Ruskov, E, Ryan, P, Sabbagh, SA, Schneider, H, Skinner, CH, Smith, DR, Sontag, A, Soukhanovskii, V, Stevenson, T, Stotler, D, Stratton, BC, Stutman, D, Swain, D, Synakowski, E, Takase, Y, Taylor, G, Tritz, K, von Halle, A, Wade, M, White, R, Wilgen, J, and Williams, M
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Atomic ,Molecular ,Nuclear ,Particle and Plasma Physics ,Fluids & Plasmas - Abstract
The National Spherical Torus Experiment (NSTX) has made considerable progress in advancing the scientific understanding of high performance long-pulse plasmas needed for future spherical torus (ST) devices and ITER. Plasma durations up to 1.6 s (five current redistribution times) have been achieved at plasma currents of 0.7 MA with non-inductive current fractions above 65% while simultaneously achieving βT and βN values of 17% and 5.7 (%m T MA-1), respectively. A newly available motional Stark effect diagnostic has enabled validation of current-drive sources and improved the understanding of NSTX 'hybrid'-like scenarios. In MHD research, ex-vessel radial field coils have been utilized to infer and correct intrinsic EFs, provide rotation control and actively stabilize the n ≤ 1 resistive wall mode at ITER-relevant low plasma rotation values. In transport and turbulence research, the low aspect ratio and a wide range of achievable β in the NSTX provide unique data for confinement scaling studies, and a new microwave scattering diagnostic is being used to investigate turbulent density fluctuations with wavenumbers extending from ion to electron gyro-scales. In energetic particle research, cyclic neutron rate drops have been associated with the destabilization of multiple large toroidal Alfven eigenmodes (TAEs) analogous to the 'sea-of-TAE' modes predicted for ITER, and three-wave coupling processes have been observed for the first time. In boundary physics research, advanced shape control has enabled studies of the role of magnetic balance in H-mode access and edge localized mode stability. Peak divertor heat flux has been reduced by a factor of 5 using an H-mode-compatible radiative divertor, and lithium conditioning has demonstrated particle pumping and results in improved thermal confinement. Finally, non-solenoidal plasma start-up experiments have achieved plasma currents of 160 kA on closed magnetic flux surfaces utilizing coaxial helicity injection. © 2007 IAEA.
- Published
- 2007