학술논문
Overview of recent physics results from the National Spherical Torus Experiment (NSTX)
Document Type
article
Author
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; Williams, M
Source
Nuclear Fusion. 47(10)
Subject
Language
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.