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Overview of recent physics results from the National Spherical Torus Experiment (NSTX)

  • Author(s): 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
  • Wilson, JR
  • Yuh, H
  • Zakharov, LE
  • Zhu, W
  • Zweben, SJ
  • Akers, R
  • Beiersdorfer, P
  • Betti, R
  • Bigelow, T
  • Bitter, M
  • Bonoli, P
  • Bourdelle, C
  • Chang, CS
  • Chrzanowski, J
  • Dudek, L
  • Efthimion, PC
  • Finkenthal, M
  • Fredd, E
  • Fu, GY
  • Glasser, A
  • Goldston, RJ
  • Greenough, NL
  • Grisham, LR
  • Gorelenkov, N
  • Guazzotto, L
  • Hawryluk, RJ
  • Hogan, J
  • Houlberg, W
  • Humphreys, D
  • Jaeger, F
  • Kalish, M
  • Krasheninnikov, S
  • Lao, LL
  • Lawrence, J
  • Leuer, J
  • Liu, D
  • Oliaro, G
  • Pacella, D
  • Parsells, R
  • Schaffer, M
  • Semenov, I
  • Shaing, KC
  • Shapiro, MA
  • Shinohara, K
  • Sichta, P
  • Tang, X
  • Vero, R
  • Walker, M
  • Wampler, W
  • et al.
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.

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