Overview of physics results from NSTX

R. Raman, J. W. Ahn, J. P. Allain, R. Andre, R. Bastasz, D. Battaglia, P. Beiersdorfer, M. Bell, R. Bell, E. Belova, J. Berkery, R. Betti, J. Bialek, T. Bigelow, M. Bitter, J. Boedo, P. Bonoli, A. Boozer, A. Bortolon, D. BrennanJ. Breslau, R. Buttery, J. Canik, G. Caravelli, C. Chang, N. A. Crocker, D. Darrow, W. Davis, L. Delgado-Aparicio, A. Diallo, S. Ding, D. D'Ippolito, C. Domier, W. Dorland, S. Ethier, T. Evans, J. Ferron, M. Finkenthal, J. Foley, R. Fonck, R. Frazin, E. Fredrickson, G. Fu, D. Gates, S. Gerhardt, A. Glasser, N. Gorelenkov, T. Gray, Y. Guo, W. Guttenfelder, T. Hahm, R. Harvey, A. Hassanein, W. Heidbrink, K. Hill, Y. Hirooka, E. B. Hooper, J. Hosea, B. Hu, D. Humphreys, K. Indireshkumar, F. Jaeger, T. Jarboe, S. Jardin, M. Jaworski, R. Kaita, J. Kallman, O. Katsuro-Hopkins, S. Kaye, C. Kessel, J. Kim, E. Kolemen, S. Krasheninnikov, S. Kubota, H. Kugel, R. La Haye, L. Lao, B. Leblanc, W. Lee, K. Lee, J. Leuer, F. Levinton, Y. Liang, D. Liu, N. Luhmann, R. Maingi, R. Majeski, J. Manickam, D. Mansfield, R. Maqueda, E. Mazzucato, A. McLean, D. McCune, B. McGeehan, G. McKee, S. Medley, J. Menard, M. Menon, H. Meyer, D. Mikkelsen, G. Miloshevsky, D. Mueller, T. Munsat, J. Myra, B. Nelson, N. Nishino, R. Nygren, M. Ono, T. Osborne, H. Park, J. Park, S. Paul, W. Peebles, B. Penaflor, C. Phillips, A. Pigarov, M. Podesta, J. Preinhaelter, Y. Ren, H. Reimerdes, G. Rewoldt, P. Ross, C. Rowley, E. Ruskov, D. Russell, D. Ruzic, P. Ryan, S. A. Sabbagh, M. Schaffer, E. Schuster, F. Scotti, K. Shaing, V. Shevchenko, K. Shinohara, V. Sizyuk, C. H. Skinner, A. Smirnov, D. Smith, P. Snyder, W. Solomon, A. Sontag, V. Soukhanovskii, T. Stoltzfus-Dueck, D. Stotler, B. Stratton, D. Stutman, H. Takahashi, Y. Takase, N. Tamura, X. Tang, C. N. Taylor, G. Taylor, C. Taylor, K. Tritz, D. Tsarouhas, M. Umansky, J. Urban, M. Walker, W. Wampler, W. Wang, J. Whaley, R. White, J. Wilgen, R. Wilson, K. L. Wong, J. Wright, Z. Xia, D. Youchison, G. Yu, H. Yuh, L. Zakharov, D. Zemlyanov, G. Zimmer, S. J. Zweben

Research output: Contribution to journalReview article

Abstract

In the last two experimental campaigns, the low aspect ratio NSTX has explored physics issues critical to both toroidal confinement physics and ITER. Experiments have made extensive use of lithium coatings for wall conditioning, correction of non-axisymmetric field errors and control of n = 1 resistive wall modes (RWMs) to produce high-performance neutral-beam heated discharges extending to 1.7 s in duration with non-inductive current fractions up to 0.7. The RWM control coils have been used to trigger repetitive ELMs with high reliability, and they have also contributed to an improved understanding of both neoclassical tearing mode and RWM stabilization physics, including the interplay between rotation and kinetic effects on stability. High harmonic fast wave (HHFW) heating has produced plasmas with central electron temperatures exceeding 6 keV. The HHFW heating was used to show that there was a 20-40% higher power threshold for the L-H transition for helium than for deuterium plasmas. A new diagnostic showed a depletion of the fast-ion density profile over a broad spatial region as a result of toroidicity-induced Alfvén eigenmodes (TAEs) and energetic-particle modes (EPMs) bursts. In addition, it was observed that other modes (e.g. global Alfvén eigenmodes) can trigger TAE and EPM bursts, suggesting that fast ions are redistributed by high-frequency AEs. The momentum pinch velocity determined by a perturbative technique decreased as the collisionality was reduced, although the pinch to diffusion ratio, Vpinch/χ, remained approximately constant. The mechanisms of deuterium retention by graphite and lithium-coated graphite plasma-facing components have been investigated. To reduce divertor heat flux, a novel divertor configuration, the 'snowflake' divertor, was tested in NSTX and many beneficial aspects were found. A reduction in the required central solenoid flux has been realized in NSTX when discharges initiated by coaxial helicity injection were ramped in current using induction. The resulting plasmas have characteristics needed to meet the objectives of the non-inductive start-up and ramp-up program of NSTX.

Original languageEnglish (US)
Article number094011
JournalNuclear Fusion
Volume51
Issue number9
DOIs
StatePublished - Sep 2011

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Fingerprint Dive into the research topics of 'Overview of physics results from NSTX'. Together they form a unique fingerprint.

  • Cite this

    Raman, R., Ahn, J. W., Allain, J. P., Andre, R., Bastasz, R., Battaglia, D., Beiersdorfer, P., Bell, M., Bell, R., Belova, E., Berkery, J., Betti, R., Bialek, J., Bigelow, T., Bitter, M., Boedo, J., Bonoli, P., Boozer, A., Bortolon, A., ... Zweben, S. J. (2011). Overview of physics results from NSTX. Nuclear Fusion, 51(9), [094011]. https://doi.org/10.1088/0029-5515/51/9/094011