Initial physics results from the National Spherical Torus Experiment

Journal Article · Mon Jan 01 00:00:00 EST 2001 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.1343089· OSTI ID:1081849

Kaye, S. M.; Bell, M. G.; Bell, R. E.; Bialek, J.; Bigelow, T.; Bitter, M.; Bonoli, P.; Darrow, D.; Efthimion, P.; Ferron, J.; Fredrickson, E.; Gates, D.; Grisham, L.; Hosea, J.; Johnson, D.; Kaita, R.; Kubota, S.; Kugel, H.; LeBlanc, B.; Maingi, R. ; Manickam, J.; Mau, T. K.; Maqueda, R. J.; Mazzucato, E.; Menard, J.; Mueller, D.; Nelson, B.; Nishino, N.; Ono, M.; Paoletti, F.; Paul, S.; Peng, Y-K. M.; Phillips, C. K.; Raman, R.; Ryan, P.; Sabbagh, S. A.; Schaffer, M.; Skinner, C. H.; Stutman, D.; Swain, D.; Synakowski, E.; Takase, Y.; Wilgen, J.; Wilson, J. R.; Zhu, W.; Zweben, S.; Bers, A.; Carter, M.; Deng, B.; Domier, C.; Doyle, E.; Finkenthal, M.; Hill, K.; Jarboe, T.; Jardin, S.; Ji, H.; Lao, L.; Lee, K. C.; Luhmann, N.; Majeski, R.; Medley, S.; Park, H.; Peebles, T.; Pinsker, R. I.; Porter, G.; Ram, A.; Rensink, M.; Rognlien, T.; Stotler, D.; Stratton, B.; Taylor, G.; Wampler, W.; Wurden, G. A.; Xu, X. Q.; Zeng, L.

The mission of the National Spherical Torus Experiment (NSTX) is to extend the understanding of toroidal physics to low aspect ratio (R/a approx-equal 1.25) in low collisionality regimes. NSTX is designed to operate with up to 6 MW of high harmonic fast wave (HHFW) heating and current drive, 5 MW of neutral beam injection (NBI) and co-axial helicity injection (CHI) for noninductive startup. Initial experiments focused on establishing conditions that will allow NSTX to achieve its aims of simultaneous high β_t and high-bootstrap current fraction, and to develop methods for noninductive operation, which will be necessary for Spherical Torus power plants. Ohmic discharges with plasma currents up to 1 MA and with a range of shapes and configurations were produced. Density limits in deuterium and helium reached 80% and 120% of the Greenwald limit, respectively. Significant electron heating was observed with up to 2.3 MW of HHFW. Up to 270 kA of toroidal current for up to 200 ms was produced noninductively using CHI. Initial NBI experiments were carried out with up to two beam sources (3.2 MW). Plasmas with stored energies of up to 140 kJ and β_t = 21% were produced.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• Contributing Organization: NSTX Team
• DOE Contract Number: AC05-00OR22725; AC02-76CH03073; AC05-96OR22464; FG06-90ER54095; FG02-89ER53297; W-7405-ENG-36; AC03-99ER54463; AC04-94AL85000; FG02-99ER-54521
• OSTI ID: 1081849
• Journal Information: Physics of Plasmas, Vol. 8, Issue 5; ISSN 1070-664X: PHPAEN
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English