Overview of the initial NSTX experimental results

Ono, M.; Bell, M.G.; Bell, R.E.; Bigelow, T.; Bitter, M.; Blanchard, W.; Darrow, D.S.; Fredrickson, E. D.; Gates, D.; Grisham, L.; Hosea, J.; Johnson, D.; Kaita, R.; Kaye, S. M.; Kubota, S.; Kugel, H.; LeBlanc, B.P.; Maingi, R.; Maqueda, R. J.; Mazzucato, E.; Ménard, J.; Mueller, D.; Nelson, B. A.; Neumeyer, C.; Paoletti, F.; Paul, S. F.; Peng, Yi; Ramakrishnan, S.; Raman, R.; Ryan, P. M.; Sabbagh, S. A.; Skinner, C.H.; Stevenson, T.; Stutman, D.; Swain, D. W.; Synakowski, E. J.; Taylor, G.; Halle, A. von; Wilgen, J. B.; Williams, M. D.; Wilson, J. R.; Zweben, S. J.; Ackers, R.; Barry, Robert E.; Bers, A.; Bialek, J.; Bonoli, P. T.; Carter, M.D.; Chrzanowski, J.; Davis, W. M.; Doyle, E. J.; Dudek, L.; Efthimion, P. C.; Ellis, R.; Ferron, J. R.; Finkenthal, M.; Fredd, E.; Gibney, T.; Goldston, Robert James; Hatcher, R.; Hawryluck, R.J.; Hayashiya, Hitoshi; Hill, K. W.; Jarboe, T. R.; Jardin, S.C.; Ji, Hantao; Kalish, M.; LaMarche, P. H.; Lao, L. L.; Lee, K.C.; Levinton, F. M.; Luhmann, Neville C.; Majeski, R.; Manickam, J.; Marsala, R.; Mau, T. K.; McCormack, B.; Medley, S. S.; Menon, M. M.; Mitarai, O.; Nagata, Masayoshi; Nishino, Norikazu; Oliaro, G.; Park, H.K.; Parsells, R.; Pearson, Gavin; Peebles, T.; Phillips, C. K.; Pinsker, R. I.; Porter, G. D.; Ram, A. K.; Robinson, John A. T.; Roney, P.; Roquemore, A. L.; Rosenberg, A.; Schaffer, M. J.; Shiraiwa, S.; Sichta, P.; Stotler, D.P.; Stratton, B. C.; Takase, Y.; Wampler, W.R.; Wurden, G. A.; Xu, X. Q.; Yang, J. G.; Zeng, L.; Zhu, W.

doi:10.1088/0029-5515/41/10/311

Cited by 58 publications

(39 citation statements)

References 21 publications

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“…The National Spherical Torus Experiment (NSTX) [1] is being upgraded to NSTX-U, a device that will have double the toroidal field, plasma current and neutral beam injection (NBI) power, and a pulse length of 5-8 s, five times the pulse length of NSTX [2]. In NSTX-U the maximum axial toroidal field will be 1 T, and the maximum plasma current will be 2 MA.…”

Section: Introductionmentioning

confidence: 99%

ECRH/EBWH system for NSTX-U

Taylor

Ellis

Harvey

et al. 2012

EPJ Web of Conferences

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Abstract. The National Spherical Torus Experiment Upgrade (NSTX-U) will operate at an axial toroidal field of up to 1 T, about twice the field available on NSTX. A 28 GHz electron cylotron resonance heating (ECRH) system is currently being planned for NSTX-U. A 1 MW 28 GHz gyrotron will be employed. Intially the system will use short, 10-50 ms, 1 MW pulses for ECRH-assisted discharge start-up. Later the pulse length will be extended to 1-5 s to study electron Bernstein wave heating (EBWH) during the plasma current flat top. A mirror launcher will be used to couple microwave power to the plasma via O-mode to the slow X-mode to EBW (O-X-B) double mode conversion. This paper presents a pre-conceptual design for the ECRH/EBWH system proposed for NSTX-U and includes ray tracing and Fokker-Planck modeling results for 28 GHz ECRH during plasma start-up and EBW heating and current drive during the plasma current flattop of a NSTX-U advanced H-mode plasma scenario.

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Section: Introductionmentioning

confidence: 99%

ECRH/EBWH system for NSTX-U

Taylor

Ellis

Harvey

et al. 2012

EPJ Web of Conferences

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“…1 The toroidal field utilization is essentially a measure of the toroidal field required for kink stability and is thus a metric of performance of the ST. Figure 1 also gives a rough illustration of the region of this space for several ST devices. Pegasus can be seen to cover the space between the low aspect ratio mainline ST experiments such as the Small Tight Aspect Ratio Tokamak ͑START͒, 6 the National Spherical Torus Experiment ͑NSTX͒, 7 and the Mega-Amp Spherical Tokamak ͑MAST͒ 8 and the rod-stabilized spheromak experiments such as TS-3 9,10 and TS-4. In this paper, initial results from the operation of the Pegasus Toroidal Experiment will be reported.…”

Section: Introductionmentioning

confidence: 99%

Performance and stability of near-unity aspect ratio plasmas in the Pegasus Toroidal Experiment

et al. 2003

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The Pegasus Toroidal Experiment ͓R. Fonck et al., Bull. Am. Phys. Soc. 41, 1400 ͑1996͔͒ is a spherical torus designed to study the limits of plasma behavior as the aspect ratio A approaches unity. Access to near-unity A is achieved through the use of a novel high-stress reinforced solenoid magnet. High toroidal beta ␤ t is obtained in ohmically-heated plasmas by operation at low field with densities up to the Greenwald limit. Values of ␤ t up to 20% and normalized beta up to 5 have been obtained. The ratio of plasma current to toroidal field rod current, known as the toroidal field utilization, reaches values as large as 1 but appears to approach a ''soft'' boundary at that level related to both ohmic flux limitations and the onset of resistive magnetohydrodynamic ͑MHD͒ activity. The m/nϭ2/1 and 3/2 modes are most frequently observed, in agreement with the inferred safety factor profiles. Experiments are beginning to access the external kink stability boundary at edge safety factor q 95 ϭ5, which is significantly higher than that observed in conventional tokamaks. Calculations using the DCON code ͓A. H. Glasser and M. S. Chance, Bull. Am. Phys. Soc. 42, 1848 ͑1997͔͒ confirm instability to the ideal kink.

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“…The research program is aimed at extending the understanding toroidal confinement physics at low aspect ratio in collisionless, high-β regimes and to demonstrate non-inductive current generation and sustainment [12,13]. A range of plasma shapes and configurations have …”

Section: Introductionmentioning

confidence: 99%

Effect of boronization on ohmic plasmas in NSTX

et al. 2002

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Abstract:Boronization of the National Spherical Torus Experiment (NSTX) has enabled access to higher density, higher confinement plasmas. A glow discharge with 4 mTorr helium and 10% deuterated trimethyl boron deposited 1.7 g of boron on the plasma facing surfaces. Ion beam analysis of witness coupons showed a B+C areal density of 10 18 (B+C) cm -2 corresponding to a film thickness of 100 nm. Subsequent ohmic discharges showed oxygen emission lines reduced by x15, carbon emission reduced by two and copper reduced to undetectable levels. After boronization, the plasma current flattop time increased by 70% enabling access to higher density, higher confinement plasmas.

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Overview of the initial NSTX experimental results

Cited by 58 publications

References 21 publications

ECRH/EBWH system for NSTX-U

ECRH/EBWH system for NSTX-U

Performance and stability of near-unity aspect ratio plasmas in the Pegasus Toroidal Experiment

Effect of boronization on ohmic plasmas in NSTX

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