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1. The national spherical torus experiment (NSTX) research programme and progress towards high beta, long pulse operating scenarios

Author

Manfred Bitter, Vlad Soukhanovskii, E.D. Fredrickson, Roger Raman, R. E. Barry, Richard Majeski, G. Rewoldt, Yueng Kay Martin Peng, M.M. Menon, R. Parsells, T. Stevenson, R. Marsala, Brian Nelson, B. McCormack, E. Fredd, L.L. Lao, P. C. Efthimion, S.A. Sabbagh, Hyeon K. Park, Robert Kaita, R. E. Bell, J. Chrzanowski, M. Rensink, E.J. Doyle, Mark D. Carter, B. C. Stratton, R. Vero, K.C. Lee, Ker-Chung Shaing, Rajesh Maingi, Lei Zeng, C.E. Bush, Masayoshi Nagata, Yuichi Takase, J. Foley, William Heidbrink, J.R. Ferron, Stanley Kaye, Masayuki Ono, Peter Beiersdorfer, C.H. Skinner, G.D. Porter, C. K. Phillips, K. C. Lee, J. Manickam, T. K. Mau, E. J. Synakowski, A. von Halle, R. A. Ellis, D. Mastravito, E. Mazzucato, A. Rosenberg, David Gates, J. C. Hosea, T. Peebles, Neville C. Luhmann, G. Oliaro, J.G. Yang, W. Davis, J. Robinson, John B Wilgen, M. Williams, D.W. Swain, B.P. LeBlanc, B. H. Deng, Jonathan Menard, S. Kubota, Xian-Zhu Tang, D. Piglowski, A. L. Roquemore, M.J. Schaffer, C. Neumeyer, Clarisse Bourdelle, Wayne A Houlberg, Mark Gilmore, T.S. Bigelow, Stephen Jardin, L. Dudek, R. Hatcher, W. Blanchard, J.A. Boedo, S. S. Medley, P. Roney, H.W. Kugel, Michael Finkenthal, R. W. Harvey, W. Zhu, D. S. Darrow, D.P. Stotler, X.Q. Xu, K. W. Hill, James R. Wilson, R.J. Hawryluk, Osamu Mitarai, Robert James Goldston, F. Paoletti, G. Taylor, S.F. Paul, G. A. Wurden, Fred Levinton, Hantao Ji, P.M. Ryan, S. Ramakrishnan, P.T. Bonoli, Thomas Jarboe, M. H. Redi, M. Okabayashi, M.G. Bell, Syun'ichi Shiraiwa, D. Mueller, Choong-Seock Chang, D. Pacella, T. Gibney, B. Peneflor, Larry R. Grisham, B. Blagojevic, R.J. Akers, J. Lawrance, P. Sichta, R.I. Pinsker, William R. Wampler, Nobuhiro Nishino, Abhay K. Ram, Ricardo Maqueda, Alan H. Glasser, Stewart Zweben, Jan Egedal, R.V. Budny, Dan Stutman, M. Kalish, David Johnson, and J.M. Bialek

Subjects
Physics, Nuclear and High Energy Physics, Toroid, Physics::Plasma Physics, Beta (plasma physics), Divertor, Magnetic confinement fusion, Plasma, Atomic physics, Electric current, Spherical tokamak, Condensed Matter Physics, Bootstrap current
Abstract

A major research goal of the national spherical torus experiment is establishing long-pulse, high beta, high confinement operation and its physics basis. This research has been enabled by facility capabilities developed during 2001 and 2002, including neutral beam (up to 7?MW) and high harmonic fast wave (HHFW) heating (up to 6?MW), toroidal fields up to 6?kG, plasma currents up to 1.5?MA, flexible shape control, and wall preparation techniques. These capabilities have enabled the generation of plasmas with of up to 35%. Normalized beta values often exceed the no-wall limit, and studies suggest that passive wall mode stabilization enables this for H mode plasmas with broad pressure profiles. The viability of long, high bootstrap current fraction operations has been established for ELMing H mode plasmas with toroidal beta values in excess of 15% and sustained for several current relaxation times. Improvements in wall conditioning and fuelling are likely contributing to a reduction in H mode power thresholds. Electron thermal conduction is the dominant thermal loss channel in auxiliary heated plasmas examined thus far. HHFW effectively heats electrons, and its acceleration of fast beam ions has been observed. Evidence for HHFW current drive is obtained by comparision of the loop voltage evolution in plasmas with matched density and temperature profiles but varying phases of launched HHFW waves. Studies of emissions from electron Bernstein waves indicate a density scale length dependence of their transmission across the upper hybrid resonance near the plasma edge that is consistent with theoretical predictions. A peak heat flux to the divertor targets of 10?MW?m?2 has been measured in the H mode, with large asymmetries being observed in the power deposition between the inner and outer strike points. Non-inductive plasma startup studies have focused on coaxial helicity injection. With this technique, toroidal currents up to 400?kA have been driven, and studies to assess flux closure and coupling to other current drive techniques have begun.

Published
2003
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2. Overview of the initial NSTX experimental results

Author

K. W. Hill, Fred Levinton, R.J. Hawryluck, E. Mazzucato, M. Williams, Hantao Ji, T. Stevenson, D. S. Darrow, D. Mueller, K. C. Lee, S.F. Paul, E. J. Synakowski, Robert Kaita, W. Zhu, Neville C. Luhmann, G. A. Wurden, B. C. Stratton, R. Hatcher, Stanley Kaye, Xueqiao Xu, William R. Wampler, Abhay K. Ram, D.W. Swain, Stewart Zweben, R. E. Bell, R. A. Ellis, Dan Stutman, P.M. Ryan, M. Kalish, A. von Halle, J.M. Bialek, R. Parsells, H. Hayashiya, M.J. Schaffer, Thomas Jarboe, T. Peebles, W. Blanchard, P. Roney, E. J. Doyle, L.L. Lao, John B Wilgen, C. Neumeyer, Syun'ichi Shiraiwa, T. Gibney, C.H. Skinner, S. Kubota, P. H. LaMarche, C. K. Phillips, J. Manickam, S.A. Sabbagh, J.G. Yang, Ricardo Maqueda, Abraham Bers, R. Raman, W. Davis, J. Chrzanowski, David Johnson, Osamu Mitarai, H.W. Kugel, James R. Wilson, B. A. Nelson, Richard Majeski, J. Robinson, Hyeon K. Park, G. Pearson, R. I. Pinsker, A. Rosenberg, D.P. Stotler, P. C. Efthimion, P.T. Bonoli, G.D. Porter, E. Fredd, Stephen Jardin, Nobuhiro Nishino, David Gates, Robert James Goldston, Lei Zeng, S. Ramakrishnan, Masayoshi Nagata, Yuichi Takase, R. Ackers, Yueng Kay Martin Peng, E.D. Fredrickson, L. Dudek, M.M. Menon, Michael Finkenthal, M.G. Bell, Masayuki Ono, Larry R. Grisham, P. Sichta, R. Marsala, Rajesh Maingi, A. L. Roquemore, T.S. Bigelow, T. K. Mau, S. S. Medley, G. Oliaro, Jonathan Menard, G. Taylor, R. E. Barry, B. McCormack, Mark D. Carter, J.R. Ferron, F. Paoletti, Manfred Bitter, J. C. Hosea, and B.P. LeBlanc

Subjects
Physics, Nuclear and High Energy Physics, Toroid, Plasma shaping, Solenoid, Torus, Plasma, Electric current, Coaxial, Atomic physics, Condensed Matter Physics, Joule heating
Abstract

The main aim of the National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the spherical torus (ST) concept. The NSTX device began plasma operations in February 1999 and the plasma current Ip was successfully brought up to the design value of 1 MA on 14 December 1999. The planned plasma shaping parameters, elongation κ = 1.6-2.2 and triangularity δ = 0.2-0.4, were achieved in inner wall limited, and single null and double null diverted configurations. The coaxial helicity injection (CHI) and high harmonic fast wave (HHFW) experiments were also initiated. CHI current of 27 kA produced up to 260 kA toroidal current without using an ohmic solenoid. With the injection of 2.3 MW of HHFW power, using 12 antennas connected to six transmitters, electrons were heated from a central temperature of 400 eV to 900 eV at a central density of 3.5 × 1013 cm-3, increasing the plasma energy to 59 kJ and the toroidal β, βT, to 10%. The NBI system commenced operation in September 2000. The initial results with two ion sources (PNBI = 2.8 MW) show good heating, producing a total plasma stored energy of 90 kJ corresponding to βT ≈ 18% at a plasma current of 1.1 MA.

Published
2001
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3. The KSTAR project: An advanced steady state superconducting tokamak experiment

Author

G.S Lee, J Kim, S.M Hwang, C.S Chang, H.Y Chang, M.H Cho, B.H Choi, K Kim, K.W Cho, S Cho, K.K Choh, C.H Choi, J.H Choi, J.W Choi, I.S Choi, C.J Do, T.H Ha, J.H Han, J.S Hong, K.H Hong, N.I Hur, I.S Hwang, K.H Im, H.G Jhang, Y.S Jung, B.C Kim, D.L Kim, G.H Kim, H.S Kim, J.S Kim, J.Y Kim, W.C Kim, Y.S Kim, K.H Kwon, M.C Kyum, B.J Lee, D.K Lee, H.G Lee, J.M Lee, S.G Lee, H.G Na, Y.K Oh, J.H Park, H.C Ri, Y.S Ryoo, K.Y Song, H.L Yang, J.G Yang, B.J Yoo, S.J Yoo, N.S Yoon, S.B Yoon, G.H You, K.I You, W Choe, D.-I Choi, S.G Jeong, D.Y Lee, Y.S Bae, H.S Kang, G.N Kim, I.S Ko, W Namkung, J.S Oh, Y.D Bae, Y.S Cho, B.G Hong, G Hong, C.K Hwang, S.R In, M.H Ju, H.J Lee, B.H Oh, B.J Yoon, S Baang, H.J Choi, J Hwang, M.G Kim, Y.J Kim, S.I Lee, J Yee, C.S Yoon, K.-H Chung, S.H Hong, Y.S Hwang, S.H Kim, Y.H Kim, K.H Chung, J.Y Lim, D.W Ha, S.S Oh, K.S Ryu, Q.L Wang, T.K Ko, J Joo, S Suh, J.H Lee, Y.W Lee, H.S Shin, I.H Song, J Baek, I.Y Han, Y Koh, P.Y Park, C Ryu, J.J Cho, D.M Hwang, J.A Schmidt, H.K Park, G.H Neilson, W.T Reiersen, R.T Simmons, S Bernabei, F Dahlgren, L.R Grisham, S.C Jardin, C.E Kessel, J Manickam, S.S Medley, N Pomphrey, J.C Sinnis, T.G Brown, R.B White, K.M Young, J Schultz, P.W Wang, L Sevier, M.D Carter, P.M Ryan, D.W Swain, D.N Hill, W.M Nevins, and B.J Braams

Subjects
Physics, Nuclear and High Energy Physics, Tokamak, Divertor, Nuclear engineering, Cyclotron, Pulse duration, Plasma, Fusion power, Condensed Matter Physics, law.invention, Nuclear magnetic resonance, law, Magnet, KSTAR
Abstract

The Korea Superconducting Tokamak Advanced Research (KSTAR) project is the major effort of the national fusion programme of the Republic of Korea. Its aim is to develop a steady state capable advanced superconducting tokamak to establish a scientific and technological basis for an attractive fusion reactor. The major parameters of the tokamak are: major radius 1.8 m, minor radius 0.5 m, toroidal field 3.5 T and plasma current 2 MA, with a strongly shaped plasma cross-section and double null divertor. The initial pulse length provided by the poloidal magnet system is 20 s, but the pulse length can be increased to 300 s through non-inductive current drive. The plasma heating and current drive system consists of neutral beams, ion cyclotron waves, lower hybrid waves and electron cyclotron waves for flexible profile control in advanced tokamak operating modes. A comprehensive set of diagnostics is planned for plasma control, performance evaluation and physics understanding. The project has completed its conceptual design and moved to the engineering design and construction phase. The target date for the first plasma is 2002.

Published
2000
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