Overview of results from the national spherical torus experiment (NSTX)

D. A. Gates, J. Ahn, J. Allain, R. Andre, R. Bastasz, M. Bell, R. Bell, E. Belova, J. Berkery, R. Betti, J. Bialek, T. Biewer, T. Bigelow, M. Bitter, J. Boedo, P. Bonoli, A. Boozer, D. Brennan, J. Breslau, D. BrowerC. Bush, J. Canik, G. Caravelli, M. Carter, J. Caughman, C. Chang, W. Choe, N. Crocker, D. Darrow, L. Delgado-Aparicio, S. Diem, D. D'Ippolito, C. Domier, W. Dorland, P. Efthimion, A. Ejiri, N. Ershov, T. Evans, E. Feibush, M. Fenstermacher, J. Ferron, M. Finkenthal, J. Foley, R. Frazin, E. Fredrickson, G. Fu, H. Funaba, S. Gerhardt, A. Glasser, N. Gorelenkov, L. Grisham, T. Hahm, R. Harvey, A. Hassanein, W. Heidbrink, K. Hill, J. Hillesheim, D. Hillis, Y. Hirooka, J. Hosea, B. Hu, D. Humphreys, T. Idehara, K. Indireshkumar, A. Ishida, F. Jaeger, T. Jarboe, S. Jardin, M. Jaworski, H. Ji, H. Jung, R. Kaita, J. Kallman, O. Katsuro-Hopkins, K. Kawahata, E. Kawamori, S. Kaye, C. Kessel, J. Kim, H. Kimura, E. Kolemen, S. Krasheninnikov, P. Krstic, S. Ku, 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, D. McCune, B. McGeehan, G. McKee, S. Medley, J. Menard, M. Menon, H. Meyer, D. Mikkelsen, G. Miloshevsky, O. Mitarai, D. Mueller, S. Mueller, T. Munsat, J. Myra, Y. Nagayama, B. Nelson, X. Nguyen, N. Nishino, M. Nishiura, R. Nygren, M. Ono, T. Osborne, D. Pacella, H. Park, J. Park, S. Paul, W. Peebles, B. Penaflor, M. Peng, C. Phillips, A. Pigarov, M. Podesta, J. Preinhaelter, A. Ram, R. Raman, D. Rasmussen, A. Redd, H. Reimerdes, G. Rewoldt, P. Ross, C. Rowley, E. Ruskov, D. Russell, D. Ruzic, P. Ryan, S. Sabbagh, M. Schaffer, E. Schuster, S. Scott, K. Shaing, P. Sharpe, V. Shevchenko, K. Shinohara, V. Sizyuk, C. Skinner, A. Smirnov, D. Smith, S. Smith, P. Snyder, W. Solomon, A. Sontag, V. Soukhanovskii, T. Stoltzfus-Dueck, D. Stotler, T. Strait, B. Stratton, D. Stutman, R. Takahashi, Y. Takase, N. Tamura, X. Tang, G. Taylor, C. Taylor, C. Ticos, K. Tritz, D. Tsarouhas, A. Turrnbull, G. Tynan, M. Ulrickson, M. Umansky, J. Urban, E. Utergberg, M. Walker, W. Wampler, J. Wang, W. Wang, A. Welander, J. Whaley, R. White, J. Wilgen, R. Wilson, K. Wong, J. Wright, Z. Xia, X. Xu, D. Youchison, G. Yu, H. Yuh, L. Zakharov, D. Zemlyanov, S. Zweben

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

The mission of the National Spherical Torus Experiment (NSTX) is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high β operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale length. Results from n = 3 braking studies are consistent with the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of high harmonic fast-waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap current fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance li ∼ 0.4 with strong shaping (κ ∼ 2.7, δ ∼ 0.8) with βN approaching the with-wall β-limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction fNI ∼ 71%. Instabilities driven by super-Alfvénic ions will be an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfvénic. Linear toroidal Alfvén eigenmode thresholds and appreciable fast ion loss during multi-mode bursts are measured and these results are compared with theory. The impact of n > 1 error fields on stability is an important result for ITER. Resistive wall mode/resonant field amplification feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with β above the no-wall limit. Other highlights are results of lithium coating experiments, momentum confinement studies, scrape-off layer width scaling, demonstration of divertor heat load mitigation in strongly shaped plasmas and coupling of coaxial helicity injection plasmas to ohmic heating ramp-up. These results advance the ST towards next step fusion energy devices such as NHTX and ST-CTF.

Original languageEnglish (US)
Article number104016
JournalNuclear Fusion
Volume49
Issue number10
DOIs
StatePublished - Sep 21 2009

Fingerprint

test facilities
ions
lithium
coatings
transmission efficiency
electrons
braking
ramps
shear flow
inductance
surface waves
elongation
high current
bursts
temperature gradients
fusion
electron energy
injection
momentum
harmonics

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Gates, D. A., Ahn, J., Allain, J., Andre, R., Bastasz, R., Bell, M., ... Zweben, S. (2009). Overview of results from the national spherical torus experiment (NSTX). Nuclear Fusion, 49(10), [104016]. https://doi.org/10.1088/0029-5515/49/10/104016
Gates, D. A. ; Ahn, J. ; Allain, J. ; Andre, R. ; Bastasz, R. ; Bell, M. ; Bell, R. ; Belova, E. ; Berkery, J. ; Betti, R. ; Bialek, J. ; Biewer, T. ; Bigelow, T. ; Bitter, M. ; Boedo, J. ; Bonoli, P. ; Boozer, A. ; Brennan, D. ; Breslau, J. ; Brower, D. ; Bush, C. ; Canik, J. ; Caravelli, G. ; Carter, M. ; Caughman, J. ; Chang, C. ; Choe, W. ; Crocker, N. ; Darrow, D. ; Delgado-Aparicio, L. ; Diem, S. ; D'Ippolito, D. ; Domier, C. ; Dorland, W. ; Efthimion, P. ; Ejiri, A. ; Ershov, N. ; Evans, T. ; Feibush, E. ; Fenstermacher, M. ; Ferron, J. ; Finkenthal, M. ; Foley, J. ; Frazin, R. ; Fredrickson, E. ; Fu, G. ; Funaba, H. ; Gerhardt, S. ; Glasser, A. ; Gorelenkov, N. ; Grisham, L. ; Hahm, T. ; Harvey, R. ; Hassanein, A. ; Heidbrink, W. ; Hill, K. ; Hillesheim, J. ; Hillis, D. ; Hirooka, Y. ; Hosea, J. ; Hu, B. ; Humphreys, D. ; Idehara, T. ; Indireshkumar, K. ; Ishida, A. ; Jaeger, F. ; Jarboe, T. ; Jardin, S. ; Jaworski, M. ; Ji, H. ; Jung, H. ; Kaita, R. ; Kallman, J. ; Katsuro-Hopkins, O. ; Kawahata, K. ; Kawamori, E. ; Kaye, S. ; Kessel, C. ; Kim, J. ; Kimura, H. ; Kolemen, E. ; Krasheninnikov, S. ; Krstic, P. ; Ku, S. ; Kubota, S. ; Kugel, H. ; La Haye, R. ; Lao, L. ; Leblanc, B. ; Lee, W. ; Lee, K. ; Leuer, J. ; Levinton, F. ; Liang, Y. ; Liu, D. ; Luhmann, N. ; Maingi, R. ; Majeski, R. ; Manickam, J. ; Mansfield, D. ; Maqueda, R. ; Mazzucato, E. ; McCune, D. ; McGeehan, B. ; McKee, G. ; Medley, S. ; Menard, J. ; Menon, M. ; Meyer, H. ; Mikkelsen, D. ; Miloshevsky, G. ; Mitarai, O. ; Mueller, D. ; Mueller, S. ; Munsat, T. ; Myra, J. ; Nagayama, Y. ; Nelson, B. ; Nguyen, X. ; Nishino, N. ; Nishiura, M. ; Nygren, R. ; Ono, M. ; Osborne, T. ; Pacella, D. ; Park, H. ; Park, J. ; Paul, S. ; Peebles, W. ; Penaflor, B. ; Peng, M. ; Phillips, C. ; Pigarov, A. ; Podesta, M. ; Preinhaelter, J. ; Ram, A. ; Raman, R. ; Rasmussen, D. ; Redd, A. ; Reimerdes, H. ; Rewoldt, G. ; Ross, P. ; Rowley, C. ; Ruskov, E. ; Russell, D. ; Ruzic, D. ; Ryan, P. ; Sabbagh, S. ; Schaffer, M. ; Schuster, E. ; Scott, S. ; Shaing, K. ; Sharpe, P. ; Shevchenko, V. ; Shinohara, K. ; Sizyuk, V. ; Skinner, C. ; Smirnov, A. ; Smith, D. ; Smith, S. ; Snyder, P. ; Solomon, W. ; Sontag, A. ; Soukhanovskii, V. ; Stoltzfus-Dueck, T. ; Stotler, D. ; Strait, T. ; Stratton, B. ; Stutman, D. ; Takahashi, R. ; Takase, Y. ; Tamura, N. ; Tang, X. ; Taylor, G. ; Taylor, C. ; Ticos, C. ; Tritz, K. ; Tsarouhas, D. ; Turrnbull, A. ; Tynan, G. ; Ulrickson, M. ; Umansky, M. ; Urban, J. ; Utergberg, E. ; Walker, M. ; Wampler, W. ; Wang, J. ; Wang, W. ; Welander, A. ; Whaley, J. ; White, R. ; Wilgen, J. ; Wilson, R. ; Wong, K. ; Wright, J. ; Xia, Z. ; Xu, X. ; Youchison, D. ; Yu, G. ; Yuh, H. ; Zakharov, L. ; Zemlyanov, D. ; Zweben, S. / Overview of results from the national spherical torus experiment (NSTX). In: Nuclear Fusion. 2009 ; Vol. 49, No. 10.
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title = "Overview of results from the national spherical torus experiment (NSTX)",
abstract = "The mission of the National Spherical Torus Experiment (NSTX) is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high β operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale length. Results from n = 3 braking studies are consistent with the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70{\%} in H-mode as a result of reduced collisionality. Improved coupling of high harmonic fast-waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap current fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance li ∼ 0.4 with strong shaping (κ ∼ 2.7, δ ∼ 0.8) with βN approaching the with-wall β-limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction fNI ∼ 71{\%}. Instabilities driven by super-Alfv{\'e}nic ions will be an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfv{\'e}nic. Linear toroidal Alfv{\'e}n eigenmode thresholds and appreciable fast ion loss during multi-mode bursts are measured and these results are compared with theory. The impact of n > 1 error fields on stability is an important result for ITER. Resistive wall mode/resonant field amplification feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with β above the no-wall limit. Other highlights are results of lithium coating experiments, momentum confinement studies, scrape-off layer width scaling, demonstration of divertor heat load mitigation in strongly shaped plasmas and coupling of coaxial helicity injection plasmas to ohmic heating ramp-up. These results advance the ST towards next step fusion energy devices such as NHTX and ST-CTF.",
author = "Gates, {D. A.} and J. Ahn and J. Allain and R. Andre and R. Bastasz and M. Bell and R. Bell and E. Belova and J. Berkery and R. Betti and J. Bialek and T. Biewer and T. Bigelow and M. Bitter and J. Boedo and P. Bonoli and A. Boozer and D. Brennan and J. Breslau and D. Brower and C. Bush and J. Canik and G. Caravelli and M. Carter and J. Caughman and C. Chang and W. Choe and N. Crocker and D. Darrow and L. Delgado-Aparicio and S. Diem and D. D'Ippolito and C. Domier and W. Dorland and P. Efthimion and A. Ejiri and N. Ershov and T. Evans and E. Feibush and M. Fenstermacher and J. Ferron and M. Finkenthal and J. Foley and R. Frazin and E. Fredrickson and G. Fu and H. Funaba and S. Gerhardt and A. Glasser and N. Gorelenkov and L. Grisham and T. Hahm and R. Harvey and A. Hassanein and W. Heidbrink and K. Hill and J. Hillesheim and D. Hillis and Y. Hirooka and J. Hosea and B. Hu and D. Humphreys and T. Idehara and K. Indireshkumar and A. Ishida and F. Jaeger and T. Jarboe and S. Jardin and M. Jaworski and H. Ji and H. Jung and R. Kaita and J. Kallman and O. Katsuro-Hopkins and K. Kawahata and E. Kawamori and S. Kaye and C. Kessel and J. Kim and H. Kimura and E. Kolemen and S. Krasheninnikov and P. Krstic and S. Ku and S. Kubota and H. Kugel and {La Haye}, R. and L. Lao and B. Leblanc and W. Lee and K. Lee and J. Leuer and F. Levinton and Y. Liang and D. Liu and N. Luhmann and R. Maingi and R. Majeski and J. Manickam and D. Mansfield and R. Maqueda and E. Mazzucato and D. McCune and B. McGeehan and G. McKee and S. Medley and J. Menard and M. Menon and H. Meyer and D. Mikkelsen and G. Miloshevsky and O. Mitarai and D. Mueller and S. Mueller and T. Munsat and J. Myra and Y. Nagayama and B. Nelson and X. Nguyen and N. Nishino and M. Nishiura and R. Nygren and M. Ono and T. Osborne and D. Pacella and H. Park and J. Park and S. Paul and W. Peebles and B. Penaflor and M. Peng and C. Phillips and A. Pigarov and M. Podesta and J. Preinhaelter and A. Ram and R. Raman and D. Rasmussen and A. Redd and H. Reimerdes and G. Rewoldt and P. Ross and C. Rowley and E. Ruskov and D. Russell and D. Ruzic and P. Ryan and S. Sabbagh and M. Schaffer and E. Schuster and S. Scott and K. Shaing and P. Sharpe and V. Shevchenko and K. Shinohara and V. Sizyuk and C. Skinner and A. Smirnov and D. Smith and S. Smith and P. Snyder and W. Solomon and A. Sontag and V. Soukhanovskii and T. Stoltzfus-Dueck and D. Stotler and T. Strait and B. Stratton and D. Stutman and R. Takahashi and Y. Takase and N. Tamura and X. Tang and G. Taylor and C. Taylor and C. Ticos and K. Tritz and D. Tsarouhas and A. Turrnbull and G. Tynan and M. Ulrickson and M. Umansky and J. Urban and E. Utergberg and M. Walker and W. Wampler and J. Wang and W. Wang and A. Welander and J. Whaley and R. White and J. Wilgen and R. Wilson and K. Wong and J. Wright and Z. Xia and X. Xu and D. Youchison and G. Yu and H. Yuh and L. Zakharov and D. Zemlyanov and S. Zweben",
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Gates, DA, Ahn, J, Allain, J, Andre, R, Bastasz, R, Bell, M, Bell, R, Belova, E, Berkery, J, Betti, R, Bialek, J, Biewer, T, Bigelow, T, Bitter, M, Boedo, J, Bonoli, P, Boozer, A, Brennan, D, Breslau, J, Brower, D, Bush, C, Canik, J, Caravelli, G, Carter, M, Caughman, J, Chang, C, Choe, W, Crocker, N, Darrow, D, Delgado-Aparicio, L, Diem, S, D'Ippolito, D, Domier, C, Dorland, W, Efthimion, P, Ejiri, A, Ershov, N, Evans, T, Feibush, E, Fenstermacher, M, Ferron, J, Finkenthal, M, Foley, J, Frazin, R, Fredrickson, E, Fu, G, Funaba, H, Gerhardt, S, Glasser, A, Gorelenkov, N, Grisham, L, Hahm, T, Harvey, R, Hassanein, A, Heidbrink, W, Hill, K, Hillesheim, J, Hillis, D, Hirooka, Y, Hosea, J, Hu, B, Humphreys, D, Idehara, T, Indireshkumar, K, Ishida, A, Jaeger, F, Jarboe, T, Jardin, S, Jaworski, M, Ji, H, Jung, H, Kaita, R, Kallman, J, Katsuro-Hopkins, O, Kawahata, K, Kawamori, E, Kaye, S, Kessel, C, Kim, J, Kimura, H, Kolemen, E, Krasheninnikov, S, Krstic, P, Ku, S, Kubota, S, Kugel, H, La Haye, R, Lao, L, Leblanc, B, Lee, W, Lee, K, Leuer, J, Levinton, F, Liang, Y, Liu, D, Luhmann, N, Maingi, R, Majeski, R, Manickam, J, Mansfield, D, Maqueda, R, Mazzucato, E, McCune, D, McGeehan, B, McKee, G, Medley, S, Menard, J, Menon, M, Meyer, H, Mikkelsen, D, Miloshevsky, G, Mitarai, O, Mueller, D, Mueller, S, Munsat, T, Myra, J, Nagayama, Y, Nelson, B, Nguyen, X, Nishino, N, Nishiura, M, Nygren, R, Ono, M, Osborne, T, Pacella, D, Park, H, Park, J, Paul, S, Peebles, W, Penaflor, B, Peng, M, Phillips, C, Pigarov, A, Podesta, M, Preinhaelter, J, Ram, A, Raman, R, Rasmussen, D, Redd, A, Reimerdes, H, Rewoldt, G, Ross, P, Rowley, C, Ruskov, E, Russell, D, Ruzic, D, Ryan, P, Sabbagh, S, Schaffer, M, Schuster, E, Scott, S, Shaing, K, Sharpe, P, Shevchenko, V, Shinohara, K, Sizyuk, V, Skinner, C, Smirnov, A, Smith, D, Smith, S, Snyder, P, Solomon, W, Sontag, A, Soukhanovskii, V, Stoltzfus-Dueck, T, Stotler, D, Strait, T, Stratton, B, Stutman, D, Takahashi, R, Takase, Y, Tamura, N, Tang, X, Taylor, G, Taylor, C, Ticos, C, Tritz, K, Tsarouhas, D, Turrnbull, A, Tynan, G, Ulrickson, M, Umansky, M, Urban, J, Utergberg, E, Walker, M, Wampler, W, Wang, J, Wang, W, Welander, A, Whaley, J, White, R, Wilgen, J, Wilson, R, Wong, K, Wright, J, Xia, Z, Xu, X, Youchison, D, Yu, G, Yuh, H, Zakharov, L, Zemlyanov, D & Zweben, S 2009, 'Overview of results from the national spherical torus experiment (NSTX)', Nuclear Fusion, vol. 49, no. 10, 104016. https://doi.org/10.1088/0029-5515/49/10/104016

Overview of results from the national spherical torus experiment (NSTX). / Gates, D. A.; Ahn, J.; Allain, J.; Andre, R.; Bastasz, R.; Bell, M.; Bell, R.; Belova, E.; Berkery, J.; Betti, R.; Bialek, J.; Biewer, T.; Bigelow, T.; Bitter, M.; Boedo, J.; Bonoli, P.; Boozer, A.; Brennan, D.; Breslau, J.; Brower, D.; Bush, C.; Canik, J.; Caravelli, G.; Carter, M.; Caughman, J.; Chang, C.; Choe, W.; Crocker, N.; Darrow, D.; Delgado-Aparicio, L.; Diem, S.; D'Ippolito, D.; Domier, C.; Dorland, W.; Efthimion, P.; Ejiri, A.; Ershov, N.; Evans, T.; Feibush, E.; Fenstermacher, M.; Ferron, J.; Finkenthal, M.; Foley, J.; Frazin, R.; Fredrickson, E.; Fu, G.; Funaba, H.; Gerhardt, S.; Glasser, A.; Gorelenkov, N.; Grisham, L.; Hahm, T.; Harvey, R.; Hassanein, A.; Heidbrink, W.; Hill, K.; Hillesheim, J.; Hillis, D.; Hirooka, Y.; Hosea, J.; Hu, B.; Humphreys, D.; Idehara, T.; Indireshkumar, K.; Ishida, A.; Jaeger, F.; Jarboe, T.; Jardin, S.; Jaworski, M.; Ji, H.; Jung, H.; Kaita, R.; Kallman, J.; Katsuro-Hopkins, O.; Kawahata, K.; Kawamori, E.; Kaye, S.; Kessel, C.; Kim, J.; Kimura, H.; Kolemen, E.; Krasheninnikov, S.; Krstic, P.; Ku, S.; Kubota, S.; Kugel, H.; La Haye, R.; Lao, L.; Leblanc, B.; Lee, W.; Lee, K.; Leuer, J.; Levinton, F.; Liang, Y.; Liu, D.; Luhmann, N.; Maingi, R.; Majeski, R.; Manickam, J.; Mansfield, D.; Maqueda, R.; Mazzucato, E.; McCune, D.; McGeehan, B.; McKee, G.; Medley, S.; Menard, J.; Menon, M.; Meyer, H.; Mikkelsen, D.; Miloshevsky, G.; Mitarai, O.; Mueller, D.; Mueller, S.; Munsat, T.; Myra, J.; Nagayama, Y.; Nelson, B.; Nguyen, X.; Nishino, N.; Nishiura, M.; Nygren, R.; Ono, M.; Osborne, T.; Pacella, D.; Park, H.; Park, J.; Paul, S.; Peebles, W.; Penaflor, B.; Peng, M.; Phillips, C.; Pigarov, A.; Podesta, M.; Preinhaelter, J.; Ram, A.; Raman, R.; Rasmussen, D.; Redd, A.; Reimerdes, H.; Rewoldt, G.; Ross, P.; Rowley, C.; Ruskov, E.; Russell, D.; Ruzic, D.; Ryan, P.; Sabbagh, S.; Schaffer, M.; Schuster, E.; Scott, S.; Shaing, K.; Sharpe, P.; Shevchenko, V.; Shinohara, K.; Sizyuk, V.; Skinner, C.; Smirnov, A.; Smith, D.; Smith, S.; Snyder, P.; Solomon, W.; Sontag, A.; Soukhanovskii, V.; Stoltzfus-Dueck, T.; Stotler, D.; Strait, T.; Stratton, B.; Stutman, D.; Takahashi, R.; Takase, Y.; Tamura, N.; Tang, X.; Taylor, G.; Taylor, C.; Ticos, C.; Tritz, K.; Tsarouhas, D.; Turrnbull, A.; Tynan, G.; Ulrickson, M.; Umansky, M.; Urban, J.; Utergberg, E.; Walker, M.; Wampler, W.; Wang, J.; Wang, W.; Welander, A.; Whaley, J.; White, R.; Wilgen, J.; Wilson, R.; Wong, K.; Wright, J.; Xia, Z.; Xu, X.; Youchison, D.; Yu, G.; Yuh, H.; Zakharov, L.; Zemlyanov, D.; Zweben, S.

In: Nuclear Fusion, Vol. 49, No. 10, 104016, 21.09.2009.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Overview of results from the national spherical torus experiment (NSTX)

AU - Gates, D. A.

AU - Ahn, J.

AU - Allain, J.

AU - Andre, R.

AU - Bastasz, R.

AU - Bell, M.

AU - Bell, R.

AU - Belova, E.

AU - Berkery, J.

AU - Betti, R.

AU - Bialek, J.

AU - Biewer, T.

AU - Bigelow, T.

AU - Bitter, M.

AU - Boedo, J.

AU - Bonoli, P.

AU - Boozer, A.

AU - Brennan, D.

AU - Breslau, J.

AU - Brower, D.

AU - Bush, C.

AU - Canik, J.

AU - Caravelli, G.

AU - Carter, M.

AU - Caughman, J.

AU - Chang, C.

AU - Choe, W.

AU - Crocker, N.

AU - Darrow, D.

AU - Delgado-Aparicio, L.

AU - Diem, S.

AU - D'Ippolito, D.

AU - Domier, C.

AU - Dorland, W.

AU - Efthimion, P.

AU - Ejiri, A.

AU - Ershov, N.

AU - Evans, T.

AU - Feibush, E.

AU - Fenstermacher, M.

AU - Ferron, J.

AU - Finkenthal, M.

AU - Foley, J.

AU - Frazin, R.

AU - Fredrickson, E.

AU - Fu, G.

AU - Funaba, H.

AU - Gerhardt, S.

AU - Glasser, A.

AU - Gorelenkov, N.

AU - Grisham, L.

AU - Hahm, T.

AU - Harvey, R.

AU - Hassanein, A.

AU - Heidbrink, W.

AU - Hill, K.

AU - Hillesheim, J.

AU - Hillis, D.

AU - Hirooka, Y.

AU - Hosea, J.

AU - Hu, B.

AU - Humphreys, D.

AU - Idehara, T.

AU - Indireshkumar, K.

AU - Ishida, A.

AU - Jaeger, F.

AU - Jarboe, T.

AU - Jardin, S.

AU - Jaworski, M.

AU - Ji, H.

AU - Jung, H.

AU - Kaita, R.

AU - Kallman, J.

AU - Katsuro-Hopkins, O.

AU - Kawahata, K.

AU - Kawamori, E.

AU - Kaye, S.

AU - Kessel, C.

AU - Kim, J.

AU - Kimura, H.

AU - Kolemen, E.

AU - Krasheninnikov, S.

AU - Krstic, P.

AU - Ku, S.

AU - Kubota, S.

AU - Kugel, H.

AU - La Haye, R.

AU - Lao, L.

AU - Leblanc, B.

AU - Lee, W.

AU - Lee, K.

AU - Leuer, J.

AU - Levinton, F.

AU - Liang, Y.

AU - Liu, D.

AU - Luhmann, N.

AU - Maingi, R.

AU - Majeski, R.

AU - Manickam, J.

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PY - 2009/9/21

Y1 - 2009/9/21

N2 - The mission of the National Spherical Torus Experiment (NSTX) is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high β operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale length. Results from n = 3 braking studies are consistent with the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of high harmonic fast-waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap current fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance li ∼ 0.4 with strong shaping (κ ∼ 2.7, δ ∼ 0.8) with βN approaching the with-wall β-limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction fNI ∼ 71%. Instabilities driven by super-Alfvénic ions will be an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfvénic. Linear toroidal Alfvén eigenmode thresholds and appreciable fast ion loss during multi-mode bursts are measured and these results are compared with theory. The impact of n > 1 error fields on stability is an important result for ITER. Resistive wall mode/resonant field amplification feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with β above the no-wall limit. Other highlights are results of lithium coating experiments, momentum confinement studies, scrape-off layer width scaling, demonstration of divertor heat load mitigation in strongly shaped plasmas and coupling of coaxial helicity injection plasmas to ohmic heating ramp-up. These results advance the ST towards next step fusion energy devices such as NHTX and ST-CTF.

AB - The mission of the National Spherical Torus Experiment (NSTX) is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high β operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale length. Results from n = 3 braking studies are consistent with the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of high harmonic fast-waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap current fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance li ∼ 0.4 with strong shaping (κ ∼ 2.7, δ ∼ 0.8) with βN approaching the with-wall β-limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction fNI ∼ 71%. Instabilities driven by super-Alfvénic ions will be an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfvénic. Linear toroidal Alfvén eigenmode thresholds and appreciable fast ion loss during multi-mode bursts are measured and these results are compared with theory. The impact of n > 1 error fields on stability is an important result for ITER. Resistive wall mode/resonant field amplification feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with β above the no-wall limit. Other highlights are results of lithium coating experiments, momentum confinement studies, scrape-off layer width scaling, demonstration of divertor heat load mitigation in strongly shaped plasmas and coupling of coaxial helicity injection plasmas to ohmic heating ramp-up. These results advance the ST towards next step fusion energy devices such as NHTX and ST-CTF.

UR - http://www.scopus.com/inward/record.url?scp=70349113512&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=70349113512&partnerID=8YFLogxK

U2 - 10.1088/0029-5515/49/10/104016

DO - 10.1088/0029-5515/49/10/104016

M3 - Article

AN - SCOPUS:70349113512

VL - 49

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 10

M1 - 104016

ER -