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301. Multitude of Core-Localized Shear Alfvén Waves in a High-Temperature Fusion Plasma

Author

Nazikian, R., primary, Berk, H. L., additional, Budny, R. V., additional, Burrell, K. H., additional, Doyle, E. J., additional, Fonck, R. J., additional, Gorelenkov, N. N., additional, Holcomb, C., additional, Kramer, G. J., additional, Jayakumar, R. J., additional, La Haye, R. J., additional, McKee, G. R., additional, Makowski, M. A., additional, Peebles, W. A., additional, Rhodes, T. L., additional, Solomon, W. M., additional, Strait, E. J., additional, VanZeeland, M. A., additional, and Zeng, L., additional

Published
2006
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302. Energetic ion transport by abrupt large-amplitude event induced by negative-ion-based neutral beam injection in the JT-60U

Author

Ishikawa, M, primary, Takechi, M, additional, Shinohara, K, additional, Kusama, Y, additional, Cheng, C.Z, additional, Matsunaga, G, additional, Todo, Y, additional, Gorelenkov, N.N, additional, Kramer, G.J, additional, Nazikian, R, additional, Fukuyama, A, additional, Krasilnikov, V.A, additional, Kashuck, Yu, additional, Nishitani, T, additional, Morioka, A, additional, Sasao, M, additional, Isobe, M, additional, and team, the JT-60, additional

Published
2005
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304. Experimental studies of instabilities and confinement of energetic particles on JET and MAST

Author

Sharapov, S.E, primary, Alper, B, additional, Andersson, F, additional, Baranov, Yu.F, additional, Berk, H.L, additional, Bertalot, L, additional, Borba, D, additional, Boswell, C, additional, Breizman, B.N, additional, Buttery, R, additional, Challis, C.D, additional, Baar, M. de, additional, Vries, P. de, additional, Eriksson, L.-G, additional, Fasoli, A, additional, Galvao, R, additional, Goloborod'ko, V, additional, Gryaznevich, M.P, additional, Hastie, R.J, additional, Hawkes, N.C, additional, Helander, P, additional, Kiptily, V.G, additional, Kramer, G.J, additional, Lomas, P.J, additional, Mailloux, J, additional, Mantsinen, M.J, additional, Martin, R, additional, Nabais, F, additional, Nave, M.F, additional, Nazikian, R, additional, Noterdaeme, J.-M, additional, Pekker, M.S, additional, Pinches, S.D, additional, Pinfold, T, additional, Popovichev, S.V, additional, Sandquist, P, additional, Stork, D, additional, Testa, D, additional, Tuccillo, A, additional, Voitsekhovich, I, additional, Yavorskij, V, additional, Young, N.P, additional, Zonca, F, additional, Contributors, JET-EFDA, additional, and Team, the MAST, additional

Published
2005
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308. Monitoring Alfvén Cascades with Interferometry on the JET Tokamak

Author

Sharapov, S. E., primary, Alper, B., additional, Fessey, J., additional, Hawkes, N. C., additional, Young, N. P., additional, Nazikian, R., additional, Kramer, G. J., additional, Borba, D. N., additional, Hacquin, S., additional, De La Luna, E., additional, Pinches, S. D., additional, Rapp, J., additional, Testa, D., additional, and Contributors, JET-EFDA, additional

Published
2004
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311. Energetic particle physics in JT-60U and JFT-2M

Author

Shinohara, K, primary, Takechi, M, additional, Ishikawa, M, additional, Kusama, Y, additional, Tsuzuki, K, additional, Urata, K, additional, Kawashima, H, additional, Tobita, K, additional, Fukuyama, A, additional, Cheng, C Z, additional, Darrow, D S, additional, Kramer, G J, additional, Gorelenkov, N N, additional, Nazikian, R, additional, Todo, Y, additional, Miura, Y, additional, and Ozeki, T, additional

Published
2004
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314. Overview of recent Alcator C-Mod research

Author

Marmar, E.S, primary, Bai, B, additional, Boivin, R.L, additional, Bonoli, P.T, additional, Boswell, C, additional, Bravenec, R, additional, Carreras, B, additional, Ernst, D, additional, Fiore, C, additional, Gangadhara, S, additional, Gentle, K, additional, Goetz, J, additional, Granetz, R, additional, Greenwald, M, additional, Hallatschek, K, additional, Hastie, J, additional, Hosea, J, additional, Hubbard, A, additional, Hughes, J.W, additional, Hutchinson, I, additional, In, Y, additional, Irby, J, additional, Jennings, T, additional, Kopon, D, additional, Kramer, G, additional, LaBombard, B, additional, Lee, W.D, additional, Lin, Y, additional, Lipschultz, B, additional, Liptac, J, additional, Lynn, A, additional, Marr, K, additional, Maqueda, R, additional, Melby, E, additional, Mikkelsen, D, additional, Mossessian, D, additional, Nazikian, R, additional, Nevins, W.M, additional, Parker, R, additional, Pedersen, T.S, additional, Phillips, C.K, additional, Phillips, P, additional, Pitcher, C.S, additional, Porkolab, M, additional, Ramos, J, additional, Redi, M, additional, Rice, J, additional, Rogers, B.N, additional, Rowan, W.L, additional, Sampsell, M, additional, Schilling, G, additional, Scott, S, additional, Snipes, J, additional, Snyder, P, additional, Stotler, D, additional, Taylor, G, additional, Terry, J.L, additional, Wilson, H, additional, Wilson, J.R, additional, Wolfe, S.M, additional, Wukitch, S, additional, Xu, X.Q, additional, Youngblood, B, additional, Yuh, H, additional, Zhurovich, K, additional, and Zweben, S, additional

Published
2003
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315. Relationship between particle and heat transport in JT-60U plasmas with internal transport barrier

Author

Takenaga, H, primary, Higashijima, S, additional, Oyama, N, additional, Bruskin, L.G, additional, Koide, Y, additional, Ide, S, additional, Shirai, H, additional, Sakamoto, Y, additional, Suzuki, T, additional, Hill, K.W, additional, Rewoldt, G, additional, Kramer, G.J, additional, Nazikian, R, additional, Takizuka, T, additional, Fujita, T, additional, Sakasai, A, additional, Kamada, Y, additional, Kubo, H, additional, and Team, the JT-60, additional

Published
2003
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318. Alpha-particle physics in the tokamak fusion test reactor DT experiment

Author

Zweben, SJ, Zweben, SJ, Arunasalam, V, Batha, SH, Budny, RV, Bush, CE, Cauffman, S, Chang, CS, Chang, Z, Cheng, CZ, Darrow, DS, Dendy, RO, Duong, HH, Fisch, NJ, Fredrickson, ED, Fisher, RK, Fonck, RJ, Fu, GY, Goloborod'ko, V, Gorelenkov, N, Hawryluk, RJ, Heeter, R, Heidbrink, WW, Hermann, HW, Hermann, M, Johnson, DW, Machuzak, J, Majeski, R, McGuire, KM, McKee, G, Medley, SS, Mynick, HE, Nazikian, R, Petrov, MP, Redi, MH, Reznik, S, Rogers, J, Schilling, G, Spong, DA, Strachan, JD, Stratton, BC, Synakowski, E, Taylor, G, Wang, S, White, RB, Wong, KL, Yavorski, V, Zweben, SJ, Zweben, SJ, Arunasalam, V, Batha, SH, Budny, RV, Bush, CE, Cauffman, S, Chang, CS, Chang, Z, Cheng, CZ, Darrow, DS, Dendy, RO, Duong, HH, Fisch, NJ, Fredrickson, ED, Fisher, RK, Fonck, RJ, Fu, GY, Goloborod'ko, V, Gorelenkov, N, Hawryluk, RJ, Heeter, R, Heidbrink, WW, Hermann, HW, Hermann, M, Johnson, DW, Machuzak, J, Majeski, R, McGuire, KM, McKee, G, Medley, SS, Mynick, HE, Nazikian, R, Petrov, MP, Redi, MH, Reznik, S, Rogers, J, Schilling, G, Spong, DA, Strachan, JD, Stratton, BC, Synakowski, E, Taylor, G, Wang, S, White, RB, Wong, KL, and Yavorski, V

Abstract

A summary is presented of recent alpha-particle experiments on the tokamak fusion test reactor. Alpha particles are generally well confined in MHD-quiescent discharges, and alpha heating of electrons has been observed. The theoretically predicted toroidicity-induced Alfvén eigenmode has been seen in discharges of ≤ 1 MW of alpha power, but only in plasmas with weak magnetic shear. © 1997 IOP Publishing Ltd.

Published
1997

319. Deuterium–tritium plasmas in novel regimes in the Tokamak Fusion Test Reactor

Author

Bell, MG, Bell, MG, Batha, S, Beer, M, Bell, RE, Belov, A, Berk, H, Bernabei, S, Bitter, M, Breizman, B, Bretz, NL, Budny, R, Bush, CE, Callen, J, Cauffman, S, Chang, CS, Chang, Z, Cheng, CZ, Darrow, DS, Dendy, RO, Dorland, W, Duong, H, Efthimion, PC, Ernst, D, Evenson, H, Fisch, NJ, Fisher, R, Fonck, RJ, Fredrickson, ED, fu, GY, Furth, HP, Gorelenkov, NN, Goloborod’ko, VY, Grek, B, Grisham, LR, Hammett, GW, Hawryluk, RJ, Heidbrink, W, Herrmann, HW, Herrmann, MC, Hill, KW, Hogan, J, Hooper, B, Hosea, JC, Houlberg, WA, Hughes, M, Jassby, DL, Jobes, FC, Johnson, DW, Kaita, R, Kaye, S, Kesner, J, Kim, JS, Kissick, M, Krasilnikov, AV, Kugel, H, Kumar, A, Lam, NT, Lamarche, P, Leblanc, B, Levinton, FM, Ludescher, C, Machuzak, J, Majeski, RP, Manickam, J, Mansfield, DK, Mauel, M, Mazzucato, E, Mcchesney, J, Mccune, DC, Mckee, G, Mcguire, KM, Meade, DM, Medley, SS, Mikkelsen, DR, Mirnov, SV, Mueller, D, Nagayama, Y, Navratil, GA, Nazikian, R, Okabayashi, M, Osakabe, M, Owens, DK, Park, HK, Park, W, Paul, SF, Petrov, MP, Phillips, CK, Phillips, M, Phillips, P, Ramsey, AT, Rice, B, Redi, MH, Rewoldt, G, Reznik, S, Roquemore, AL, Rogers, J, Ruskov, E, Sabbagh, SA, Sasao, M, Schilling, G, Bell, MG, Bell, MG, Batha, S, Beer, M, Bell, RE, Belov, A, Berk, H, Bernabei, S, Bitter, M, Breizman, B, Bretz, NL, Budny, R, Bush, CE, Callen, J, Cauffman, S, Chang, CS, Chang, Z, Cheng, CZ, Darrow, DS, Dendy, RO, Dorland, W, Duong, H, Efthimion, PC, Ernst, D, Evenson, H, Fisch, NJ, Fisher, R, Fonck, RJ, Fredrickson, ED, fu, GY, Furth, HP, Gorelenkov, NN, Goloborod’ko, VY, Grek, B, Grisham, LR, Hammett, GW, Hawryluk, RJ, Heidbrink, W, Herrmann, HW, Herrmann, MC, Hill, KW, Hogan, J, Hooper, B, Hosea, JC, Houlberg, WA, Hughes, M, Jassby, DL, Jobes, FC, Johnson, DW, Kaita, R, Kaye, S, Kesner, J, Kim, JS, Kissick, M, Krasilnikov, AV, Kugel, H, Kumar, A, Lam, NT, Lamarche, P, Leblanc, B, Levinton, FM, Ludescher, C, Machuzak, J, Majeski, RP, Manickam, J, Mansfield, DK, Mauel, M, Mazzucato, E, Mcchesney, J, Mccune, DC, Mckee, G, Mcguire, KM, Meade, DM, Medley, SS, Mikkelsen, DR, Mirnov, SV, Mueller, D, Nagayama, Y, Navratil, GA, Nazikian, R, Okabayashi, M, Osakabe, M, Owens, DK, Park, HK, Park, W, Paul, SF, Petrov, MP, Phillips, CK, Phillips, M, Phillips, P, Ramsey, AT, Rice, B, Redi, MH, Rewoldt, G, Reznik, S, Roquemore, AL, Rogers, J, Ruskov, E, Sabbagh, SA, Sasao, M, and Schilling, G

Abstract

Experiments in the Tokamak Fusion Test Reactor (TFTR) [Phys. Plasmas 2, 2176 (1995)] have explored several novel regimes of improved tokamak confinement in deuterium–tritium (D–T) plasmas, including plasmas with reduced or reversed magnetic shear in the core and high-current plasmas with increased shear in the outer region (high [formula omitted]). New techniques have also been developed to enhance the confinement in these regimes by modifying the plasma-limiter interaction through in situ deposition of lithium. In reversed-shear plasmas, transitions to enhanced confinement have been observed at plasma currents up to 2.2 MA [formula omitted] accompanied by the formation of internal transport barriers, where large radial gradients develop in the temperature and density profiles. Experiments have been performed to elucidate the mechanism of the barrier formation and its relationship with the magnetic configuration and with the heating characteristics. The increased stability of high-current, high-[formula omitted] plasmas produced by rapid expansion of the minor cross section, coupled with improvement in the confinement by lithium deposition has enabled the achievement of high fusion power, up to 8.7 MW, with D–T neutral beam heating. The physics of fusion alpha-particle confinement has been investigated in these regimes, including the interactions of the alphas with endogenous plasma instabilities and externally applied waves in the ion cyclotron range of frequencies. In D–T plasmas with [formula omitted] and weak magnetic shear in the central region, a toroidal Alfvén eigenmode instability driven purely by the alpha particles has been observed for the first time. The interactions of energetic ions with ion Bernstein waves produced by mode conversion from fast waves in mixed-species plasmas have been studied as a possible mechanism for transferring the energy of the alphas to fuel ions. © 1997, American Institute of Physics. All rights reserved.

Published
1997

320. 3D Full-Wave Simulations of Reflectometry.

Author

Valeo, E. J., Kramer, G. J., and Nazikian, R.

Subjects
WAVE mechanics, TOROIDAL harmonics, SIMULATION methods & models, STATISTICAL correlation, HARMONIC analysis (Mathematics)
Abstract

The characterization of fluctuation amplitudes, spatial correlation lengths, and wave vectors through measurement of the correlation properties of reflected microwave diagnostic signals depends on a quantitaive knowledge of propagation in toroidal, magnetized plasma. The disparity between the radiation wavelength (mm) and the plasma size makes full wave computations challenging. We extend a two dimensional model [1] which computes propagation in a poloidal plane to include toroidal variation. The model reduces the computational burden compared to that of solving the full-wave equation everywhere-but retains both diffraction and refraction-by merging a description appropriate to the under dense plasma (paraxial) with the required full-wave description near the reflection layer. Initial results for ITER-like profiles demonstrate the utility of the tool as an aid in specifying antenna positioning and setting sensitivity requirements. [ABSTRACT FROM AUTHOR]

Published
2009
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326. Overview of recent Alcator C-Mod results

Author

Hutchinson, I.H., primary, Boivin, R., additional, Bonoli, P.T., additional, Boswell, C., additional, Bravenec, R., additional, Bretz, N.L., additional, Chatterjee, R., additional, Chung, T., additional, Eisner, E., additional, Fiore, C., additional, Gangadhara, S., additional, Gentle, K., additional, Goetz, J.A., additional, Granetz, R.S., additional, Greenwald, M.J., additional, Hosea, J.C., additional, Hubbard, A.E., additional, Hughes, J., additional, In, Y., additional, Irby, J., additional, LaBombard, B., additional, Lin, Y., additional, Lipschultz, B., additional, Maqueda, R.J., additional, Marmar, E.S., additional, Mazurenko, A., additional, Mikkelsen, D., additional, Mossessian, D., additional, Nachtrieb, R., additional, Nazikian, R., additional, Nelson-Melby, E., additional, Pappas, D., additional, Parker, R.R., additional, Pedersen, T. Sunn, additional, Phillips, P., additional, Pitcher, C.S., additional, Porkolab, M., additional, Rice, J.E., additional, Rowan, W., additional, Schilling, G., additional, Snipes, J.A., additional, Taylor, G., additional, Terry, J.L., additional, Wilson, J.R., additional, Wolfe, S.M., additional, Wukitch, S.J., additional, Yuh, H., additional, Zweben, S.J., additional, Acedo, P., additional, Brambilla, M., additional, Carreras, B.A., additional, Gandy, R., additional, Hallock, G.A., additional, Dorland, W., additional, Johnson, D., additional, Krashennikova, N., additional, Phillips, C., additional, Tutt, T., additional, Watts, C., additional, and Umansky, M., additional

Published
2001
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328. Alfvén eigenmodes driven by Alfvénic beam ions in JT-60U

Author

Shinohara, K, primary, Kusama, Y, additional, Takechi, M, additional, Morioka, A, additional, Ishikawa, M, additional, Oyama, N, additional, Tobita, K, additional, Ozeki, T, additional, Takeji, S, additional, Moriyama, S, additional, Fujita, T, additional, Oikawa, T, additional, Suzuki, T, additional, Nishitani, T, additional, Kondoh, T, additional, Lee, S, additional, Kuriyama, M, additional, Team, JT-60, additional, Kramer, G.J, additional, Gorelenkov, N.N, additional, Nazikian, R, additional, Cheng, C.Z, additional, Fu, G.Y, additional, and Fukuyama, A, additional

Published
2001
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333. Fast particle experiments in JT-60U

Author

Kramer, G.J, primary, Iwase, M, additional, Kusama, Y, additional, Morioka, A, additional, Nemoto, M, additional, Nishitani, T, additional, Shinohara, K, additional, Takeji, S, additional, Tobita, K, additional, Ozeki, T, additional, Cheng, C.Z, additional, Fu, G.-Y, additional, and Nazikian, R, additional

Published
2000
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335. Measurements and scalings of the H-mode pedestal on Alcator C-Mod

Author

Mossessian, D, primary, Hubbard, A E, additional, Marmar, E S, additional, Pedersen, T Sunn, additional, Granetz, R S, additional, Boivin, R L, additional, Greenwald, M, additional, Hughes, J, additional, Irby, J, additional, Johnson, D, additional, LaBombard, B, additional, Lin, Y, additional, Mazurenko, A, additional, Nazikian, R, additional, Pitcher, C S, additional, Taylor, G, additional, Mossessian, D, additional, and Wolfe, S M, additional

Published
2000
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336. ICRF heating and profile control techniques in TFTR

Author

Phillips, C.K, primary, Bell, M.G, additional, Bell, R.E, additional, Bernabei, S, additional, Bettenhausen, M, additional, Bush, C.E, additional, Clark, D, additional, Darrow, D.S, additional, Fredrickson, E.D, additional, Hanson, G.R, additional, Hosea, J.C, additional, LeBlanc, B.P, additional, Majeski, R.P, additional, Medley, S.S, additional, Nazikian, R, additional, Ono, M, additional, Park, H.K, additional, Petrov, M.P, additional, Rogers, J.H, additional, Schilling, G, additional, Skinner, C.H, additional, Smithe, D.N, additional, Synakowski, E.J, additional, Taylor, G, additional, and Wilson, J.R, additional

Published
2000
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338. Deuterium and tritium experiments on TFTR

Author

Strachan, JD, Strachan, JD, Adler, H, Barnes, CW, Batha, S, Bell, MG, Bell, R, Bitter, M, Bretz, NL, Budny, R, Bush, CE, Caorlin, M, Chang, Z, Darrow, DS, Duong, H, Durst, R, Efthimion, PC, Fisher, R, Fonck, RJ, Fredrickson, E, Grek, B, Grisham, LR, Hammett, G, Hawryiuk, RJ, Heidbrink, W, Herrmann, HW, Hill, KW, Hosea, J, Hsuan, H, Janos, A, Jassby, DL, Jobes, FC, Johnson, DW, Johnson, LC, Kugel, H, Lam, NT, LeBlanc, B, Levington, FM, Machuzak, J, Mansfield, DK, Mazzucato, E, Majeski, R, Marmar, E, McChesney, J, McGuire, KM, McKee, G, Meade, DM, Medley, SS, Mikkelsen, DR, Mueller, D, Murakami, M, Nazikian, R, Osakabe, M, Owens, DK, Park, H, Paul, SF, Petrov, M, Phillips, CK, Ramsey, AT, Redi, MH, Roberts, D, Rogers, J, Roquemore, AL, Ruskov, E, Sabbagh, SA, Sasao, M, Schilling, G, Schivell, J, Schmidt, GL, Scott, SD, Skinner, CH, Snipes, JA, Stevens, J, Stevenson, T, Stratton, BC, Synakowski, E, Taylor, G, Terry, JL, Von Halle, A, Von Goeler, S, Wilgen, JB, Wilson, JR, Wong, KL, Wurden, GA, Yamada, M, Young, KM, Zarnstorff, MC, Zweben, SJ, Strachan, JD, Strachan, JD, Adler, H, Barnes, CW, Batha, S, Bell, MG, Bell, R, Bitter, M, Bretz, NL, Budny, R, Bush, CE, Caorlin, M, Chang, Z, Darrow, DS, Duong, H, Durst, R, Efthimion, PC, Fisher, R, Fonck, RJ, Fredrickson, E, Grek, B, Grisham, LR, Hammett, G, Hawryiuk, RJ, Heidbrink, W, Herrmann, HW, Hill, KW, Hosea, J, Hsuan, H, Janos, A, Jassby, DL, Jobes, FC, Johnson, DW, Johnson, LC, Kugel, H, Lam, NT, LeBlanc, B, Levington, FM, Machuzak, J, Mansfield, DK, Mazzucato, E, Majeski, R, Marmar, E, McChesney, J, McGuire, KM, McKee, G, Meade, DM, Medley, SS, Mikkelsen, DR, Mueller, D, Murakami, M, Nazikian, R, Osakabe, M, Owens, DK, Park, H, Paul, SF, Petrov, M, Phillips, CK, Ramsey, AT, Redi, MH, Roberts, D, Rogers, J, Roquemore, AL, Ruskov, E, Sabbagh, SA, Sasao, M, Schilling, G, Schivell, J, Schmidt, GL, Scott, SD, Skinner, CH, Snipes, JA, Stevens, J, Stevenson, T, Stratton, BC, Synakowski, E, Taylor, G, Terry, JL, Von Halle, A, Von Goeler, S, Wilgen, JB, Wilson, JR, Wong, KL, Wurden, GA, Yamada, M, Young, KM, Zarnstorff, MC, and Zweben, SJ

Abstract

Three campaigns, prior to July 1994, attempted to increase the fusion power in DT plasmas on the Tokamak Fusion Test Reactor (TFTR). The first campaign was dedicated to obtaining >5 MW of fusion power while avoiding MHD events similar to the JET X-event. The second was aimed at producing maximum fusion power irrespective of proximity to MHD limits, and achieved 9 MW limited by a disruption. The third campaign increased the energy confinement time using lithium pellet conditioning while raising the ratio of alpha heating to beam heating.

Published
1994

339. Using neutral beams as a light ion beam probe (invited).

Author

Xi Chen, Heidbrink, W. W., Van Zeeland, M. A., Kramer, G. J., Pace, D. C., Petty, C. C., Austin, M. E., Fisher, R. K., Hanson, J. M., Nazikian, R., and Zeng, L.

Subjects
NEUTRAL beams, ION beams, DETECTORS, FAST ions, PARTICLES, PLASMA core reactors
Abstract

By arranging the particle first banana orbits to pass near a distant detector, the light ion beam probe (LIBP) utilizes orbital deflection to probe internal fields and field fluctuations. The LIBP technique takes advantage of (1) the in situ, known source of fast ions created by beam-injected neutral particles that naturally ionize near the plasma edge and (2) various commonly available diagnostics as its detector. These born trapped particles can traverse the plasma core on their inner banana leg before returning to the plasma edge. Orbital displacements (the forces on fast ions) caused by internal instabilities or edge perturbing fields appear as modulated signal at an edge detector. Adjustments in the q-profile and plasma shape that determine the first orbit, as well as the relative position of the source and detector, enable studies under a wide variety of plasma conditions. This diagnostic technique can be used to probe the impact on fast ions of various instabilities, e.g., Alfvén eigenmodes (AEs) and neoclassical tearing modes, and of externally imposed 3D fields, e.g., magnetic perturbations. To date, displacements by AEs and by externally applied resonant magnetic perturbation fields have been measured using a fast ion loss detector. Comparisons with simulations are shown. In addition, nonlinear interactions between fast ions and independent AE waves are revealed by this technique. [ABSTRACT FROM AUTHOR]

Published
2014
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340. Enhanced localized energetic ion losses resulting from first-orbit linear and non-linear interactions with Alfvén eigenmodes in DIII-D.

Author

Chen, X., Heidbrink, W. W., Kramer, G. J., Van Zeeland, M. A., Pace, D. C., Petty, C. C., Fisher, R. K., Nazikian, R., Zeng, L., Austin, M. E., Grierson, B. A., and Podesta, M.

Subjects
LINEAR systems, NONLINEAR theories, PLASMA Alfven waves, NEUTRAL beams, HARMONIC oscillators
Abstract

Two key insights into interactions between Alfven eigenmodes (AEs) and energetic particles in the plasma core are gained from measurements and modeling of first-orbit beam-ion loss in DIII-D. First, the neutral beam-ion first-orbit losses are enhanced by AEs and a single AE can cause large fast-ion displacement. The coherent losses are from born trapped full energy beam-ions being non-resonantly scattered by AEs onto loss orbits within their first poloidal transit. The loss amplitudes scale linearly with the mode amplitude but the slope is different for different modes. The radial displacement of fast-ions by individual AEs can be directly inferred from the measurements. Second, oscillations in the beam-ion first-orbit losses are observed at the sum, difference, and harmonic frequencies of two independent AEs. These oscillations are not plasma modes and are absent in magnetic, density, and temperature fluctuations. The origin of the non-linearity as a wave-particle coupling is confirmed through bi-coherence analysis, which is clearly observed because the coherences are preserved by the first-orbit loss mechanism. An analytic model and full orbit simulations show that the non-linear features seen in the loss signal can be explained by a non-linear interaction between the fast ions and the two independent AEs. [ABSTRACT FROM AUTHOR]

Published
2014
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341. Linear ideal MHD predictions for n = 2 non-axisymmetric magnetic perturbations on DIII-D.

Author

Haskey, S R, Lanctot, M J, Liu, Y Q, Hanson, J M, Blackwell, B D, and Nazikian, R

Subjects
MAGNETIC resonance, MAGNETOHYDRODYNAMICS, TOKAMAKS, TOROIDAL plasma, MAGNETIC flux
Abstract

An extensive examination of the plasma response to dominantly n = 2 non-axisymmetric magnetic perturbations (MPs) on the DIII-D tokamak shows the potential to control 3D field interactions by varying the poloidal spectrum of the radial magnetic field. The plasma response is calculated as a function of the applied magnetic field structure and plasma parameters, using the linear magnetohydrodynamic code MARS-F (Liu et al 2000 Phys. Plasmas7 3681). The ideal, single fluid plasma response is decomposed into two main components: a local pitch-resonant response occurring at rational magnetic flux surfaces, and a global kink response. The efficiency with which the field couples to the total plasma response is determined by the safety factor and the structure of the applied field. In many cases, control of the applied field has a more significant effect than control of plasma parameters, which is of particular interest since it can be modified at will throughout a shot to achieve a desired effect. The presence of toroidal harmonics, other than the dominant n = 2 component, is examined revealing a significant n = 4 component in the perturbations applied by the DIII-D MP coils; however, modeling shows the plasma responses to n = 4 perturbations are substantially smaller than the dominant n = 2 responses in most situations. [ABSTRACT FROM AUTHOR]

Published
2014
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342. Modulation of prompt fast-ion loss by applied n = 2 fields in the DIII-D tokamak.

Author

Zeeland, M A Van, Ferraro, N M, Heidbrink, W W, Kramer, G J, Pace, D C, Chen, X, Evans, T E, Fisher, R K, García-Muñoz, M, Hanson, J M, Lanctot, M J, Lao, L L, Moyer, R A, Nazikian, R, and Orlov, D M

Subjects
ELECTRONIC modulation, TOKAMAKS testing, NEUTRAL beams, SYNCHROTRON radiation, ELECTROMAGNETIC measurements, SPHEROMAKS
Abstract

Energy and pitch angle resolved measurements of escaping neutral beam ions (E ≈ 80 keV) have been made during DIII-D L-mode discharges with applied, slowly rotating, n = 2 magnetic perturbations. Data from separate scintillator detectors (FILDs) near and well below the plasma midplane show fast-ion losses correlated with the internal coil (I-coil) fields. The dominant fast-ion loss signals are observed to decay within one poloidal transit time after beam turn-off indicating they are primarily prompt loss orbits. Also, during application of the rotating I-coil fields, outboard midplane edge density and bremsstrahlung emission profiles exhibit a radial displacement of up to δR ≈ 1 cm. Beam deposition and full orbit modeling of these losses using M3D-C1 calculations of the perturbed kinetic profiles and fields reproduce many features of the measured losses. In particular, the predicted phase of the modulated loss signal with respect to the I-coil currents is in close agreement with FILD measurements as is the relative amplitudes of the modulated losses for the co and counter-current beam used in the experiment. These simulations show modifications to the beam ion birth profile and subsequent prompt loss due to changes in the edge density; however, the dominant factor causing modulation of the losses to the fast-ion loss detectors is the perturbed magnetic field (δB/B ≈ 10−3 in the plasma). Calculations indicate total prompt loss to the DIII-D wall can increase with application of the n = 2 perturbation by up to 7% for co-current injected beams and 3% for counter-current injected beams depending on phase of the perturbation relative to the injected beam. [ABSTRACT FROM AUTHOR]

Published
2014
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344. Characteristics of Alfvén eigenmodes, burst modes and chirping modes in the Alfvén frequency range driven by negative ion based neutral beam injection in JT-60U

Author

Kusama, Y, primary, Kramer, G.J, additional, Kimura, H, additional, Saigusa, M, additional, Ozeki, T, additional, Tobita, K, additional, Oikawa, T, additional, Shinohara, K, additional, Kondoh, T, additional, Moriyama, M, additional, Tchernychev, F.V, additional, Nemoto, M, additional, Morioka, A, additional, Iwase, M, additional, Isei, N, additional, Fujita, T, additional, Takeji, S, additional, Kuriyama, M, additional, Nazikian, R, additional, Fu, G.Y, additional, Hill, K.W, additional, and Cheng, C.Z, additional

Published
1999
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346. Energetic particle transport and alpha driven instabilities in advanced confinement DT plasmas on TFTR

Author

Stratton, B.C, primary, Budny, R.V, additional, Darrow, D.S, additional, Fisher, R.K, additional, Fredrickson, E.D, additional, Fu, G.Y, additional, Medley, S.S, additional, Nazikian, R, additional, Petrov, M.P, additional, Redi, M.H, additional, Ruskov, E, additional, Taylor, G, additional, White, R.B, additional, Zweben, S.J, additional, and Group, TFTR, additional

Published
1999
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348. Role of Alfvén instabilities in energetic ion transport

Author

Bernabei, S., primary, Bell, M. G., additional, Budny, R., additional, Darrow, D., additional, Fredrickson, E. D., additional, Gorelenkov, N., additional, Hosea, J. C., additional, Majeski, R., additional, Mazzucato, E., additional, Nazikian, R., additional, Phillips, C. K., additional, Rogers, J. H., additional, Schilling, G., additional, White, R., additional, Wilson, J. R., additional, Zonca, F., additional, and Zweben, S., additional

Published
1999
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