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3. Overview of recent physics results from the National Spherical Torus Experiment (NSTX)

Author

Menard, JE, Bell, MG, Bell, RE, Bernabei, S, Bialek, J, Biewer, T, Blanchard, W, Boedo, J, Bush, CE, Carter, MD, Choe, W, Crocker, NA, Darrow, DS, Davis, W, Delgado-Aparicio, L, Diem, S, Domier, CW, D'Ippolito, DA, Ferron, J, Field, A, Foley, J, Fredrickson, ED, Gates, DA, Gibney, T, Harvey, R, Hatcher, RE, Heidbrink, W, Hill, KW, Hosea, JC, Jarboe, TR, Johnson, DW, Kaita, R, Kaye, SM, Kessel, CE, Kubota, S, Kugel, HW, Lawson, J, Leblanc, BP, Lee, KC, Levinton, FM, Luhmann, NC, Maingi, R, Majeski, RP, Manickam, J, Mansfield, DK, Maqueda, R, Marsala, R, Mastrovito, D, Mau, TK, Mazzucato, E, Medley, SS, Meyer, H, Mikkelsen, DR, Mueller, D, Munsat, T, Myra, JR, Nelson, BA, Neumeyer, C, Nishino, N, Ono, M, Park, HK, Park, W, Paul, SF, Peebles, T, Peng, M, Phillips, C, Pigarov, A, Pinsker, R, Ram, A, Ramakrishnan, S, Raman, R, Rasmussen, D, Redi, M, Rensink, M, Rewoldt, G, Robinson, J, Roney, P, Roquemore, AL, Ruskov, E, Ryan, P, Sabbagh, SA, Schneider, H, Skinner, CH, Smith, DR, Sontag, A, Soukhanovskii, V, Stevenson, T, Stotler, D, Stratton, BC, Stutman, D, Swain, D, Synakowski, E, Takase, Y, Taylor, G, Tritz, K, Von Halle, A, Wade, M, White, R, Wilgen, J, and Williams, M

Subjects
Physics::Plasma Physics
Abstract

The National Spherical Torus Experiment (NSTX) has made considerable progress in advancing the scientific understanding of high performance long-pulse plasmas needed for future spherical torus (ST) devices and ITER. Plasma durations up to 1.6 s (five current redistribution times) have been achieved at plasma currents of 0.7 MA with non-inductive current fractions above 65% while simultaneously achieving βT and βN values of 17% and 5.7 (%m T MA-1), respectively. A newly available motional Stark effect diagnostic has enabled validation of current-drive sources and improved the understanding of NSTX 'hybrid'-like scenarios. In MHD research, ex-vessel radial field coils have been utilized to infer and correct intrinsic EFs, provide rotation control and actively stabilize the n ≤ 1 resistive wall mode at ITER-relevant low plasma rotation values. In transport and turbulence research, the low aspect ratio and a wide range of achievable β in the NSTX provide unique data for confinement scaling studies, and a new microwave scattering diagnostic is being used to investigate turbulent density fluctuations with wavenumbers extending from ion to electron gyro-scales. In energetic particle research, cyclic neutron rate drops have been associated with the destabilization of multiple large toroidal Alfven eigenmodes (TAEs) analogous to the 'sea-of-TAE' modes predicted for ITER, and three-wave coupling processes have been observed for the first time. In boundary physics research, advanced shape control has enabled studies of the role of magnetic balance in H-mode access and edge localized mode stability. Peak divertor heat flux has been reduced by a factor of 5 using an H-mode-compatible radiative divertor, and lithium conditioning has demonstrated particle pumping and results in improved thermal confinement. Finally, non-solenoidal plasma start-up experiments have achieved plasma currents of 160 kA on closed magnetic flux surfaces utilizing coaxial helicity injection. © 2007 IAEA.

Published
2007
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4. The national spherical torus experiment (NSTX) research programme and progress towards high beta, long pulse operating scenarios

Author

Synakowski, EJ, Bell, MG, Bell, RE, Bigelow, T, Bitter, M, Blanchard, W, Boedo, J, Bourdelle, C, Bush, C, Darrow, DS, Efthimion, PC, Fredrickson, ED, Gates, DA, Gilmore, M, Grisham, LR, Hosea, JC, Johnson, DW, Kaita, R, Kaye, SM, Kubota, S, Kugel, HW, LeBlanc, BP, Lee, K, Maingi, R, Manickam, J, Maqueda, R, Mazzucato, E, Medley, SS, Menard, J, Mueller, D, Nelson, BA, Neumeyer, C, Ono, M, Paoletti, F, Park, HK, Paul, SF, Peng, YKM, Phillips, CK, Ramakrishnan, S, Raman, R, Roquemore, AL, Rosenberg, A, Ryan, PM, Sabbagh, SA, Skinner, CH, Soukhanovskii, V, Stevenson, T, Stutman, D, Swain, DW, Taylor, G, von Halle, A, Wilgen, J, Williams, M, Wilson, JR, Zweben, SJ, Akers, R, Barry, RE, Beiersdorfer, P, Bialek, JM, Blagojevic, B, Bonoli, PT, Budny, R, Carter, MD, Chang, CS, Chrzanowski, J, Davis, W, Deng, B, Doyle, EJ, Dudek, L, Egedal, J, Ellis, R, Ferron, JR, Finkenthal, M, Foley, J, Fredd, E, Glasser, A, Gibney, T, Goldston, RJ, Harvey, R, Hatcher, RE, Hawryluk, RJ, Heidbrink, W, Hill, KW, Houlberg, W, Jarboe, TR, Jardin, SC, Ji, H, Kalish, M, Lawrance, J, Lao, LL, Lee, KC, Levinton, FM, Luhmann, NC, Majeski, R, Marsala, R, Mastravito, D, Mau, TK, McCormack, B, Menon, MM, and Mitarai, O

Subjects
Physics::Plasma Physics
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 βT ≡ /(BT02/2μ0) 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 is 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 comparison 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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5. Progress towards high-performance, steady-state spherical torus

Author

Ono, M, Bell, MG, Bell, RE, Bigelow, T, Bitter, M, Blanchard, W, Boedo, J, Bourdelle, C, Bush, C, Choe, W, Chrzanowski, J, Darrow, DS, Diem, SJ, Doerner, R, Efthimion, PC, Ferron, JR, Fonck, RJ, Fredrickson, ED, Garstka, GD, Gates, DA, Gray, T, Grisham, LR, Heidbrink, W, Hill, KW, Hoffman, D, Jarboe, TR, Johnson, DW, Kaita, R, Kaye, SM, Kessel, C, Kim, JH, Kissick, MW, Kubota, S, Kugel, HW, LeBlanc, BP, Lee, K, Lee, SG, Lewicki, BT, Luckhardt, S, Maingi, R, Majeski, R, Manickam, J, Maqueda, R, Mau, TK, Mazzucato, E, Medley, SS, Menard, J, Mueller, D, Nelson, BA, Neumeyer, C, Nishino, N, Ostrander, CN, Pacella, D, Paoletti, F, Park, HK, Park, W, Paul, SF, Peng, YKM, Phillips, CK, Pinsker, R, Probert, PH, Ramakrishnan, S, Raman, R, Redi, M, Roquemore, AL, Rosenberg, A, Ryan, PM, Sabbagh, SA, Schaffer, M, Schooff, RJ, Seraydarian, R, Skinner, CH, Sontag, AC, Soukhanovskii, V, Spaleta, J, Stevenson, T, Stutman, D, Swain, DW, Synakowski, E, Takase, Y, Tang, X, Taylor, G, Timberlake, J, Tritz, KL, Unterberg, EA, von Halle, A, Wilgen, J, Williams, M, Wilson, JR, Xu, X, Zweben, SJ, Akers, R, Barry, RE, Beiersdorfer, P, Bialek, JM, Blagojevic, B, Bonoli, PT, Carter, MD, Davis, W, and Deng, B

Abstract

Research on the spherical torus (or spherical tokamak) (ST) is being pursued to explore the scientific benefits of modifying the field line structue fro that in more moderate aspect ratio devices. The ST experiments are being conducted in various US research facilities. The area of power and particle handling is expected to be challenging because of the higher power density expected in the ST relative to that in conventional aspect-ratio tokamaks.

Published
2003
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6. Physics of high performance deuterium-tritium plasmas in TFTR

Author

McGuire, KM, Barnes, CW, Batha, SH, Beer, MA, Bell, MG, Bell, RE, Belov, A, Berk, HL, Bernabei, S, Bitter, M, Breizman, BN, Bretz, NL, Budny, RV, Bush, CE, Callen, JD, Cauffman, S, Chang, CS, Chang, Z, Cheng, CZ, Cottrell, GA, Darrow, DS, Dendy, RO, Dorland, W, Duong, H, Efthimion, PC, Ernst, D, Evenson, H, Fisch, NJ, Fisher, R, Fonck, RJ, Forest, CB, Fredrickson, ED, Fu, GY, Furth, HP, Goloborod'ko, VY, Gorelenkov, NN, Grek, B, Grisham, LR, Hammett, GW, Hanson, GR, Hawryluk, RJ, Heidbrink, WW, Herrmann, HW, Herrmann, M, Hill, KW, Hogan, J, Hooper, B, Hosea, JC, Houlberg, WA, Hughes, M, Hulse, RA, Jassby, DL, Jobes, FC, Johnson, DW, Kaita, R, Kaye, SM, Kesner, J, Kim, JS, Kissick, M, Krasilnikov, AV, Kugel, HW, Kumar, A, Lam, NT, LaMarche, P, LeBlanc, B, Levinton, FM, Ludescher, C, Machuzak, J, Majeski, R, Manickam, J, Mansfield, DK, Mauel, ME, Mazzucato, E, McChesney, J, McCune, DC, McKee, G, Meade, DM, Medley, SS, Mika, R, Mikkelsen, DR, Mirnov, SV, Mueller, D, Nagayama, Y, Navratil, GA, Nazikian, R, Okabayashi, M, Owens, DK, Park, HK, Park, W, Parks, P, Paul, SF, Petrov, MP, Phillips, CK, Phillips, M, Phillips, P, Ramsey, AT, Redi, MH, Rewoldt, G, Reznik, S, Rogers, JH, Roquemore, AL, Ruskov, E, Sabbagh, SA, Sasao, M, Schilling, G, Schivell, J, Schmidt, GL, Scott, SD, Semenov, IB, Senko, T, Sesnic, S, Skinner, CH, Stevenson, T, Stodiek, W, Strachan, JD, Strait, EJ, Stratton, BC, Synakowski, EJ, Takahashi, H, Tang, WM, Taylor, G, Terry, JL, Thompson, ME, Von Goeler, S, Von Halle, A, Walters, RT, Wang, S, White, RB, Wieland, RM, Williams, M, Wilson, JR, Wong, KL, Wurden, GA, Yamada, M, Yavorski, V, Young, KM, Zakharov, LE, Zarnstorff, MC, Zweben, SJ, and AGCY, INTAE

Published
1997

7. TFTR DT experiments

Author

Strachan, JD, Batha, S, Beer, M, Bell, MG, 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, Bendy, RO, Borland, W, Buong, H, Efthimion, PC, Ernst, B, Evenson, H, Fisch, NJ, Fisher, R, Fonck, RJ, Fredrickson, EB, 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, BL, Jobes, FC, Johnson, BW, 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, BK, Mauel, M, Mazzucato, E, McChesney, J, McCune, BC, McKee, G, McGuire, KM, Meade, BM, Medley, SS, Mikkelsen, BR, Mirnov, SV, Mueller, B, Nagayama, Y, Navratil, GA, Nazikian, R, Okabayashi, M, Osakabe, M, Owens, BK, 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, and Sasao, M

Abstract

The Tokamak Fusion Test Reactor (TFTR) is a large tokamak which has performed experiments with 50:50 deuterium-tritium fuelled plasmas. Since 1993, TFTR has produced about 1090 D-T plasmas using about 100 grams of tritium and producing about 1.6 GJ of D-T fusion energy. These plasmas have significant populations of 3.5 MeV alphas (the charged D-T fusion product). TFTR research has focused on alpha particle confinement, alpha driven modes, and alpha heating studies. Maximum D-T fusion power production has aided these studies, requiring simultaneously operation at high input heating power and large energy confinement time (to produce the highest temperature and density), while maintaining low impurity content. The principal limitation to the TFTR fusion power production was the disruptive stability limit. Secondary limitations were the confinement time, and limiter power handling capability. © 1997 IOP Publishing Ltd.

Published
1997
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9. Alpha particle losses from Tokamak Fusion Test Reactor deuterium-tritium plasmas

Author

Darrow, DS, Zweben, SJ, Batha, S, Budny, RV, Bush, CE, Chang, Z, Cheng, CZ, Duong, HH, Fang, J, Fisch, NJ, Fischer, R, Fredrickson, ED, Fu, GY, Heeter, RF, Heidbrink, WW, Herrmann, HW, Herrmann, MC, Hill, K, Jaeger, EF, James, R, Majeski, R, Medley, SS, Murakami, M, Petrov, M, Phillips, CK, Redi, MH, Ruskov, E, Spong, DA, Strait, EJ, Taylor, G, White, RB, Wilson, JR, Wong, KL, and Zarnstorff, MC

Published
1996
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10. Recent D-T results on TFTR

Author

Johnson, DW, Arunasalam, V, Barnes, CW, Batha, SH, Bateman, G, Beer, M, Bell, MG, Bell, R, Bitter, M, Bretz, NL, Budny, R, Bush, CE, Cauffman, S, Chang, CS, Chang, Z, Cheng, CZ, Darrow, DS, Dendy, R, Dorland, W, Duong, HH, Durst, R, Efthimion, PC, Ernst, D, Evenson, H, Fisch, N, Fisher, R, Fonck, RJ, Fredrickson, E, Fu, GY, Fujita, T, Furth, HP, Gorelenkov, N, Grek, B, Grisham, LR, Hammett, G, Hawryluk, RJ, Heidbrink, W, Herrmann, HW, Hill, KW, Hosea, J, Hsuan, H, Hughes, M, Janos, A, Jassby, DL, Jobes, FC, Johnson, LC, Kamperschroer, J, Kesner, J, Kotschenreuther, M, Kugel, H, Lamarche, PH, Leblanc, B, Levinton, FM, MacHuzak, J, Majeski, R, Mansfield, DK, Marmar, ES, Mazzucato, E, Mauel, M, McChesney, J, McGuire, KM, McKee, G, Meade, DM, Medley, SS, Mikkelsen, DR, Mirnov, SV, Mueller, D, Nazikian, R, Osakabe, M, Owens, DK, Park, H, Park, W, Parks, P, Paul, SF, Petrov, M, Phillips, CK, Phillips, M, Qualls, AL, Ramsey, A, Redi, MH, Rewoldt, G, Roberts, D, Rogers, J, Roquemore, AL, Ruskov, E, Sabbagh, SA, Sasao, M, Schilling, G, Schivell, J, Schmidt, GL, Scott, SD, Semenov, I, Sesnic, S, Skinner, CH, Spong, D, Stratton, BC, Strachan, JD, Stodiek, W, Synakowski, E, and Takahashi, H

Subjects
Physics::Plasma Physics
Abstract

Routine tritium operation in TFTR has permitted investigations of alpha particle physics in parameter ranges resembling those of a reactor core. ICRF wave physics in a DT plasma and the influence of isotopic mass on supershot confinement have also been studied. Continued progress has been made in optimizing fusion power production in TFTR, using extended machine capability and Li wall conditioning. Performance is currently limited by MHD stability. A new reversed magnetic shear regime is being investigated with reduced core transport and a higher predicted stability limit.

Published
1995
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11. Overview of DT results from TFTR

Author

Bell, MG, McGuire, KM, Arunasalam, V, Barnes, CW, Batha, SH, Bateman, G, Beer, MA, Bell, RE, Bitter, M, Bretz, NI, Budny, RV, Bush, CE, Cauffman, SR, Chang, Z, Chang, CS, Cheng, CZ, Darrow, DS, Dendy, RO, Dorland, W, Duong, HH, Durst, RD, Efthimion, PC, Ernst, D, Evenson, H, Fisch, NJ, Fisher, RK, Fonck, RJ, Fredrickson, ED, Fu, GY, Furth, HP, Gorelenkov, NN, Grek, B, Grisham, LR, Hammett, GW, Hanson, GR, Hawryluk, RJ, Heidbrink, WW, Herrmann, HW, Hill, KW, Hosea, JC, Hsuan, H, Hughes, MH, Hulse, RA, Janos, AC, Jassby, DI, Jobes, FC, Johnson, DW, Johnson, LC, Kesner, J, Kugel, HW, Lam, NT, Leblanc, B, Levinton, FM, MacHuzak, J, Majeski, R, Mansfield, DK, Mazzucato, E, Mauel, ME, McChesney, JM, McCune, DC, McKee, G, Meade, DM, Medley, SS, Mikkelsen, DR, Mirnov, SV, Mueller, D, Navratil, GA, Nazikian, R, Owens, DK, Park, HK, Park, W, Parks, PB, Paul, SF, Petrov, MP, Phillips, CK, Phillips, MW, Pitcher, CS, Ramsey, AT, Redi, MH, Rewoldt, G, Roberts, DR, Rogers, JH, Ruskov, E, Sabbagh, SA, Sasao, M, Schilling, G, Schivell, JF, Schmidt, GI, Scott, SD, Semenov, I, Sesnic, S, Skinner, CH, Stratton, BC, Strachan, JD, Stodiek, W, Synakowski, EJ, Takahashi, H, Tang, WM, Taylor, G, and Terry, JI

Abstract

Experiments with plasmas having nearly equal concentrations of deuterium and tritium have been carried out on TFTR. To date (September 1995), the maximum fusion power has been 10.7 MW, using 39.5 MW of neutral beam heating, in a supershot discharge and 6.7 MW in a high beta P discharge following a current ramp-down. The fusion power density in the core of the plasma has reached 2.8 MW/m3, exceeding that expected in the International Thermonuclear Experimental Reactor (ITER). The energy confinement time tau E is observed to increase in DT, relative to D plasmas, by 20% and the n1(0).T1(0). tau E product by 55%. The improvement in thermal confinement is caused primarily by a decrease in ion heat conductivity in both supershot and limiter H mode discharges. Extensive lithium pellet injection increased the confinement time to 0.27 s and enabled higher current operation in both supershot and high beta P discharges. First measurements of the confined alpha particles have been performed and found to be in good agreement with TRANSP simulations assuming classical confinement. Measurements of the alpha ash profile have been compared with simulations using particle transport coefficients from helium gas puffing experiments. The loss of energetic alpha particles to a detector at the bottom of the vessel is well described by the first-orbit loss mechanism. No loss due to alpha particle driven instabilities has yet been observed. ICRF heating of a DT plasma, using the second harmonic of tritium, has been demonstrated. DT experiments on TFTR will continue both to explore the physics underlying the ITER design and to examine some of the physics issues associated with an advanced tokamak reactor.

Published
1995
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12. Plasma-surface interactions in TFTR DT experiments

Author

Owens, DK, Adler, H, Alling, P, Ancher, C, Anderson, H, Anderson, JL, Ashcroft, D, Barnes, CW, Barnes, G, Batha, S, Bell, MG, Bell, R, Bitter, M, Blanchard, W, Bretz, NL, Budny, R, Bush, CE, Camp, R, Caorlin, M, Cauffman, S, Chang, Z, Cheng, CZ, Collins, J, Coward, G, Darrow, DS, DeLooper, J, Duong, H, Dudek, L, Durst, R, Efthimion, PC, Ernst, D, Fisher, R, Fonck, RJ, Fredrickson, E, Fromm, N, Fu, GY, Furth, HP, Gentile, C, Gorelenkov, N, Grek, B, Grisham, LR, Hammett, G, Hanson, GR, Hawryluk, RJ, Heidbrink, W, Hermann, HW, Hill, KW, Hosea, J, Hsuan, H, and Janos, A

Subjects
inorganic chemicals
Abstract

TFTR has begun its campaign to study deuterium-tritium fusion under reactor-like conditions. Variable amounts of deuterium and tritium neutral beam power have been used to maximize fusion power, study alpha heating, investigate alpha particle confinement, and search for alpha driven plasma instabilities. Additional areas of study include energy and particle transport and confinement, ICRF heating schemes for DT plasmas, tritium retention, and fusion in high βp plasmas. The majority of this work is done in the TFTR supershot confinement regime. To obtain supershots, extensive limiter conditioning using helium fueled ohmic discharges and lithium pellet injection into ohmic and neutral beam heated plasmas is performed, resulting in a low recycling limiter. The relationship between recycling and core plasma confinement has been studied by using helium, deuterium and high-Z gas puffs to simulate high recycling limiter conditions. These studies show that confinement in TFTR supershots is very sensitive to the influx of neutral particles at the plasma edge. © 1995, All rights reserved.

Published
1995
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13. Preparations for deuterium-tritium experiments on the Tokamak Fusion Test Reactor

Author

Hawryluk, RJ, Adler, H, Alling, P, Ancher, C, Anderson, H, Anderson, JL, Anderson, JW, Arunasalam, V, Ascione, G, Aschroft, D, Barnes, CW, Barnes, G, Batchelor, DB, Bateman, G, Batha, S, Baylor, LA, Beer, M, Bell, MG, Biglow, TS, Bitter, M, Blanchard, W, Bonoli, P, Bretz, NL, Brunkhorst, C, Budny, R, Burgess, T, Bush, H, Bush, CE, Camp, R, Caorlin, M, Carnevale, H, Chang, Z, Chen, L, Cheng, CZ, Chrzanowski, J, Collazo, I, Collins, J, Coward, G, Cowley, S, Cropper, M, Darrow, DS, Daugert, R, DeLooper, J, Duong, H, Dudek, L, Durst, R, Efthimion, PC, Ernst, D, Faunce, J, Fonck, RJ, Fredd, E, Fredrickson, E, Fromm, N, Fu, GY, Furth, HP, Garzotto, V, Gentile, C, Gettelfinger, G, Gilbert, J, Gioia, J, Goldfinger, RC, Golian, T, Gorelenkov, N, Gouge, MJ, Grek, B, Grisham, LR, Hammett, G, Hanson, GR, Heidbrink, W, Hermann, HW, Hill, KW, Hirshman, S, Hoffman, DJ, Hosea, J, Hulse, RA, and Hsuan, H

Abstract

The final hardware modifications for tritium operation have been completed for the Tokamak Fusion Test Reactor (TFTR) [Fusion Technol. 21, 1324 (1992)]. These activities include preparation of the tritium gas handling system, installation of additional neutron shielding, conversion of the toroidal field coil cooling system from water to a Fluorinert™ system, modification of the vacuum system to handle tritium, preparation, and testing of the neutral beam system for tritium operation and a final deuterium-deuterium (D-D) run to simulate expected deuterium-tritium (D-T) operation. Testing of the tritium system with low concentration tritium has successfully begun. Simulation of trace and high power D-T experiments using D-D have been performed. The physics objectives of D-T operation are production of ≈ 10 MW of fusion power, evaluation of confinement, and heating in deuteriumtritium plasmas, evaluation of α-particle heating of electrons, and collective effects driven by alpha particles and testing of diagnostics for confined a particles. Experimental results and theoretical modeling in support of the D-T experiments are reviewed. © 1994 American Institute of Physics.

Published
1994
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14. OVERVIEW OF RECENT TFTR RESULTS

Author

ZARNSTORFF, MC, BATEMAN, G, BATHA, SH, BEER, M, BELL, MG, BELL, RE, BIGLARI, H, BITTER, M, BOIVIN, R, BRETZ, NL, BUDNY, RV, BUSH, CE, CALLEN, JD, CHANG, Z, CHEN, L, CHENG, CZ, COWLEY, SC, DARROW, DS, DURST, RD, EFTHIMION, PC, FONCK, RJ, FREDRICKSON, ED, FU, GY, FURTH, HP, GREENE, GJ, GREK, B, GRISHAM, LR, HAMMETT, GW, HAWRYLUK, RJ, HEIDBRINK, WW, HILL, KW, HIRSHMAN, SP, HOFFMAN, DJ, HOSEA, JC, HUGHES, M, HULSE, RA, JANOS, AC, JASSBY, DL, JOBES, FC, JOHNSON, DW, JOHNSON, LC, KAMPERSCHROER, J, KESNER, J, KUGEL, H, LAMARCHE, PH, LEBLANC, B, LEVINTON, F, MACHUZAK, JS, MAJESKI, R, MANOS, DM, MANSFFIELD, DK, MARMAR, ES, MAUEL, ME, MAZZUCATO, E, MCCARTHY, MP, MCCUNE, DC, MCGUIRE, KM, MEADE, DM, MEDLEY, SS, MIKKELSEN, DR, MONTICELLO, DA, MUELLER, D, MURAKAMI, M, MURPHY, J, NAGAYAMA, Y, NAVRATIL, GA, NAZIKIAN, R, OWENS, DK, PARK, HK, PARK, W, PAUL, SF, PERKINS, FW, PERRY, E, PHILLIPS, CK, PHILLIPS, M, PITCHER, S, POMPHREY, N, RASMUSSEN, DA, REDI, MH, REWOLDT, G, RIMINI, F, ROBERTS, D, ROQUEMORE, AL, SABBAGH, SA, SCHILLING, G, SCHIVELL, J, SCHMIDT, GL, SCOTT, SD, SNIPES, JA, STEVENS, JE, STODIEK, W, STRACHAN, JD, STRATTON, BC, SYNAKOWSKI, EJ, TANG, WM, TAYLOR, G, TERRY, JL, THOMPSON, M, TOWNER, HH, TSUI, H, TUSZEWSKI, M, ULRICKSON, M, VONGOELER, S, VONHALLE, A, WIELAND, RM, WILLIAMS, M, WILSON, JR, WONG, KL, WOSKOV, P, WURDEN, GA, YAMADA, M, YOUNG, KM, ZWEBEN, SJ, and AGCY, INTAE

Published
1993

15. Suppression of Alfvén Modes on the National Spherical Torus Experiment Upgrade with Outboard Beam Injection.

Author

Fredrickson ED, Belova EV, Battaglia DJ, Bell RE, Crocker NA, Darrow DS, Diallo A, Gerhardt SP, Gorelenkov NN, LeBlanc BP, Podestà M, and Nstx-U Team

Abstract

In this Letter we present data from experiments on the National Spherical Torus Experiment Upgrade, where it is shown for the first time that small amounts of high pitch-angle beam ions can strongly suppress the counterpropagating global Alfvén eigenmodes (GAE). GAE have been implicated in the redistribution of fast ions and modification of the electron power balance in previous experiments on NSTX. The ability to predict the stability of Alfvén modes, and developing methods to control them, is important for fusion reactors like the International Tokamak Experimental Reactor, which are heated by a large population of nonthermal, super-Alfvénic ions consisting of fusion generated α's and beam ions injected for current profile control. We present a qualitative interpretation of these observations using an analytic model of the Doppler-shifted ion-cyclotron resonance drive responsible for GAE instability which has an important dependence on k_{⊥}ρ_{L}. A quantitative analysis of this data with the hym stability code predicts both the frequencies and instability of the GAE prior to, and suppression of the GAE after the injection of high pitch-angle beam ions.

Published
2017
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16. Faraday-cup-type lost fast ion detector on Heliotron J.

Author

Yamamoto S, Ogawa K, Isobe M, Darrow DS, Kobayashi S, Nagasaki K, Okada H, Minami T, Kado S, Ohshima S, Weir GM, Nakamura Y, Konoshima S, Kemmochi N, Ohtani Y, and Mizuuchi T

Abstract

A Faraday-cup type lost-fast ion probe (FLIP) has been designed and installed in Heliotron J for the purpose of the studies of interaction between fast ions and MHD instabilities. The FLIP can measure the co-going fast ions whose energy is in the range of 1.7-42.5 keV (proton) and pitch angle of 90 ∘ -140 ∘ , especially for fast ions having the injection energy of neutral beam injection (NBI). The FLIP successfully measured the re-entering passing ions and trapped lost-fast ions caused by fast-ion-driven energetic particle modes in NBI heated plasmas.

Published
2016
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17. Plasma diagnostics in spherical tokamaks with silicon charged-particle detectors.

Author

Netepenko A, Boeglin WU, Darrow DS, Ellis R, and Sibilia MJ

Abstract

Detection of charged fusion products, such as protons and tritons resulting from D(d, p) t reactions, can be used to determine the position and time dependent fusion reaction rate profile in spherical tokamak plasmas with neutral beam heating. We have developed a prototype instrument consisting of 6 ion-implanted-silicon surface barrier detectors combined with collimators in such a way that each detector can accept 3 MeV protons and 1 MeV tritons and thus provides a curved view across the plasma cross section. The combination of the results from all six detectors will provide information on the spatial distribution of the fusion reaction rate. The expected time resolution of about 1 ms makes it possible to study changes in the reaction rate due to slow variations in the neutral beam density profile, as well as rapid changes resulting from MHD instabilities. Details of the new instrument, its data acquisition system, simulation results, and electrical noise testing results are discussed in this paper. First experimental data are expected to be taken during the current experimental campaign at NSTX-U.

Published
2016
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18. Investigating fusion plasma instabilities in the Mega Amp Spherical Tokamak using mega electron volt proton emissions (invited).

Author

Perez RV, Boeglin WU, Darrow DS, Cecconello M, Klimek I, Allan SY, Akers RJ, Keeling DL, McClements KG, Scannell R, Turnyanskiy M, Angulo A, Avila P, Leon O, Lopez C, Jones OM, Conway NJ, and Michael CA

Abstract

The proton detector (PD) measures 3 MeV proton yield distributions from deuterium-deuterium fusion reactions within the Mega Amp Spherical Tokamak (MAST). The PD's compact four-channel system of collimated and individually oriented silicon detectors probes different regions of the plasma, detecting protons (with gyro radii large enough to be unconfined) leaving the plasma on curved trajectories during neutral beam injection. From first PD data obtained during plasma operation in 2013, proton production rates (up to several hundred kHz and 1 ms time resolution) during sawtooth events were compared to the corresponding MAST neutron camera data. Fitted proton emission profiles in the poloidal plane demonstrate the capabilities of this new system.

Published
2014
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19. Energetic ion loss detector on the Alcator C-Mod tokamak.

Author

Pace DC, Granetz RS, Vieira R, Bader A, Bosco J, Darrow DS, Fiore C, Irby J, Parker RR, Parkin W, Reinke ML, Terry JL, Wolfe SM, Wukitch SJ, and Zweben SJ

Abstract

A scintillator-based energetic ion loss detector has been successfully commissioned on the Alcator C-Mod tokamak. This probe is located just below the outer midplane, where it captures ions of energies up to 2 MeV resulting from ion cyclotron resonance heating. After passing through a collimating aperture, ions impact different regions of the scintillator according to their gyroradius (energy) and pitch angle. The probe geometry and installation location are determined based on modeling of expected lost ions. The resulting probe is compact and resembles a standard plasma facing tile. Four separate fiber optic cables view different regions of the scintillator to provide phase space resolution. Evolving loss levels are measured during ion cyclotron resonance heating, including variation dependent upon individual antennae.

Published
2012
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20. Concept of a charged fusion product diagnostic for NSTX.

Author

Boeglin WU, Valenzuela Perez R, and Darrow DS

Abstract

The concept of a new diagnostic for NSTX to determine the time dependent charged fusion product emission profile using an array of semiconductor detectors is presented. The expected time resolution of 1-2 ms should make it possible to study the effect of magnetohydrodynamics and other plasma activities (toroidal Alfvén eigenmodes (TAE), neoclassical tearing modes (NTM), edge localized modes (ELM), etc.) on the radial transport of neutral beam ions. First simulation results of deuterium-deuterium (DD) fusion proton yields for different detector arrangements and methods for inverting the simulated data to obtain the emission profile are discussed.

Published
2010
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21. Observation of alpha particle loss from JET plasmas during ion cyclotron resonance frequency heating using a thin foil Faraday cup detector array.

Author

Darrow DS, Cecil FE, Kiptily V, Fullard K, Horton A, and Murari A

Abstract

The loss of MeV alpha particles from JET plasmas has been measured with a set of thin foil Faraday cup detectors during third harmonic heating of helium neutral beam ions. Tail temperatures of ∼ 2 MeV have been observed, with radial scrape off lengths of a few centimeters. Operational experience from this system indicates that such detectors are potentially feasible for future large tokamaks, but careful attention to screening rf and MHD induced noise is essential.

Published
2010
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22. Modeling the response of a fast ion loss detector using orbit tracing techniques in a neutral beam prompt-loss study on the DIII-D tokamak.

Author

Pace DC, Fisher RK, García-Muñoz M, Darrow DS, Heidbrink WW, Muscatello CM, Nazikian R, Van Zeeland MA, and Zhu YB

Abstract

A numerical model describing the expected measurements of neutral beam prompt-losses by a newly commissioned fast ion loss detector (FILD) in DIII-D is presented. This model incorporates the well understood neutral beam deposition profiles from all eight DIII-D beamlines to construct a prompt-loss source distribution. The full range of detectable ion orbit phase space available to the FILD is used to calculate ion trajectories that overlap with neutral beam injection footprints. Weight functions are applied to account for the level of overlap between these detectable orbits and the spatial and velocity (pitch) properties of ionized beam neutrals. An experimental comparison is performed by firing each neutral beam individually in the presence of a ramping plasma current. Fast ion losses determined from the model are in agreement with measured losses.

Published
2010
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23. Scintillator based energetic ion loss diagnostic for the National Spherical Torus Experiment.

Author

Darrow DS

Abstract

A scintillator based energetic ion loss detector has been built and installed on the National Spherical Torus Experiment (NSTX) [Synakowski et al., Nucl. Fusion 43, 1653 (2000)] to measure the loss of neutral beam ions. The detector is able to resolve the pitch angle and gyroradius of the lost energetic ions. It has a wide acceptance range in pitch angle and energy, and is able to resolve the full, one-half, and one-third energy components of the 80 keV D neutral beams up to the maximum toroidal magnetic field of NSTX. Multiple Faraday cups have been embedded behind the scintillator to allow easy absolute calibration of the diagnostic and to measure the energetic ion loss in several ranges of pitch angle with good time resolution. Several small, vacuum compatible lamps allow simple calibration of the scintillator position within the field of view of the diagnostic's video camera.

Published
2008
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26. Fusion power production from TFTR plasmas fueled with deuterium and tritium.

Author

Strachan JD, Adler H, Alling P, Ancher C, Anderson H, Anderson JL, Ashcroft D, Barnes CW, Barnes G, Batha S, Bell MG, Bell R, Bitter M, Blanchard W, Bretz NL, Budny R, Bush CE, Camp R, Caorlin M, Cauffman S, Chang Z, Cheng CZ, Collins J, Coward G, Darrow DS, DeLooper J, Duong H, Dudek L, Durst R, Efthimion PC, Ernst D, Fisher R, Fonck RJ, Fredrickson E, Fromm N, Fu GY, Furth HP, Gentile C, Gorelenkov N, Grek B, Grisham LR, Hammett G, Hanson GR, Hawryluk RJ, Heidbrink W, Herrmann HW, Hill KW, Hosea J, Hsuan H, Janos A, Jassby DL, Jobes FC, Johnson DW, Johnson LC, Kamperschroer J, Kugel H, Lam NT, LaMarche PH, Loughlin MJ, LeBlanc B, Leonard M, Levinton FM, Machuzak J, and Mansfield DK

Published
1994
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27. Confinement and heating of a deuterium-tritium plasma.

Author

Hawryluk RJ, Adler H, Alling P, Ancher C, Anderson H, Anderson JL, Ashcroft D, Barnes CW, Barnes G, Batha S, Bell MG, Bell R, Bitter M, Blanchard W, Bretz NL, Budny R, Bush CE, Camp R, Caorlin M, Cauffman S, Chang Z, Cheng CZ, Collins J, Coward G, Darrow DS, DeLooper J, Duong H, Dudek L, Durst R, Efthimion PC, Ernst D, Fisher R, Fonck RJ, Fredrickson E, Fromm N, Fu GY, Furth HP, Gentile C, Gorelenkov N, Grek B, Grisham LR, Hammett G, Hanson GR, Heidbrink W, Herrmann HW, Hill KW, Hosea J, Hsuan H, Janos A, Jassby DL, Jobes FC, Johnson DW, Johnson LC, Kamperschroer J, Kugel H, Lam NT, LaMarche PH, Loughlin MJ, LeBlanc B, Leonard M, Levinton FM, Machuzak J, Mansfield DK, and Martin A

Published
1994
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29. Dual far infrared laser diagnostic of magnetized plasmas.

Author

Darrow DS and Park HK

Abstract

A dual far infrared laser has been constructed and its properties have been exploited to probe tokamaklike discharges in the CDX toroidal device. Thermal variation of the difference frequency between the two far infrared cavities is slow, although the cavities lack thermal stabilization, simply because their assembly on the same chassis exposes them to virtually identical temperature changes. The optical arrangement beyond the laser permits conversion within minutes between interferometry and density fluctuation observation, and within an hour between different operating wavelengths. Line average densities of 2 x 10(13) cm(-3) and coherent fluctuations in the neighborhood of 20 kHz have been measured with this diagnostic.

Published
1989
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