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Journal Articles

Development of advanced inductive scenarios for ITER

Luce, T. C.*; Challis, C. D.*; Ide, Shunsuke; Joffrin, E.*; Kamada, Yutaka; Politzer, P. A.*; Schweinzer, J.*; Sips, A. C. C.*; Stober, J.*; Giruzzi, G.*; et al.

Nuclear Fusion, 54(1), p.013015_1 - 013015_15, 2013/12

 Times Cited Count:20 Percentile:22.07(Physics, Fluids & Plasmas)

Journal Articles

Current ramps in tokamaks; From present experiments to ITER scenarios

Imbeaux, F.*; Citrin, J.*; Hobirk, J.*; Hogeweij, G. M. D.*; K$"o$chl, F.*; Leonov, V. M.*; Miyamoto, Seiji; Nakamura, Yukiharu*; Parail, V.*; Pereverzev, G. V.*; et al.

Nuclear Fusion, 51(8), p.083026_1 - 083026_11, 2011/08

 Times Cited Count:34 Percentile:14.56(Physics, Fluids & Plasmas)

Journal Articles

Integrated modeling of steady-state scenarios and heating and current drive mixes for ITER

Murakami, Masanori*; Park, J. M.*; Giruzzi, G.*; Garcia, J.*; Bonoli, P.*; Budny, R. V.*; Doyle, E. J.*; Fukuyama, Atsushi*; Hayashi, Nobuhiko; Honda, Mitsuru; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

Journal Articles

Current ramps in tokamaks; From present experiments to ITER scenarios

Imbeaux, F.*; Basiuk, V.*; Budny, R.*; Casper, T.*; Citrin, J.*; Fereira, J.*; Fukuyama, Atsushi*; Garcia, J.*; Gribov, Y. V.*; Hayashi, Nobuhiko; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

Journal Articles

Current ramps in tokamaks; From present experiments to ITER scenarios

Imbeaux, F.*; Basiuk, V.*; Budny, R.*; Casper, T.*; Citrin, J.*; Fereira, J.*; Fukuyama, Atsushi*; Garcia, J.*; Gribov, Y. V.*; Hayashi, Nobuhiko; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2010/10

In order to prepare adequate current ramp-up and ramp-down scenarios for ITER, present experiments from several tokamaks have been analyzed by means of integrated modeling in view of determining relevant heat transport models for these operation phases. The results of these studies are presented and projections to ITER current ramp-up and ramp-down scenarios are done, focusing on the baseline inductive scenario (main heating plateau current of 15 MA). Various transport models have been tested by means of integrated modeling against experimental data from ASDEX Upgrade, C-Mod, DIII-D, JET and Tore Supra, including both Ohmic plasmas and discharges with additional heating/current drive. With using the most successful models, projections to the ITER current ramp-up and ramp-down phases are carried out. Though significant differences between models appear on the electron temperature prediction, the final q-profiles reached in the simulation are rather close.

Journal Articles

Validation of on- and off-axis neutral beam current drive against experiment in DIII-D

Park, J. M.*; Murakami, Masanori*; Petty, C. C.*; Heidbrink, W. W.*; Osborne, T. H.*; Holcomb, C. T.*; Van Zeeland, M. A.*; Prater, R.*; Luce, T. C.*; Wade, M. R.*; et al.

Physics of Plasmas, 16(9), p.092508_1 - 092508_10, 2009/09

 Times Cited Count:17 Percentile:38.91(Physics, Fluids & Plasmas)

Neutral beam current drive (NBCD) experiments in DIII-D using vertically shifted plasmas to move the current drive away from the axis have clearly demonstrated robust off-axis NBCD. Time-dependent measurements of magnetic pitch angles by the motional Stark effect diagnostic are used to obtain the evolution of the poloidal magnetic flux, which indicates a broad off-axis NBCD profile with a peak at about half the plasma radius. In most cases, the measured off-axis NBCD profile is consistent with calculations using an orbit-following Monte-Carlo code for the beam ion slowing down including finite-orbit effects, provided there is no large-scale MHD activity such as Alfv$'e$n eigenmodes modes or sawteeth. Good agreement is found between the measured pitch angles and those from simulations using transport-equilibrium codes. Two-dimensional image of Doppler-shifted fast ion D$$alpha$$ light emitted by neutralized energetic ions shows clear evidence for a hollow profile of beam ion density, consistent with classical beam ion slowing down. The magnitude of off-axis NBCD is sensitive to the alignment of the beam injection relative to the helical pitch of the magnetic field lines. If the signs of B and I yield the proper helicity, both measurement and calculation indicate that the efficiency is as good as on-axis NBCD because the increased fraction of trapped electrons reduces the electron shielding of the injected ion current, in contrast with electron current drive schemes where the trapping of electrons degrades the efficiency. The measured off-axis NBCD increases approximately linearly with the injection power, although a modest amount of fast ion diffusion is needed to explain an observed difference in the NBCD profile between the measurement and the calculation at high injection power.

Journal Articles

Off-axis neutral beam current drive for advanced scenario development in DIII-D

Murakami, Masanori*; Park, J. M.*; Petty, C. C.*; Luce, T. C.*; Heidbrink, W. W.*; Osborne, T. H.*; Prater, R.*; Wade, M. R.*; Anderson, P. M.*; Austin, M. E.*; et al.

Nuclear Fusion, 49(6), p.065031_1 - 065031_8, 2009/06

 Times Cited Count:38 Percentile:15.02(Physics, Fluids & Plasmas)

Modification of the two existing DIII-D neutral beam lines is planned to allow vertical steering to provide off-axis neutral beam current drive (NBCD) peaked as far off-axis as half the plasma minor radius. New calculations for a downward-steered beam indicate strong current drive with good localization off-axis so long as the toroidal magnetic field, BT, and the plasma current, Ip, point in the same direction. This is due to good alignment of neutral beam injection (NBI) with the local pitch of the magnetic field lines. This model has been tested experimentally on DIII-D by an injecting equatorially-mounted NBs into reduced size plasmas that are vertically displaced with respect to the vessel midplane. The existence of off-axis NBCD is evident in the changes seen in sawtooth behavior in the internal inductance. By shifting the plasma upward or downward, or by changing the sign of the toroidal field, measured off-axis NBCD profiles measured with motional Stark effect data and internal loop voltage show a difference in amplitude (40%-45%) consistent with predicted differences predicted by the changed NBI alignment with respect to the helicity of the magnetic field lines. The effects of NB injection direction relative to field line helicity can be large even in ITER: off-axis NBCD can be increased by more than 20% if the BT direction is reversed. Modification of the DIII-D NB system will strongly support scenario development for ITER and future tokamaks as well as providing flexible scientific tools for understanding transport, energetic particles and heating and current drive.

Journal Articles

The 2008 public release of the international multi-tokamak confinement profile database

Roach, C. M.*; Walters, M.*; Budny, R. V.*; Imbeaux, F.*; Fredian, T. W.*; Greenwald, M.*; Stillerman, J. A.*; Alexander, D. A.*; Carlsson, J.*; Cary, J. R.*; et al.

Nuclear Fusion, 48(12), p.125001_1 - 125001_19, 2008/12

 Times Cited Count:31 Percentile:69.84(Physics, Fluids & Plasmas)

This paper documents the public release PR08 of the International Tokamak Physics Activity profile database, which should be of particular interest to the magnetic confinement fusion community. Data from a wide variety of interesting discharges from many of the world's leading tokamak experiments are now made available in PR08, which also includes predictive simulations of an initial set of operating scenarios for ITER. In this paper we describe the discharges that have been included and the tools that are available to the reader who is interested in accessing and working with the data.

Journal Articles

Experimental tests of paleoclassical transport

Callen, J. D.*; Anderson, J. K.*; Arlen, T. C.*; Bateman, G.*; Budny, R. V.*; Fujita, Takaaki; Greenfield, C. M.*; Greenwald, M.*; Groebner, R. J.*; Hill, D. N.*; et al.

Nuclear Fusion, 47(11), p.1449 - 1457, 2007/11

 Times Cited Count:6 Percentile:74.65(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Progress in the ITER physics basis, 6; Steady state operation

Gormezano, C.*; Sips, A. C. C.*; Luce, T. C.*; Ide, Shunsuke; Becoulet, A.*; Litaudon, X.*; Isayama, Akihiko; Hobirk, J.*; Wade, M. R.*; Oikawa, Toshihiro; et al.

Nuclear Fusion, 47(6), p.S285 - S336, 2007/06

 Times Cited Count:255 Percentile:22.81(Physics, Fluids & Plasmas)

This paper reviews recent world-wide progress in physics research towards International Thermonuclear Reactor (ITER). This chaper descrives on steady state operation with emphasis on: integrated scenarios, review of presently developed experimental scenarios, actuators for steady state operation, specific control issues to steady state operation, simulation of ITER steady-state and hybrid scenarios.

Journal Articles

Simulation of the hybrid and steady state advanced operating modes in ITER

Kessel, C. E.*; Giruzzi, G.*; Sips, A. C. C.*; Budny, R. V.*; Artaud, J. F.*; Basiuk, V.*; Imbeaux, F.*; Joffrin, E.*; Schneider, M.*; Luce, T.*; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03

no abstracts in English

Journal Articles

Recent progress toward high performance above the greenwald density limit in impurity seeded discharges in limiter and divertor tokamaks

Ongena, J.*; Budny, R.*; Dumortier, P.*; Jackson, G. L.*; Kubo, Hirotaka; Messiaen, A. M.*; Murakami, Masanori*; Strachan, J. D.*; Sydora, R.*; Tokar, M.*; et al.

Physics of Plasmas, 8(5), p.2188 - 2198, 2001/05

 Times Cited Count:46 Percentile:18.94(Physics, Fluids & Plasmas)

no abstracts in English

Oral presentation

Results of the variable toroidal field ripple experiments in JET

Saibene, G.*; McDonald, D. C.*; Beurskens, M.*; Salmi, A.*; Lonnroth, J. S.*; Parail, V.*; de Vries, P.*; Andrew, Y.*; Budny, R.*; Boboc, A.*; et al.

no journal, , 

This paper describes the results of dedicated experiments carried out in JET, where H-mode plasmas properties were studied for varying levels of toroidal field ripple, in the range from 0.08% (natural $$delta$$$$_{rm BT}$$ for JET) up to $${sim}$$1%. The experiments were carried out in the ELMy H-mode regime with q$$_{95}$$ =3 to 3.6, to investigate the effect of $$delta$$$$_{rm BT}$$ on pedestal and core properties of the plasma. These experiments show that toroidal field ripple has a clear effect on H-mode properties, although the physics mechanisms at the root of the reduced energy confinement with $$delta$$$$_{rm BT}$$ have not been identified unambiguously. Plasma density pump out and reduction of the global energy confinement is found for $$delta$$$$_{rm BT}$$ $$sim$$ 0.5%, but the magnitude of this effect depends on plasma parameters. Ripple may also affect pedestal pressure, as well as size and frequency of ELMs. Plasma toroidal rotation was also strongly affected by ripple.

Oral presentation

Results of ITER test blanket module mock-up experiments on DIII-D

Snipes, J. A.*; Schaffer, M. J.*; Gohil, P.*; de Vries, P.*; Fenstermacher, M. E.*; Evans, T. E.*; Gao, X. M.*; Garofalo, A.*; Gates, D. A.*; Greenfield, C. M.*; et al.

no journal, , 

A series of experiments was performed on DIII-D to mock-up the field that will be induced in a pair of ferromagnetic Test Blanket Modules (TBMs) in ITER to determine the effects of such error fields on plasma operation and performance. A set of coils producing both poloidal and toroidal fields was placed inside a re-entrant horizontal port close to the plasma. The coils produce a localized ripple due to the toroidal field (TF) + TBM up to 5.7%, which is more than four times that expected from a pair of representative 1.3 ton TBMs in ITER. The experiments show that the reduction in the toroidal rotation is sensitive to the ripple. On the other hand, the confinement is reduced by up to 15-18% for local ripple $$ge$$ 3% but is hardly affected at 1.7% local ripple.

14 (Records 1-14 displayed on this page)
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