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Title: Long-pulse stability limits of the ITER baseline scenario

Abstract

DIII-D has made significant progress in developing the techniques required to operate ITER, and in understanding their impact on performance when integrated into operational scenarios at ITER relevant parameters. We demonstrated long duration plasmas, stable to m/n =2/1 tearing modes (TMs), with an ITER similar shape and I p/aB T, in DIII-D, that evolve to stationary conditions. The operating region most likely to reach stable conditions has normalized pressure, B N≈1.9–2.1 (compared to the ITER baseline design of 1.6 – 1.8), and a Greenwald normalized density fraction, f GW 0.42 – 0.70 (the ITER design is f GW ≈ 0.8). The evolution of the current profile, using internal inductance (l i) as an indicator, is found to produce a smaller fraction of stable pulses when l i is increased above ≈ 1.1 at the beginning of β N flattop. Stable discharges with co-neutral beam injection (NBI) are generally accompanied with a benign n=2 MHD mode. However if this mode exceeds ≈ 10 G, the onset of a m/n=2/1 tearing mode occurs with a loss of confinement. In addition, stable operation with low applied external torque, at or below the extrapolated value expected for ITER has also been demonstrated. With electronmore » cyclotron (EC) injection, the operating region of stable discharges has been further extended at ITER equivalent levels of torque and to ELM free discharges at higher torque but with the addition of an n=3 magnetic perturbation from the DIII-D internal coil set. Lastly, the characterization of the ITER baseline scenario evolution for long pulse duration, extension to more ITER relevant values of torque and electron heating, and suppression of ELMs have significantly advanced the physics basis of this scenario, although significant effort remains in the simultaneous integration of all these requirements.« less

Authors:
 [1];  [1];  [2];  [3];  [1];  [1];  [1];  [4];  [1];  [1];  [1]
  1. General Atomics, San Diego, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Columbia Univ., New York, NY (United States)
  4. Univ. of California, Los Angeles, CA (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1345520
Grant/Contract Number:  
FC02-04ER54698; AC02-09CH11466; FG02-04ER54761; FG02-08ER54984
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 55; Journal Issue: 2; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamaks; spherical tokamaks; plasma heating by microwaves; ECR; ICR; ICP; helicons; MHD modes; kinetic modes

Citation Formats

Jackson, G. L., Luce, T. C., Solomon, W. M., Turco, F., Buttery, R. J., Hyatt, A. W., deGrassie, J. S., Doyle, E. J., Ferron, J. R., La Haye, R. J., and Politzer, P. A. Long-pulse stability limits of the ITER baseline scenario. United States: N. p., 2015. Web. doi:10.1088/0029-5515/55/2/023004.
Jackson, G. L., Luce, T. C., Solomon, W. M., Turco, F., Buttery, R. J., Hyatt, A. W., deGrassie, J. S., Doyle, E. J., Ferron, J. R., La Haye, R. J., & Politzer, P. A. Long-pulse stability limits of the ITER baseline scenario. United States. doi:10.1088/0029-5515/55/2/023004.
Jackson, G. L., Luce, T. C., Solomon, W. M., Turco, F., Buttery, R. J., Hyatt, A. W., deGrassie, J. S., Doyle, E. J., Ferron, J. R., La Haye, R. J., and Politzer, P. A. Wed . "Long-pulse stability limits of the ITER baseline scenario". United States. doi:10.1088/0029-5515/55/2/023004. https://www.osti.gov/servlets/purl/1345520.
@article{osti_1345520,
title = {Long-pulse stability limits of the ITER baseline scenario},
author = {Jackson, G. L. and Luce, T. C. and Solomon, W. M. and Turco, F. and Buttery, R. J. and Hyatt, A. W. and deGrassie, J. S. and Doyle, E. J. and Ferron, J. R. and La Haye, R. J. and Politzer, P. A.},
abstractNote = {DIII-D has made significant progress in developing the techniques required to operate ITER, and in understanding their impact on performance when integrated into operational scenarios at ITER relevant parameters. We demonstrated long duration plasmas, stable to m/n =2/1 tearing modes (TMs), with an ITER similar shape and Ip/aBT, in DIII-D, that evolve to stationary conditions. The operating region most likely to reach stable conditions has normalized pressure, BN≈1.9–2.1 (compared to the ITER baseline design of 1.6 – 1.8), and a Greenwald normalized density fraction, fGW 0.42 – 0.70 (the ITER design is fGW ≈ 0.8). The evolution of the current profile, using internal inductance (li) as an indicator, is found to produce a smaller fraction of stable pulses when li is increased above ≈ 1.1 at the beginning of βN flattop. Stable discharges with co-neutral beam injection (NBI) are generally accompanied with a benign n=2 MHD mode. However if this mode exceeds ≈ 10 G, the onset of a m/n=2/1 tearing mode occurs with a loss of confinement. In addition, stable operation with low applied external torque, at or below the extrapolated value expected for ITER has also been demonstrated. With electron cyclotron (EC) injection, the operating region of stable discharges has been further extended at ITER equivalent levels of torque and to ELM free discharges at higher torque but with the addition of an n=3 magnetic perturbation from the DIII-D internal coil set. Lastly, the characterization of the ITER baseline scenario evolution for long pulse duration, extension to more ITER relevant values of torque and electron heating, and suppression of ELMs have significantly advanced the physics basis of this scenario, although significant effort remains in the simultaneous integration of all these requirements.},
doi = {10.1088/0029-5515/55/2/023004},
journal = {Nuclear Fusion},
number = 2,
volume = 55,
place = {United States},
year = {2015},
month = {1}
}

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