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Title: Validation of the model for ELM suppression with 3D magnetic fields using low torque ITER baseline scenario discharges in DIII-D

Abstract

Here, experiments have been executed in the DIII-D tokamak to extend suppression of Edge Localized Modes (ELMs) with Resonant Magnetic Perturbations (RMPs) to ITER-relevant levels of beam torque. The results support the hypothesis for RMP ELM suppression based on transition from an ideal screened response to a tearing response at a resonant surface that prevents expansion of the pedestal to an unstable width.

Authors:
 [1];  [2];  [3];  [1];  [4];  [3];  [5];  [6];  [7];  [2];  [8];  [2];  [2];  [2];  [9];  [2];  [10];  [2];  [2];  [11] more »;  [2];  [8];  [7];  [12] « less
  1. Univ. of California, San Diego, La Jolla, CA (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. General Atomics, San Diego, CA (United States); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  5. Ludwigs Maximilians Univ., Munchen (Germany)
  6. Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)
  7. Univ. of Wisconsin-Madison, Madison, WI (United States)
  8. Univ. of California, Los Angeles, CA (United States)
  9. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  10. Columbia Univ., New York, NY (United States)
  11. The College of William and Mary, Williamsburg, VA (United States)
  12. Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); Univ. of California, Los Angeles, CA (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1398392
Grant/Contract Number:
FC02-04ER54698; AC02-76CH03073; AC05-06OR23100; AC52-07NA27344; FG02-04ER54761; FG02-07ER54917; FG02-08ER54984; FG02-08ER54999; FG02ER54809; SC0007880
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 10; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Moyer, Richard A., Paz-Soldan, Carlos, Nazikian, Raffi, Orlov, Dmitry M., Ferraro, N. M., Grierson, Brian A., Knolker, M., Lyons, B. C., McKee, George R., Osborne, Thomas H., Rhodes, T. L., Meneghini, Orso, Smith, Sterling, Evans, Todd E., Fenstermacher, Max E., Groebner, Richard J., Hanson, Jeremy M., La Haye, Robert J., Luce, Timothy C., Mordijck, Saskia, Solomon, Wayne M., Turco, Francesca, Yan, Z., and Zeng, L.. Validation of the model for ELM suppression with 3D magnetic fields using low torque ITER baseline scenario discharges in DIII-D. United States: N. p., 2017. Web. doi:10.1063/1.5000276.
Moyer, Richard A., Paz-Soldan, Carlos, Nazikian, Raffi, Orlov, Dmitry M., Ferraro, N. M., Grierson, Brian A., Knolker, M., Lyons, B. C., McKee, George R., Osborne, Thomas H., Rhodes, T. L., Meneghini, Orso, Smith, Sterling, Evans, Todd E., Fenstermacher, Max E., Groebner, Richard J., Hanson, Jeremy M., La Haye, Robert J., Luce, Timothy C., Mordijck, Saskia, Solomon, Wayne M., Turco, Francesca, Yan, Z., & Zeng, L.. Validation of the model for ELM suppression with 3D magnetic fields using low torque ITER baseline scenario discharges in DIII-D. United States. doi:10.1063/1.5000276.
Moyer, Richard A., Paz-Soldan, Carlos, Nazikian, Raffi, Orlov, Dmitry M., Ferraro, N. M., Grierson, Brian A., Knolker, M., Lyons, B. C., McKee, George R., Osborne, Thomas H., Rhodes, T. L., Meneghini, Orso, Smith, Sterling, Evans, Todd E., Fenstermacher, Max E., Groebner, Richard J., Hanson, Jeremy M., La Haye, Robert J., Luce, Timothy C., Mordijck, Saskia, Solomon, Wayne M., Turco, Francesca, Yan, Z., and Zeng, L.. 2017. "Validation of the model for ELM suppression with 3D magnetic fields using low torque ITER baseline scenario discharges in DIII-D". United States. doi:10.1063/1.5000276.
@article{osti_1398392,
title = {Validation of the model for ELM suppression with 3D magnetic fields using low torque ITER baseline scenario discharges in DIII-D},
author = {Moyer, Richard A. and Paz-Soldan, Carlos and Nazikian, Raffi and Orlov, Dmitry M. and Ferraro, N. M. and Grierson, Brian A. and Knolker, M. and Lyons, B. C. and McKee, George R. and Osborne, Thomas H. and Rhodes, T. L. and Meneghini, Orso and Smith, Sterling and Evans, Todd E. and Fenstermacher, Max E. and Groebner, Richard J. and Hanson, Jeremy M. and La Haye, Robert J. and Luce, Timothy C. and Mordijck, Saskia and Solomon, Wayne M. and Turco, Francesca and Yan, Z. and Zeng, L.},
abstractNote = {Here, experiments have been executed in the DIII-D tokamak to extend suppression of Edge Localized Modes (ELMs) with Resonant Magnetic Perturbations (RMPs) to ITER-relevant levels of beam torque. The results support the hypothesis for RMP ELM suppression based on transition from an ideal screened response to a tearing response at a resonant surface that prevents expansion of the pedestal to an unstable width.},
doi = {10.1063/1.5000276},
journal = {Physics of Plasmas},
number = 10,
volume = 24,
place = {United States},
year = 2017,
month = 9
}

Journal Article:
Free Publicly Available Full Text
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  • Recent DIII-D experiments in the ITER Baseline Scenario (IBS) have shown strong increases in fluctuations and correlated reduction of confinement associated with entering the electron-heating-dominated regime with strong electron cyclotron heating (ECH). The addition of 3.2 MW of 110 GHz EC power deposited at ρ~0.42 to IBS discharges with ~3 MW of neutral beam injection causes large increases in low-k and medium-k turbulent density fluctuations observed with Doppler backscatter (DBS), beam emission spectroscopy (BES) and phase-contrast imaging (PCI) diagnostics, correlated with decreases in the energy, particle, and momentum confinement times. Power balance calculations show the electron heat diffusivity χ emore » increases significantly in the mid-radius region 0.4« less
  • Fast Wave (FW) heating and electron cyclotron heating (ECH) are used in the DIII-D tokamak to study plasmas with low applied torque and dominant electron heating characteristic of burning plasmas. FW heating via direct electron damping has reached the 2.5 MW level in high performance ELMy H-mode plasmas. In Advanced Inductive (AI) plasmas, core FW heating was found to be comparable to that of ECH, consistent with the excellent first-pass absorption of FWs predicted by ray-tracing models at high electron beta. FW heating at the ~2 MW level to ELMy H-mode discharges in the ITER Baseline Scenario (IBS) showed unexpectedlymore » strong absorption of FW power by injected neutral beam (NB) ions, indicated by significant enhancement of the D-D neutron rate, while the intended absorption on core electrons appeared rather weak. As a result, the AI and IBS discharges are compared in an effort to identify the causes of the different response to FWs.« less
  • Experiments simulating the ITER Baseline Scenario on the DIII-D tokamak show that torque-free pure electron heating, when coupled to plasmas subject to a net co-current beam torque, affects density fluctuations at electron scales on a sub-confinement time scale, whereas fluctuations at ion scales change only after profiles have evolved to a new stationary state. Modifications to the density fluctuations measured by the Phase Contrast Imaging diagnostic (PCI) are assessed by analyzing the time evolution following the switch-off of Electron Cyclotron Heating (ECH), thus going from mixed beam/ECH to pure neutral beam heating at fixed β N . Within 20 msmore » after turning off ECH, the intensity of fluctuations is observed to increase at frequencies higher than 200 kHz; in contrast, fluctuations at lower frequency are seen to decrease in intensity on a longer time scale, after other equilibrium quantities have evolved. Non-linear gyro-kinetic modeling at ion and electron scales scales suggest that, while the low frequency response of the diagnostic is consistent with the dominant ITG modes being weakened by the slow-time increase in flow shear, the high frequency response is due to prompt changes to the electron temperature profile that enhance electron modes and generate a larger heat flux and an inward particle pinch. Furthermore, these results suggest that electron heated regimes in ITER will feature multi-scale fluctuations that might affect fusion performance via modifications to profiles.« less
  • Experiments simulating the ITER Baseline Scenario on the DIII-D tokamak show that torque-free pure electron heating, when coupled to plasmas subject to a net co-current beam torque, affects density fluctuations at electron scales on a sub confinement time scale, whereas fluctuations at ion scales change only after profiles have evolved to a new stationary state. Modifications to the density fluctuations measured by the Phase Contrast Imaging diagnostic (PCI) are assessed by analyzing the time evolution following the switch-off of Electron Cyclotron Heating (ECH), thus going from mixed beam/ECH to pure neutral beam heating at fixed βN. Within 20ms after turningmore » off ECH, the intensity of fluctuations is observed to increase at frequencies higher than 200 kHz; in contrast, fluctuations at lower frequency are seen to decrease in intensity on a longer time scale, after other equilibrium quantities have evolved. Non-linear gyro-kinetic modeling at ion and electron scales scales suggest that, while the low frequency response of the diagnostic is consistent with the dominant ITG modes being weakened by the slow-time increase in flow shear, the high frequency response is due to prompt changes to the electron temperature profile that enhance electron modes and generate a larger heat flux and an inward particle pinch. These results suggest that electron heated regimes in ITER will feature multi-scale fluctuations that might affect fusion performance via modifications to profiles.« less