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Title: Fast-ion transport in qmin >2, high-β steady state scenarios on DIII-D

Abstract

Results from experiments on DIII-D [J.L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high β steady-state operating scenarios with high- qmin confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 megawatts of neutral beam heating power is applied with the intent of maximizing βN and the noninductive current drive. However, in scenarios with qmin > 2 that target the typical range of q95 = 5-7 used in next-step steady-state reactor models, Alfvén eigenmodes cause greater fast-ion transport than classical models predict. This enhanced transport reduces the absorbed neutral beam heating power and current drive and limits the achievable βN. In contrast, similar plasmas except with qmin just above 1 have approximately classical fastion transport. Experiments that take qmin > 3 plasmas to higher βP with qmin = 11-12 for testing long pulse operation exhibit regimes of better than expected thermal confinement. Compared to the standard high- qmin scenario the high βP cases have shorter slowing-down time and lower ∇βfast , and this reduces the drive for Alfvénic modes, yielding nearly classical fast-ion transport, high values of normalized confinement, βN, and noninductive current fraction.more » These results suggest DIII-D might obtain better performance in lower- q95, high- qmin plasmas using broader neutral beam heating profiles and increased direct electron heating power to lower the drive for Alfvén eigenmodes.« less

Authors:
 [1];  [2];  [3];  [3];  [3];  [4];  [5];  [4];  [4];  [3];  [2];  [6];  [6];  [3];  [7];  [3];  [3];  [4]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Univ. of California, Irvine, CA (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  5. Chinese Academy of Sciences (CAS), Beijing (China)
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  7. Columbia Univ., New York, NY (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1329394
Alternate Identifier(s):
OSTI ID: 1228280; OSTI ID: 1258530; OSTI ID: 1356314
Report Number(s):
LLNL-JRNL-694459
Journal ID: ISSN 1070-664X
Grant/Contract Number:  
FC02-04ER54698; AC02-09CH1146; AC05-00OR22725; AC52-07NA27344; FG02-04ER54761; SCG903402
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; 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; 70 PLASMA PHYSICS AND FUSION

Citation Formats

Holcomb, Christopher T., Heidbrink, William W., Ferron, John R., Van Zeeland, Michael A., Garofalo, Andrea M., Solomon, Wayne M., Gong, Xianzu, Mueller, Dennis, Grierson, Brian A., Bass, Eric M., Collins, Cami S., Park, Jim M., Kim, Kyungjin, Luce, Timothy C., Turco, Francesca, Pace, David C., Ren, Qilong, and Podesta, Mario. Fast-ion transport in qmin >2, high-β steady state scenarios on DIII-D. United States: N. p., 2015. Web. doi:10.1063/1.4921152.
Holcomb, Christopher T., Heidbrink, William W., Ferron, John R., Van Zeeland, Michael A., Garofalo, Andrea M., Solomon, Wayne M., Gong, Xianzu, Mueller, Dennis, Grierson, Brian A., Bass, Eric M., Collins, Cami S., Park, Jim M., Kim, Kyungjin, Luce, Timothy C., Turco, Francesca, Pace, David C., Ren, Qilong, & Podesta, Mario. Fast-ion transport in qmin >2, high-β steady state scenarios on DIII-D. United States. https://doi.org/10.1063/1.4921152
Holcomb, Christopher T., Heidbrink, William W., Ferron, John R., Van Zeeland, Michael A., Garofalo, Andrea M., Solomon, Wayne M., Gong, Xianzu, Mueller, Dennis, Grierson, Brian A., Bass, Eric M., Collins, Cami S., Park, Jim M., Kim, Kyungjin, Luce, Timothy C., Turco, Francesca, Pace, David C., Ren, Qilong, and Podesta, Mario. 2015. "Fast-ion transport in qmin >2, high-β steady state scenarios on DIII-D". United States. https://doi.org/10.1063/1.4921152. https://www.osti.gov/servlets/purl/1329394.
@article{osti_1329394,
title = {Fast-ion transport in qmin >2, high-β steady state scenarios on DIII-D},
author = {Holcomb, Christopher T. and Heidbrink, William W. and Ferron, John R. and Van Zeeland, Michael A. and Garofalo, Andrea M. and Solomon, Wayne M. and Gong, Xianzu and Mueller, Dennis and Grierson, Brian A. and Bass, Eric M. and Collins, Cami S. and Park, Jim M. and Kim, Kyungjin and Luce, Timothy C. and Turco, Francesca and Pace, David C. and Ren, Qilong and Podesta, Mario},
abstractNote = {Results from experiments on DIII-D [J.L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high β steady-state operating scenarios with high- qmin confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 megawatts of neutral beam heating power is applied with the intent of maximizing βN and the noninductive current drive. However, in scenarios with qmin > 2 that target the typical range of q95 = 5-7 used in next-step steady-state reactor models, Alfvén eigenmodes cause greater fast-ion transport than classical models predict. This enhanced transport reduces the absorbed neutral beam heating power and current drive and limits the achievable βN. In contrast, similar plasmas except with qmin just above 1 have approximately classical fastion transport. Experiments that take qmin > 3 plasmas to higher βP with qmin = 11-12 for testing long pulse operation exhibit regimes of better than expected thermal confinement. Compared to the standard high- qmin scenario the high βP cases have shorter slowing-down time and lower ∇βfast , and this reduces the drive for Alfvénic modes, yielding nearly classical fast-ion transport, high values of normalized confinement, βN, and noninductive current fraction. These results suggest DIII-D might obtain better performance in lower- q95, high- qmin plasmas using broader neutral beam heating profiles and increased direct electron heating power to lower the drive for Alfvén eigenmodes.},
doi = {10.1063/1.4921152},
url = {https://www.osti.gov/biblio/1329394}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = ,
volume = 22,
place = {United States},
year = {Fri May 22 00:00:00 EDT 2015},
month = {Fri May 22 00:00:00 EDT 2015}
}

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Works referenced in this record:

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Works referencing / citing this record:

Fast-ion transport by Alfvén eigenmodes above a critical gradient threshold
journal, May 2017


Integrated modeling of high β N steady state scenario on DIII-D
journal, January 2018


Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks
journal, May 2018


Integrated Tokamak modeling: When physics informs engineering and research planning
journal, May 2018


Diagnosis of fast ions produced by negative-ion neutral-beam injection with fast-ion deuterium-alpha spectroscopy
journal, July 2019


Effects of energetic particle phase space modifications by instabilities on integrated modeling
journal, July 2016


Progress of physics understanding for long pulse high-performance plasmas on EAST towards the steady-state operation of ITER and CFETR
journal, December 2019


Phase-space dependent critical gradient behavior of fast-ion transport due to Alfvén eigenmodes
journal, June 2017


Active real-time control of Alfvén eigenmodes by neutral beam and electron cyclotron heating in the DIII-D tokamak
journal, September 2018


Subdominant modes and optimization trends of DIII-D reverse magnetic shear configurations
journal, February 2019


Feedback control of stored energy and rotation with variable beam energy and perveance on DIII-D
journal, May 2019


Alfvén eigenmodes and fast ion transport in negative triangularity DIII-D plasmas
journal, June 2019


Improved high-performance fully non-inductive discharge by optimizing the fast-ion confinement on EAST
journal, October 2019