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Title: Confinement degradation by Alfvén-eigenmode induced fast-ion transport in steady-state scenario discharges

Abstract

Here, analysis of neutron and fast-ion Dα data from the DIII-D tokamak shows that Alfvén eigenmode activity degrades fast-ion confinement in many high βN, high qmin, steady-state scenario discharges. (βN is the normalized plasma pressure and qmin is the minimum value of the plasma safety factor.) Fast-ion diagnostics that are sensitive to the co-passing population exhibit the largest reduction relative to classical predictions. The increased fast-ion transport in discharges with strong AE activity accounts for the previously observed reduction in global confinement with increasing qmin; however, not all high qmin discharges show appreciable degradation. Two relatively simple empirical quantities provide convenient monitors of these effects: (1) an 'AE amplitude' signal based on interferometer measurements and (2) the ratio of the neutron rate to a zero-dimensional classical prediction.

Authors:
 [1];  [2];  [3];  [2];  [4];  [1];  [2];  [5];  [6];  [6];  [1];  [1]
  1. Univ. of California, Irvine, CA (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States)
  5. Chinese Academy of Sciences, Hefei (People's Republic of China)
  6. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1356336
Grant/Contract Number:  
FC02-04ER54698
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 56; Journal Issue: 9; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamaks; fast particle effects; Alfvén waves; fusion product effects

Citation Formats

Heidbrink, William W., Ferron, John R., Holcomb, Christopher T., Van Zeeland, Michael A., Chen, Xi, Collins, Cami M., Garofalo, Andrea, Gong, Xianzu, Grierson, Brian A., Podestà, Mario, Stagner, Luke, and Zhu, Yubao. Confinement degradation by Alfvén-eigenmode induced fast-ion transport in steady-state scenario discharges. United States: N. p., 2014. Web. doi:10.1088/0741-3335/56/9/095030.
Heidbrink, William W., Ferron, John R., Holcomb, Christopher T., Van Zeeland, Michael A., Chen, Xi, Collins, Cami M., Garofalo, Andrea, Gong, Xianzu, Grierson, Brian A., Podestà, Mario, Stagner, Luke, & Zhu, Yubao. Confinement degradation by Alfvén-eigenmode induced fast-ion transport in steady-state scenario discharges. United States. https://doi.org/10.1088/0741-3335/56/9/095030
Heidbrink, William W., Ferron, John R., Holcomb, Christopher T., Van Zeeland, Michael A., Chen, Xi, Collins, Cami M., Garofalo, Andrea, Gong, Xianzu, Grierson, Brian A., Podestà, Mario, Stagner, Luke, and Zhu, Yubao. 2014. "Confinement degradation by Alfvén-eigenmode induced fast-ion transport in steady-state scenario discharges". United States. https://doi.org/10.1088/0741-3335/56/9/095030. https://www.osti.gov/servlets/purl/1356336.
@article{osti_1356336,
title = {Confinement degradation by Alfvén-eigenmode induced fast-ion transport in steady-state scenario discharges},
author = {Heidbrink, William W. and Ferron, John R. and Holcomb, Christopher T. and Van Zeeland, Michael A. and Chen, Xi and Collins, Cami M. and Garofalo, Andrea and Gong, Xianzu and Grierson, Brian A. and Podestà, Mario and Stagner, Luke and Zhu, Yubao},
abstractNote = {Here, analysis of neutron and fast-ion Dα data from the DIII-D tokamak shows that Alfvén eigenmode activity degrades fast-ion confinement in many high βN, high qmin, steady-state scenario discharges. (βN is the normalized plasma pressure and qmin is the minimum value of the plasma safety factor.) Fast-ion diagnostics that are sensitive to the co-passing population exhibit the largest reduction relative to classical predictions. The increased fast-ion transport in discharges with strong AE activity accounts for the previously observed reduction in global confinement with increasing qmin; however, not all high qmin discharges show appreciable degradation. Two relatively simple empirical quantities provide convenient monitors of these effects: (1) an 'AE amplitude' signal based on interferometer measurements and (2) the ratio of the neutron rate to a zero-dimensional classical prediction.},
doi = {10.1088/0741-3335/56/9/095030},
url = {https://www.osti.gov/biblio/1356336}, journal = {Plasma Physics and Controlled Fusion},
issn = {0741-3335},
number = 9,
volume = 56,
place = {United States},
year = {Thu Aug 21 00:00:00 EDT 2014},
month = {Thu Aug 21 00:00:00 EDT 2014}
}

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Cited by: 35 works
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Works referencing / citing this record:

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


Velocity-space sensitivity of time-of-flight neutron spectrometer at EAST in deuterium plasma
journal, October 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


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


The phase-space dependence of fast-ion interaction with tearing modes
journal, July 2018


Plasma equilibrium with fast ion orbit width, pressure anisotropy, and toroidal flow effects
journal, July 2018


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


Simulation of neutron emission in neutral beam injection heated plasmas with the real-time code RABBIT
journal, June 2019


Enhanced radial energy transport induced by radially curved Alfvén eigenmode wavefronts
journal, July 2019


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