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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 D α data from the DIII-D tokamak shows that Alfvén eigenmode activity degrades fast-ion confinement in many high β N, high q min, steady-state scenario discharges. (β N is the normalized plasma pressure and q min 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 q min; however, not all high q min 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) (SC-24)
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. 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, and Zhu, Yubao. Thu . "Confinement degradation by Alfvén-eigenmode induced fast-ion transport in steady-state scenario discharges". United States. doi: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},
journal = {Plasma Physics and Controlled Fusion},
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: 16 works
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