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Title: Validating predictive models for fast ion profile relaxation in burning plasmas

Abstract

The redistribution and potential loss of energetic particles due to MHD modes can limit the performance of fusion plasmas by reducing the plasma heating rate. In this work, we present validation studies of the 1.5D critical gradient model (CGM) for Alfvén eigenmode (AE) induced EP transport in NSTX and DIII-D neutral beam heated plasmas. In previous comparisons with a single DIII-D L-mode case, the CGM model was found to be responsible for 75% of measured AE induced neutron deficit [1]. A fully kinetic HINST is used to compute mode stability for the non-perturbative version of CGM (or nCGM). We have found that AEs show strong local instability drive up to $$\gamma /\omega \sim 20\%$$ violating assumptions of perturbative approaches used in NOVA-K code. Lastly, we demonstrate that both models agree with each other and both underestimate the neutron deficit measured in DIII-D shot by approximately a factor of 2.

Authors:
 [1];  [2]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [3]; ORCiD logo [1]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Univ. of California, Irvine, CA (United States)
  3. General Atomics, San Diego, CA (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1343555
Grant/Contract Number:
AC02-09CH11466; AC03-99ER54463; FC02-04ER54698; SC-G903402
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 56; Journal Issue: 11; Conference: 14. IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems, Vienna (Austria), 1-4 Sep 2015; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; alpha particles; Alfvénic modes; magnetic fusion; reduced quasi-linear model

Citation Formats

Gorelenkov, N. N., Heidbrink, W. W., Kramer, G. J., Lestz, J. B., Podesta, M., Van Zeeland, M. A., and White, R. B.. Validating predictive models for fast ion profile relaxation in burning plasmas. United States: N. p., 2016. Web. doi:10.1088/0029-5515/56/11/112015.
Gorelenkov, N. N., Heidbrink, W. W., Kramer, G. J., Lestz, J. B., Podesta, M., Van Zeeland, M. A., & White, R. B.. Validating predictive models for fast ion profile relaxation in burning plasmas. United States. doi:10.1088/0029-5515/56/11/112015.
Gorelenkov, N. N., Heidbrink, W. W., Kramer, G. J., Lestz, J. B., Podesta, M., Van Zeeland, M. A., and White, R. B.. 2016. "Validating predictive models for fast ion profile relaxation in burning plasmas". United States. doi:10.1088/0029-5515/56/11/112015. https://www.osti.gov/servlets/purl/1343555.
@article{osti_1343555,
title = {Validating predictive models for fast ion profile relaxation in burning plasmas},
author = {Gorelenkov, N. N. and Heidbrink, W. W. and Kramer, G. J. and Lestz, J. B. and Podesta, M. and Van Zeeland, M. A. and White, R. B.},
abstractNote = {The redistribution and potential loss of energetic particles due to MHD modes can limit the performance of fusion plasmas by reducing the plasma heating rate. In this work, we present validation studies of the 1.5D critical gradient model (CGM) for Alfvén eigenmode (AE) induced EP transport in NSTX and DIII-D neutral beam heated plasmas. In previous comparisons with a single DIII-D L-mode case, the CGM model was found to be responsible for 75% of measured AE induced neutron deficit [1]. A fully kinetic HINST is used to compute mode stability for the non-perturbative version of CGM (or nCGM). We have found that AEs show strong local instability drive up to $\gamma /\omega \sim 20\%$ violating assumptions of perturbative approaches used in NOVA-K code. Lastly, we demonstrate that both models agree with each other and both underestimate the neutron deficit measured in DIII-D shot by approximately a factor of 2.},
doi = {10.1088/0029-5515/56/11/112015},
journal = {Nuclear Fusion},
number = 11,
volume = 56,
place = {United States},
year = 2016,
month = 7
}

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  • The redistribution and potential loss of energetic particles due to MHD modes can limit the performance of fusion plasmas by reducing the plasma heating rate. In this work, we present validation studies of the 1.5D critical gradient model (CGM) for Alfven eigenmode (AE) induced EP transport in NSTX and DIII-D neutral beam heated plasmas. In previous comparisons with a single DIII-D L-mode case, the CGM model was found to be responsible for 75% of measured AE induced neutron deficit [1]. A fully kinetic HINST is used to compute mode stability for the non-perturbative version of CGM (or nCGM). We havemore » found that AEs show strong local instability drive up to gamma/omega similar to 20% violating assumptions of perturbative approaches used in NOVA-K code. We demonstrate that both models agree with each other and both underestimate the neutron deficit measured in DIII-D shot by approximately a factor of 2. On the other hand in NSTX the application of CGM shows good agreement for the measured flux deficit predictions. We attempt to understand these results with the help of the so-called kick model which is based on the guiding center code ORBIT. The kick model comparison gives important insight into the underlying velocity space dependence of the AE induced EP transport as well as it allows the estimate of the neutron deficit in the presence of the low frequency Alfvenic modes. Within the limitations of used models we infer that there are missing modes in the analysis which could improve the agreement with the experiments.« less
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