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Title: Development and validation of a critical gradient energetic particle driven Alfven eigenmode transport model for DIII-D tilted neutral beam experiments

Abstract

Recent experiments with the DIII-D tilted neutral beam injection (NBI) varying the beam energetic particle (EP) source profiles have provided strong evidence that unstable Alfven eigenmodes (AE) drive stiff EP transport at a critical EP density gradient. Here the critical gradient is identified by the local AE growth rate being equal to the local ITG/TEM growth rate at the same low toroidal mode number. The growth rates are taken from the gyrokinetic code GYRO. Simulation show that the slowing down beam-like EP distribution has a slightly lower critical gradient than the Maxwellian. The ALPHA EP density transport code, used to validate the model, combines the low-n stiff EP critical density gradient AE mid-core transport with the energy independent high-n ITG/TEM density transport model controling the central core EP density profile. For the on-axis NBI heated DIII-D shot 146102, while the net loss to the edge is small, about half the birth fast ions are transported from the central core r/a < 0.5 and the central density is about half the slowing down density. Lastly, these results are in good agreement with experimental fast ion pressure profiles inferred from MSE constrained EFIT equilibria.

Authors:
 [1];  [2];  [3];  [1]
  1. General Atomics, San Diego, CA (United States)
  2. Univ. of California, San Diego, CA (United States)
  3. Univ. of California, Irvine, CA (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1352905
Alternate Identifier(s):
OSTI ID: 1238865
Grant/Contract Number:  
FC02-04ER54698; FC02-08ER54977; FG02-95ER54309
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 55; Journal Issue: 12; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; energetic particles; Alfven eigenmodes; critical gradient; transport

Citation Formats

Waltz, Ronald E., Bass, Eric M., Heidbrink, William W., and VanZeeland, Michael A. Development and validation of a critical gradient energetic particle driven Alfven eigenmode transport model for DIII-D tilted neutral beam experiments. United States: N. p., 2015. Web. doi:10.1088/0029-5515/55/12/123012.
Waltz, Ronald E., Bass, Eric M., Heidbrink, William W., & VanZeeland, Michael A. Development and validation of a critical gradient energetic particle driven Alfven eigenmode transport model for DIII-D tilted neutral beam experiments. United States. https://doi.org/10.1088/0029-5515/55/12/123012
Waltz, Ronald E., Bass, Eric M., Heidbrink, William W., and VanZeeland, Michael A. 2015. "Development and validation of a critical gradient energetic particle driven Alfven eigenmode transport model for DIII-D tilted neutral beam experiments". United States. https://doi.org/10.1088/0029-5515/55/12/123012. https://www.osti.gov/servlets/purl/1352905.
@article{osti_1352905,
title = {Development and validation of a critical gradient energetic particle driven Alfven eigenmode transport model for DIII-D tilted neutral beam experiments},
author = {Waltz, Ronald E. and Bass, Eric M. and Heidbrink, William W. and VanZeeland, Michael A.},
abstractNote = {Recent experiments with the DIII-D tilted neutral beam injection (NBI) varying the beam energetic particle (EP) source profiles have provided strong evidence that unstable Alfven eigenmodes (AE) drive stiff EP transport at a critical EP density gradient. Here the critical gradient is identified by the local AE growth rate being equal to the local ITG/TEM growth rate at the same low toroidal mode number. The growth rates are taken from the gyrokinetic code GYRO. Simulation show that the slowing down beam-like EP distribution has a slightly lower critical gradient than the Maxwellian. The ALPHA EP density transport code, used to validate the model, combines the low-n stiff EP critical density gradient AE mid-core transport with the energy independent high-n ITG/TEM density transport model controling the central core EP density profile. For the on-axis NBI heated DIII-D shot 146102, while the net loss to the edge is small, about half the birth fast ions are transported from the central core r/a < 0.5 and the central density is about half the slowing down density. Lastly, these results are in good agreement with experimental fast ion pressure profiles inferred from MSE constrained EFIT equilibria.},
doi = {10.1088/0029-5515/55/12/123012},
url = {https://www.osti.gov/biblio/1352905}, journal = {Nuclear Fusion},
issn = {0029-5515},
number = 12,
volume = 55,
place = {United States},
year = {Fri Oct 30 00:00:00 EDT 2015},
month = {Fri Oct 30 00:00:00 EDT 2015}
}

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Cited by: 19 works
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Works referenced in this record:

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journal, August 2013


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Works referencing / citing this record:

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


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


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


A measure of fast ion beta at marginal stability in the reversed field pinch
journal, June 2019


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


Reduced energetic particle transport models enable comprehensive time-dependent tokamak simulations
journal, August 2019