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Title: Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks

Abstract

A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak. Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significant changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. As a result, developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.

Authors:
 [1];  [2];  [1];  [3];  [2];  [1];  [1];  [1];  [1];  [2]
  1. General Atomics, San Diego, CA (United States)
  2. Univ. of California, Irvine, CA (United States)
  3. Princeton Univ., Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
Contributing Org.:
The DIII-D Team
OSTI Identifier:
1364585
Alternate Identifier(s):
OSTI ID: 1327446; OSTI ID: 1371938; OSTI ID: 1399780
Grant/Contract Number:  
AC02-09CH11466; FC02-04ER54698
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 1; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; neutral beam; tokamak; Alfvén wave; plasma control

Citation Formats

Pace, D. C., Collins, C. S., Crowley, B., Grierson, B. A., Heidbrink, W. W., Pawley, C., Rauch, J., Scoville, J. T., Van Zeeland, M. A., and Zhu, Y. B. Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks. United States: N. p., 2016. Web. doi:10.1088/0029-5515/57/1/014001.
Pace, D. C., Collins, C. S., Crowley, B., Grierson, B. A., Heidbrink, W. W., Pawley, C., Rauch, J., Scoville, J. T., Van Zeeland, M. A., & Zhu, Y. B. Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks. United States. doi:10.1088/0029-5515/57/1/014001.
Pace, D. C., Collins, C. S., Crowley, B., Grierson, B. A., Heidbrink, W. W., Pawley, C., Rauch, J., Scoville, J. T., Van Zeeland, M. A., and Zhu, Y. B. Wed . "Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks". United States. doi:10.1088/0029-5515/57/1/014001. https://www.osti.gov/servlets/purl/1364585.
@article{osti_1364585,
title = {Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks},
author = {Pace, D. C. and Collins, C. S. and Crowley, B. and Grierson, B. A. and Heidbrink, W. W. and Pawley, C. and Rauch, J. and Scoville, J. T. and Van Zeeland, M. A. and Zhu, Y. B.},
abstractNote = {A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak. Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significant changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. As a result, developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.},
doi = {10.1088/0029-5515/57/1/014001},
journal = {Nuclear Fusion},
number = 1,
volume = 57,
place = {United States},
year = {Wed Sep 28 00:00:00 EDT 2016},
month = {Wed Sep 28 00:00:00 EDT 2016}
}

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