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Title: ASTRA Modeling of Electron Cyclotron Heating in the Helically Symmetric Experiment

Abstract

Thomson scattering and diamagnetic loop measurements in a hot electron plasma in the Helically Symmetric Experiment (HSX) indicate that the central electron temperature and stored energy increase linearly with power. Experimentally it is found that the central electron temperature is roughly independent of plasma density. The ASTRA code is used to model electron cyclotron heating for a magnetic configuration that is quasi-symmetric as well as for a configuration in which the symmetry is broken. The experimental results are consistent with an anomalous thermal conductivity that scales inversely with the density. However, the experimental scaling of the stored energy against density is not usually in agreement with the model. From the measured X-ray flux and the high absorbed power, as well as from the calculated low single-pass absorption efficiency, it is concluded that at low densities, a nonthermal electron population accounts for a significant fraction of the stored energy. With the ASTRA code, it is also possible to model under what conditions the central electron temperature in the quasi-symmetric configuration will be measurably greater than the temperature in the nonsymmetric configuration. These calculations depend greatly on the radial electric field of the nonsymmetric plasma but suggest that at somewhat higher densitymore » and higher power than achieved to date, differences in the central electron temperature may be observed.« less

Authors:
; ; ; ; ; ; ; ; ;  [1]
  1. The HSX Plasma Laboratory, University of Wisconsin-Madison (United States)
Publication Date:
OSTI Identifier:
20849742
Resource Type:
Journal Article
Journal Name:
Fusion Science and Technology
Additional Journal Information:
Journal Volume: 46; Journal Issue: 2; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1536-1055
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; A CODES; ABSORPTION; COMPUTERIZED SIMULATION; ECR HEATING; EFFICIENCY; ELECTRIC FIELDS; ELECTRON TEMPERATURE; ELECTRONS; HOT PLASMA; PLASMA DENSITY; PLASMA SIMULATION; STORED ENERGY; SYMMETRY; THERMAL CONDUCTIVITY; THOMSON SCATTERING; X RADIATION

Citation Formats

Talmadge, Joseph N, Likin, Konstantin M, Abdou, Ali El-Sayed Ali, Almagri, Abdulgader F, Anderson, David T, Anderson, F Simon B., Canik, John M, Deng, Chuanbao, Gerhardt, Stefan P, and Zhai, Kan. ASTRA Modeling of Electron Cyclotron Heating in the Helically Symmetric Experiment. United States: N. p., 2004. Web.
Talmadge, Joseph N, Likin, Konstantin M, Abdou, Ali El-Sayed Ali, Almagri, Abdulgader F, Anderson, David T, Anderson, F Simon B., Canik, John M, Deng, Chuanbao, Gerhardt, Stefan P, & Zhai, Kan. ASTRA Modeling of Electron Cyclotron Heating in the Helically Symmetric Experiment. United States.
Talmadge, Joseph N, Likin, Konstantin M, Abdou, Ali El-Sayed Ali, Almagri, Abdulgader F, Anderson, David T, Anderson, F Simon B., Canik, John M, Deng, Chuanbao, Gerhardt, Stefan P, and Zhai, Kan. 2004. "ASTRA Modeling of Electron Cyclotron Heating in the Helically Symmetric Experiment". United States.
@article{osti_20849742,
title = {ASTRA Modeling of Electron Cyclotron Heating in the Helically Symmetric Experiment},
author = {Talmadge, Joseph N and Likin, Konstantin M and Abdou, Ali El-Sayed Ali and Almagri, Abdulgader F and Anderson, David T and Anderson, F Simon B. and Canik, John M and Deng, Chuanbao and Gerhardt, Stefan P and Zhai, Kan},
abstractNote = {Thomson scattering and diamagnetic loop measurements in a hot electron plasma in the Helically Symmetric Experiment (HSX) indicate that the central electron temperature and stored energy increase linearly with power. Experimentally it is found that the central electron temperature is roughly independent of plasma density. The ASTRA code is used to model electron cyclotron heating for a magnetic configuration that is quasi-symmetric as well as for a configuration in which the symmetry is broken. The experimental results are consistent with an anomalous thermal conductivity that scales inversely with the density. However, the experimental scaling of the stored energy against density is not usually in agreement with the model. From the measured X-ray flux and the high absorbed power, as well as from the calculated low single-pass absorption efficiency, it is concluded that at low densities, a nonthermal electron population accounts for a significant fraction of the stored energy. With the ASTRA code, it is also possible to model under what conditions the central electron temperature in the quasi-symmetric configuration will be measurably greater than the temperature in the nonsymmetric configuration. These calculations depend greatly on the radial electric field of the nonsymmetric plasma but suggest that at somewhat higher density and higher power than achieved to date, differences in the central electron temperature may be observed.},
doi = {},
url = {https://www.osti.gov/biblio/20849742}, journal = {Fusion Science and Technology},
issn = {1536-1055},
number = 2,
volume = 46,
place = {United States},
year = {Wed Sep 15 00:00:00 EDT 2004},
month = {Wed Sep 15 00:00:00 EDT 2004}
}