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Title: Mode conversion electron heating in Alcator C-Mod: Theory and experiment

Abstract

Localized electron heating [full width at half maximum of {delta}(r/a){approx_equal}0.2] by mode converted ion Bernstein waves (IBW) has been observed in the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. These experiments were performed in D({sup 3}He) plasmas at high magnetic field (B{sub 0}=7.9 T), high-plasma density (n{sub e0}{>=}1.5x10{sup 20} m{sup -3}), and for 0.05{<=}n{sub He-3}/n{sub e}{<=}0.30. Electron heating profiles of the mode converted IBW were measured using a break in slope analysis of the electron temperature versus time in the presence of rf (radio frequency) modulation. The peak position of electron heating was found to be well-correlated with {sup 3}He concentration, in agreement with the predictions of cold plasma theory. Recently, a toroidal full-wave ion cyclotron range of frequencies (ICRF) code TORIC [M. Brambilla, Nucl. Fusion 38, 1805 (1998)] was modified to include the effects of IBW electron Landau damping at (k{sub (perpendicular} {sub sign)}{rho}{sub i}){sup 2}>>1, This model was used in combination with a 1D (one-dimensional) integral wave equation code METS [D. N. Smithe et al., Radio Frequency Power in Plasmas, AIP Conf. Proc. 403 (1997), p. 367] to analyze these experiments. Model predictions were found to be in qualitative and in somemore » instances quantitative agreement with experimental measurements. A model for mode conversion current drive (MCCD) has also been developed which combines a toroidal full wave code with an adjoint evaluation of the ICRF current drive efficiency. Predictions for off-axis MCCD in C-Mod have been made using this model and will be described. (c) 2000 American Institute of Physics.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [2]
  1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
  2. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States) (and others)
Publication Date:
OSTI Identifier:
20216057
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 7; Journal Issue: 5; Other Information: PBD: May 2000; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; MODE CONVERSION; ALCATOR DEVICE; ELECTRON BEAMS; BERNSTEIN MODE; PLASMA INSTABILITY; PLASMA HEATING; CURRENT-DRIVE HEATING; ICR HEATING; LANDAU DAMPING; HELIUM 3; EXPERIMENTAL DATA; THEORETICAL DATA

Citation Formats

Bonoli, P. T., Brambilla, M., Nelson-Melby, E., Phillips, C. K., Porkolab, M., Schilling, G., Taylor, G., Wukitch, S. J., Boivin, R. L., and Boswell, C. J. Mode conversion electron heating in Alcator C-Mod: Theory and experiment. United States: N. p., 2000. Web. doi:10.1063/1.874012.
Bonoli, P. T., Brambilla, M., Nelson-Melby, E., Phillips, C. K., Porkolab, M., Schilling, G., Taylor, G., Wukitch, S. J., Boivin, R. L., & Boswell, C. J. Mode conversion electron heating in Alcator C-Mod: Theory and experiment. United States. doi:10.1063/1.874012.
Bonoli, P. T., Brambilla, M., Nelson-Melby, E., Phillips, C. K., Porkolab, M., Schilling, G., Taylor, G., Wukitch, S. J., Boivin, R. L., and Boswell, C. J. Mon . "Mode conversion electron heating in Alcator C-Mod: Theory and experiment". United States. doi:10.1063/1.874012.
@article{osti_20216057,
title = {Mode conversion electron heating in Alcator C-Mod: Theory and experiment},
author = {Bonoli, P. T. and Brambilla, M. and Nelson-Melby, E. and Phillips, C. K. and Porkolab, M. and Schilling, G. and Taylor, G. and Wukitch, S. J. and Boivin, R. L. and Boswell, C. J.},
abstractNote = {Localized electron heating [full width at half maximum of {delta}(r/a){approx_equal}0.2] by mode converted ion Bernstein waves (IBW) has been observed in the Alcator C-Mod tokamak [I. H. Hutchinson et al., Phys. Plasmas 1, 1511 (1994)]. These experiments were performed in D({sup 3}He) plasmas at high magnetic field (B{sub 0}=7.9 T), high-plasma density (n{sub e0}{>=}1.5x10{sup 20} m{sup -3}), and for 0.05{<=}n{sub He-3}/n{sub e}{<=}0.30. Electron heating profiles of the mode converted IBW were measured using a break in slope analysis of the electron temperature versus time in the presence of rf (radio frequency) modulation. The peak position of electron heating was found to be well-correlated with {sup 3}He concentration, in agreement with the predictions of cold plasma theory. Recently, a toroidal full-wave ion cyclotron range of frequencies (ICRF) code TORIC [M. Brambilla, Nucl. Fusion 38, 1805 (1998)] was modified to include the effects of IBW electron Landau damping at (k{sub (perpendicular} {sub sign)}{rho}{sub i}){sup 2}>>1, This model was used in combination with a 1D (one-dimensional) integral wave equation code METS [D. N. Smithe et al., Radio Frequency Power in Plasmas, AIP Conf. Proc. 403 (1997), p. 367] to analyze these experiments. Model predictions were found to be in qualitative and in some instances quantitative agreement with experimental measurements. A model for mode conversion current drive (MCCD) has also been developed which combines a toroidal full wave code with an adjoint evaluation of the ICRF current drive efficiency. Predictions for off-axis MCCD in C-Mod have been made using this model and will be described. (c) 2000 American Institute of Physics.},
doi = {10.1063/1.874012},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 5,
volume = 7,
place = {United States},
year = {2000},
month = {5}
}