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Title: Spectral effects on fast wave core heating and current drive

Abstract

Recent results obtained with high harmonic fast wave (HHFW) heating and current drive (CD) on NSTX strongly support the hypothesis that the onset of perpendicular fast wave propagation right at or very near the launcher is a primary cause for a reduction in core heating efficiency at long wavelengths that is also observed in ICRF heating experiments in numerous tokamaks. A dramatic increase in core heating efficiency was first achieved in NSTX L-mode helium majority plasmas when the onset for perpendicular wave propagation was moved away from the antenna and nearby vessel structures. Efficient core heating in deuterium majority L-mode and H-mode discharges, in which the edge density is typically higher than in comparable helium majority plasmas, was then accomplished by reducing the edge density in front of the launcher with lithium conditioning and avoiding operational points prone to instabilities. These results indicate that careful tailoring of the edge density profiles in ITER should be considered to limit radio frequency (rf) power losses to the antenna and plasma facing materials. Finally, in plasmas with reduced rf power losses in the edge regions, the first direct measurements of HHFW CD were obtained with the motional Stark effect (MSE) diagnostic. The locationmore » and radial dependence of HHFW CD measured by MSE are in reasonable agreement with predictions from both full wave and ray tracing simulations.« less

Authors:
 [1];  [1];  [2];  [3];  [3];  [3]
  1. Princeton Plasma Physics Laboratory (PPPL)
  2. Oak Ridge National Laboratory (ORNL)
  3. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1018274
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 49; Journal Issue: 7; Journal ID: ISSN 0029--5515
Country of Publication:
United States
Language:
English

Citation Formats

Phillips, Cynthia, Bell, R. E., Berry, Lee, Jaeger, Erwin Frederick, Ryan, Philip Michael, and Wilgen, John B. Spectral effects on fast wave core heating and current drive. United States: N. p., 2009. Web. doi:10.1088/0029-5515/49/7/075015.
Phillips, Cynthia, Bell, R. E., Berry, Lee, Jaeger, Erwin Frederick, Ryan, Philip Michael, & Wilgen, John B. Spectral effects on fast wave core heating and current drive. United States. doi:10.1088/0029-5515/49/7/075015.
Phillips, Cynthia, Bell, R. E., Berry, Lee, Jaeger, Erwin Frederick, Ryan, Philip Michael, and Wilgen, John B. Thu . "Spectral effects on fast wave core heating and current drive". United States. doi:10.1088/0029-5515/49/7/075015.
@article{osti_1018274,
title = {Spectral effects on fast wave core heating and current drive},
author = {Phillips, Cynthia and Bell, R. E. and Berry, Lee and Jaeger, Erwin Frederick and Ryan, Philip Michael and Wilgen, John B},
abstractNote = {Recent results obtained with high harmonic fast wave (HHFW) heating and current drive (CD) on NSTX strongly support the hypothesis that the onset of perpendicular fast wave propagation right at or very near the launcher is a primary cause for a reduction in core heating efficiency at long wavelengths that is also observed in ICRF heating experiments in numerous tokamaks. A dramatic increase in core heating efficiency was first achieved in NSTX L-mode helium majority plasmas when the onset for perpendicular wave propagation was moved away from the antenna and nearby vessel structures. Efficient core heating in deuterium majority L-mode and H-mode discharges, in which the edge density is typically higher than in comparable helium majority plasmas, was then accomplished by reducing the edge density in front of the launcher with lithium conditioning and avoiding operational points prone to instabilities. These results indicate that careful tailoring of the edge density profiles in ITER should be considered to limit radio frequency (rf) power losses to the antenna and plasma facing materials. Finally, in plasmas with reduced rf power losses in the edge regions, the first direct measurements of HHFW CD were obtained with the motional Stark effect (MSE) diagnostic. The location and radial dependence of HHFW CD measured by MSE are in reasonable agreement with predictions from both full wave and ray tracing simulations.},
doi = {10.1088/0029-5515/49/7/075015},
journal = {Nuclear Fusion},
issn = {0029--5515},
number = 7,
volume = 49,
place = {United States},
year = {2009},
month = {1}
}