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Title: Application of very high harmonic fast waves for off-axis current drive in the DIII-D and FNSF-AT tokamaks

Journal Article · · Nuclear Fusion
 [1];  [1];  [1];  [2];  [3];  [4]
  1. General Atomics, San Diego, CA (United States)
  2. General Atomics, San Diego, CA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  3. Oak Ridge Institute for Science Education, Oak Ridge, TN (United States)
  4. Kurchatov Institute, Moscow (Russia)
+ Show Author Affiliations

Fast waves at frequencies far above the ion cyclotron frequency and approaching the lower hybrid frequency (also called “helicons” or “whistlers”) have application to off-axis current drive in tokamaks with high electron beta. The high frequency causes the whistler-like behavior of the wave power nearly following field lines, but with a small radial component, so the waves spiral slowly toward the plasma center. The high frequency also contributes to strong damping. Modeling predicts robust off-axis current drive with good efficiency compared to alternatives in high performance discharges in DIII-D and Fusion Nuclear Science Facility (FNSF) when the electron beta is above about 1.8%. Detailed analysis of ray behavior shows that ray trajectories and damping are deterministic (that is, not strongly affected by plasma profiles or initial ray conditions), unlike the chaotic ray behavior in lower frequency fast wave experiments. Current drive was found to not be sensitive to the launched value of the parallel index of refraction n||, so wave accessibility issues can be reduced. Finally, use of a traveling wave antenna provides a very narrow n|| spectrum, which also helps avoid accessibility problems.

Research Organization:
General Atomics, San Diego, CA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
FC02-04ER54698
OSTI ID:
1351082
Journal Information:
Nuclear Fusion, Vol. 54, Issue 8; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 59 works
Citation information provided by
Web of Science

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Cited By (7)

Coupling study of fast wave near the lower hybrid frequency range in VEST journal August 2018
Whistler waves with angular momentum in space and laboratory plasmas and their counterparts in free space journal July 2016
Cold plasma finite element wave model for helicon waves journal February 2019
Survey of heating and current drive for K-DEMO journal January 2018
AORSA full wave calculations of helicon waves in DIII-D and ITER journal April 2018
Experiments on helicons in DIII-D—investigation of the physics of a reactor-relevant non-inductive current drive technology journal July 2018
Ultrafast wave-particle energy transfer in the collapse of standing whistler waves journal November 2019

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Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
current drive
fast wave
tokamak