Observations of Lower Hybrid Wave Absorption in the Scrape Off Layer of a Diverted Tokamak
Name
Whyte_Observations of.pdf
Size
662.01 KB
Format
Adobe PDF
Checksum (MD5)
b79830f55c233b5843b02e78fac0c791
Author(s)
Wallace, Gregory Marriner
Bonoli, Paul T.
Harvey, R. W.
Schmidt, Andrea Elizabeth
Smirnov, A. P.
Wilson, J. R.
Wright, John C.
Wukitch, Stephen James
Parker, R.
Whyte, Dennis G
Date Issued
November 2009
Journal
AIP Conference Proceedings
Publisher
American Institute of Physics
Citation
Wallace, G. M. et al. “Observations of Lower Hybrid Wave Absorption in the Scrape Off Layer of a Diverted Tokamak.” Gent (Belgium), 2009. 395-398. ©2009 American Institute of Physics
Version
Final published version
Abstract
The Lower Hybrid Current Drive (LHCD) system on Alcator C-Mod is designed to drive off-axis current in the core plasma, e.g. r/a<=0.8, however several interesting observations indicate that the LH waves are depositing significant power in the Scrape Off Layer (SOL) in high density L-Mode discharges. These phenomena are observed in accessible plasmas below the so-called “density limit” attributed to Parametric Decay Instabilities as omega-->2omegalh. Parallel current densities of ~500 kA/m [superscript 2] are measured on divertor Langmuir probes located just outside the separatrix during high power LH operation above n-bare~1×10[superscript 20] m[superscript −3]. These SOL currents rise at the same density at which the line integrated hard X-ray Bremsstrahlung emission drops sharply. Ray tracing/Fokker-Planck simulations over-estimate the line integrated X-ray emissivity by a factor of ~500 at n-bare = 1.4 10[superscript 20] m[superscript −3] as compared to a factor of 3–4 at n-bare = 0.6×10[superscript 20] m. Ray tracing simulations including a realistic SOL show similar trends in X-ray emission compared with the experimental observations. ©2009 American Institute of Physics
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Plasma Science and Fusion Center
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1063/1.3273775
