Modeling of electron cyclotron current drive experiments on DIII-D

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Electron Cyclotron Current Drive (ECCD) is considered a leading candidate for current profile control in Advanced Tokamak (AT) operation. Localized ECCD has been clearly demonstrated in recent proof-of-principle experiments on DIII-D. The measured ECCD efficiency near the magnetic axis agrees well with standard theoretical predictions. However, for off-axis current drive the normalized experimental efficiency does not decrease with minor radius as expected from the standard theory; the observed reduction of ECCD efficiency due to trapped electron effects in the off-axis cases is smaller than theoretical predictions. The standard approach of modeling ECCD in tokamaks has been based on the bounce-average ... continued below

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5 p.

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Lin-Liu, Y.R.; Chan, V.S.; Luce, T.C.; Prater, R.; Sauter, O. & Harvey, R.W. May 1, 1999.

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  • General Atomic Company
    Publisher Info: General Atomics, San Diego, CA (United States)
    Place of Publication: San Diego, California

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Electron Cyclotron Current Drive (ECCD) is considered a leading candidate for current profile control in Advanced Tokamak (AT) operation. Localized ECCD has been clearly demonstrated in recent proof-of-principle experiments on DIII-D. The measured ECCD efficiency near the magnetic axis agrees well with standard theoretical predictions. However, for off-axis current drive the normalized experimental efficiency does not decrease with minor radius as expected from the standard theory; the observed reduction of ECCD efficiency due to trapped electron effects in the off-axis cases is smaller than theoretical predictions. The standard approach of modeling ECCD in tokamaks has been based on the bounce-average calculations, which assume the bounce frequency is much larger than the effective collision frequency for trapped electrons at all energies. The assumption is clearly invalid at low energies. Finite collisionality will effectively reduce the trapped electron fraction, hence, increase current drive efficiency. Here, a velocity-space connection formula is proposed to estimate the collisionality effect on electron cyclotron current drive efficiency. The collisionality correction gives modest improvement in agreement between theoretical and recent DIII-D experimental results.

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5 p.

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INIS; OSTI as DE99002584

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  • 13. topical conference on applications of radio frequency power to plasmas, Annapolis, MD (United States), 12-14 Apr 1999

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  • Other: DE99002584
  • Report No.: GA--A23132
  • Report No.: CONF-990411--
  • Grant Number: AC03-99ER54463
  • Office of Scientific & Technical Information Report Number: 353436
  • Archival Resource Key: ark:/67531/metadc675280

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • May 1, 1999

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  • July 25, 2015, 2:20 a.m.

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  • Aug. 4, 2016, 7:12 p.m.

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Lin-Liu, Y.R.; Chan, V.S.; Luce, T.C.; Prater, R.; Sauter, O. & Harvey, R.W. Modeling of electron cyclotron current drive experiments on DIII-D, article, May 1, 1999; San Diego, California. (digital.library.unt.edu/ark:/67531/metadc675280/: accessed October 20, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.