Survey of ICRF heating experiments and enhanced performance modes in Alcator C-Mod

Y. Takase, R.L. Boivin, F. Bombarda, P.T. Bonoli, C.L. Fiore, D. Garnier, J.A. Goetz, S.N. Golovato, R.S. Granetz, M.J. Greenwald, S.F. Horne, A.E. Hubbard, I.H. Hutchinson, J.H. Irby, H. Kimura, R. Majeski, E.S. Marmar, M. May, A. Mazurenko, P. O'SheaR. Pinsker, M. Porkolab, J. Reardon, J.E. Rice, C. Rost, J. Schachter, J.A. Snipes, P. Stek, J.L. Terry, R.L. Watterson, B. Welch, S.M. Wolfe

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Abstract

Results of ICRF heating experiments in Alcator C-Mod during the November 1994 to June 1995 campaign are summarized. Efficient heating of high-density (n̄e≲ 3 × 1020m-3) plasmas was demonstrated with high power densities (up to 5 MW m-3volume averaged, 0.6 MW m-2surface averaged). These experiments were carried out with RF powers up to 3.5 MW at 80 MHz, at magnetic fields up to 8 T and plasma currents up to 1.2 MA. For on-axis hydrogen minority heating at 5.3 T, near complete absorption is achieved. Energy confinement in L-mode plasmas was found to be consistent with the ITER89-P scaling. H-mode is routinely observed when the ion ∇B drift is directed toward the X-point. The H-mode power threshold was found to scale as low as P/S(MW m-2) = 0.02 n̄6BT(1020m-3T), which is a factor of two lower than the scaling observed on other tokamaks. PEP modes with highly peaked density and ion temperature profiles and highly enhanced fusion reactivity were obtained with Li pellet injection followed by on-axis ICRF heating at both BT= 5.3 T (H minority heating) and 8 T (3He minority heating). In H-3He plasmas at BT= 6.5 T highly localized direct electron heating by the mode converted ion Bernstein wave was observed. Nearly complete absorption by electrons in a small volume resulted in an extremely high electron heating power density of Pe0≲ 30 MW m-3with FWHM ≃ 0.2 a. © 1996 IOP Publishing Ltd.
Original languageEnglish
Pages (from-to)2215 - 2229
Number of pages15
JournalPlasma Physics and Controlled Fusion
Volume38
Issue number12
DOIs
Publication statusPublished - 1996
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

Cite this

Takase, Y., Boivin, R. L., Bombarda, F., Bonoli, P. T., Fiore, C. L., Garnier, D., ... Wolfe, S. M. (1996). Survey of ICRF heating experiments and enhanced performance modes in Alcator C-Mod. Plasma Physics and Controlled Fusion, 38(12), 2215 - 2229. https://doi.org/10.1088/0741-3335/38/12/013