1996•DSpace@MIT (Massachusetts Institute of Technology)Open access
ICRF-heated enhancement confinement modes in the Alcator C-Mod tokamak
Yuichi TAKASE, R. L. Boivin, F. Bombarda, P. T. Bonoli, C. Christensen, Cara L. Fiore, D. Garnier, John A. Goetz, S. N. Golovato, R. Granetz, M. Greenwald, Steve F. Horne, A. Hubbard, I. H. Hutchinson, J. Irby, B. Bombard, B. Lipshultz, E. Marmar, M. J. May
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Abstract
Enhanced confinement modes up to BT = 8 T have been studied with up to 3.5 MW of radiofrequency heating power at 80 MHz.H-mode is observed when the edge temperature exceeds a threshold value.H-modes with higher H factors and longer duration became possible after boronization by reducing the radiated power from the main plasma.A quasi-steady state with high confinement (H = 2.0), high pressure (ON = 1.5), low radiated power (p= 0.3), and low effective charge (Zeff = 1.5) has been obtained in Enhanced Da H-mode.This type of H-mode has enhanced levels of continuous Dc, emission and very little or no ELM activity, and reduced core particle confinement time relative to ELM-free H-mode.PEP mode is obtained by combining core fueling with pellet injection and core heating.A highly peaked pressure profile with a central value of 8atmospheres was observed.The steep pressure gradient drives off-axis bootstrap current, resulting in a shear reversed q profile.Suppression of sawteeth appears to be important in maintaining the highly peaked pressure profile.Lithium pellets were found to be more effective than deuterium pellets in raising qo.
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