1997•DSpace@MIT (Massachusetts Institute of Technology)Open access
Measurements of the H-mode pedestal region on Alcator C-Mod
A. Hubbard, R. L. Boivin, R.S. Granetz, M. Greenwald, I. H. Hutchinson, J. Irby, In, J., Kesner, B., B. LaBombard, Y. Lin, J. E. Rice, T. S. Pedersen, J. Snipes, P. C. Stek, Y. Takase, S. Wolfe, S. Wukitch
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Abstract
Measurements of the steep transport barrier at the edge of the Alcator C-Mod tokamak (I.H. Hutchinson et.al., Phys.Plasmas 1, 1511 (1994)) are presented.The parameters at the top of this barrier are in the range Te=150-750 eV and ne = 0.5 -3.3 x 1020m-3 , depending on the confinement regime.Type III Edge Localized Modes (ELMs) have an upper temperature limit.Te pedestal profiles show a barrier width AT ~8 mm.Soft x-ray emissivity profiles are narrower, with A =2-4 mm.Edge currents are calculated to alter the ideal stability boundary favourably, leading to ideally stable pedestal profiles.High frequency, broadband, edge density fluctuations are sometimes observed in H-mode and are associated with enhanced particle transport.Coherent magnetic fluctuations localized near the pedestal are also seen.
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