Download or read book Evolution of Pedestal Profiles Through the L-H and H-L Transitions in Alcator C-Mod written by Amanda E. Hubbard and published by . This book was released on 2001 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Local edge electron parameters are measured in the Alcator C-Mod tokamak, during discharges in which input power is continuously ramped up and down, leading to transitions from the low-confinement (L) to high confinement (H) mode and back to L-mode. This allows measurement of the accessible portions of the non-monotonic flux-gradient relationship proposed by models of the H-mode as a critical transition. Results are consistent with a dependence of conductivity x on temperature gradient, having a very sharp decrease above a critical value. Other possible flux-gradient relations are also examined, and the data are compared with theoretical formulations. The initial transient of pedestal energy in the first few ms after the L-H transition is also analyzed and found to be consistent with a sudden decrease in x across the pedestal region.