ISSN:
1089-7674
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Measurements in the DIII-D tokamak [J. L. Luxon et al., Plasma Physics and Controlled Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] show that edge gradients of ion and electron temperature and pressure, ∇Ti, ∇Te, ∇Pi, and ∇Pe, are good candidates for parameters which respond to the heating power to control the fundamental physics of the spontaneous Low-mode (L-mode) to High-mode (H-mode) transition. These gradients are measured in the region where the H-mode transport barrier forms and they are found to consistently increase in time during the L-phase of discharges which make a transition to H-mode. Moreover, for a fixed magnetic configuration, there is a well-defined boundary between the L-mode and H-mode states in the ∇Te−∇Pe operational space. The values of Ti, Te, Pi, and Pe, measured at this location, show smaller relative changes during the L-phase of these discharges, indicating that the scale lengths of these quantities are decreasing as the L–H transition is approached in time. These results are consistent with several theoretical models in which gradients of pressure or temperature cause the transition. © 2001 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1365104
