L-H transition in tokamak plasmas: 1.5-D simulations

Time-dependent theoretical models have been implemented in a 1.5-D transpor t code to describe the operational boundaries (L-H transition, ballooning l imit) in terms of edge parameters. The width of the II-mode transport barri er (F. Wagner et al., Phys. Rev. Lett. 49 (1982) 1408) is self-consistently calculated and is related to alpha(crit) Access to the second stable branc h of the ballooning modes is possible at high triangularity. Time dependent trajectories are calculated for several machines and the L- to H-mode tran sition conditions are compared with global scalings. Calibrated to one expe riment (ASDEX-UP), the model yields good agreement with global scaling laws and experimental pedestal electron temperatures, and is then applied to IT ER. (C) 1999 Elsevier Science B.V. All rights reserved.