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

Time-dependent theoretical models have been implemented in a 1.5-D transport code to describe the operational boundaries (L-H transition, ballooning limit) in terms of edge parameters. The width of the II-mode transport barrier (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 branch of the ballooning modes is possible at high triangularity. Time dependent trajectories are calculated for several machines and the L- to H-mode transition conditions are compared with global scalings. Calibrated to one experiment (ASDEX-UP), the model yields good agreement with global scaling laws and experimental pedestal electron temperatures, and is then applied to ITER. (C) 1999 Elsevier Science B.V. All rights reserved.