Expression for the thermal H-mode energy confinement time under ELM-free conditions
The design of future tokamaks, which are supposed to reach ignition with the H-mode, requires a reliable scaling expression for the H-mode energy confinement time. In the present work, an H-mode scaling expression for the thermal plasma energy confinement time has been developed by combining data from four existing divertor tokamaks, ASDEX, DIII-D, JET and PBX-M. The plasma conditions, which were as similar as possible to ensure a coherent set of data, were ELM-free deuterium discharges heated by deuterium neutral beam injection. By combining results from the four tokamaks, the parametric dependence of the thermal energy confinement on the main plasma parameters, including the three main geometrical variables, was determined. The density dependence is found to be close to zero. This dependence is compared with the existing scaling relations and the differences are analysed. Predictions for ITER are given and discussed with particular emphasis on the uncertainties. Finally, it is shown that taking the improved H-mode confinement into account by means of a simple multiplier in front of an L-mode confinement scaling expression is valid for ITER, but is not necessarily universally valid.
Bibliographic Reference: Report: IPP 4/257 EN (1992) 25 pp.
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 199211256 / Last updated on: 1994-11-29
Original language: en
Available languages: en