Dynamic behaviour of the L-H transition in ASDEX Upgrade
The dynamic behaviour of the L-H transition in ASDEX Upgrade is described, with emphasis on the periodic L-H-L transitions known as dithering H-mode. It is shown that there is an intrinsic timescale in this process which is characteristic of the L-H transition. A tentative explanation is given for the phenomenon using an extension of Itoh's model for the L-H transition, and it is found that the simple bifurcation model can explain qualitatively many of the experimental observations. According to the model, the dithering cycles are a limit cycle oscillation due to a difference in the response of the system to a rise in either T or n. The implications for H-mode theories are discussed.
Bibliographic Reference: Report: IPP 1/276 EN (1993) 10 pp.
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 199311517 / Last updated on: 1994-11-28
Original language: en
Available languages: en