KEY PARAMETERS FOR THE CONFINEMENT OF NEUTRAL BEAM HEATED TOKAMAKS
The parameters and processes governing the low and high (L and H) confinement in ASDEX are investigated by computer modelling. The L transport is shown to be connected with the non-Ohmic electron heating. After neutral injection, the L phase is maintained by the ion electron energy transfer rate for the significant time span of about 100 ms. It is found that the profile parameters eta-e,i = d ln T-e,i/d 1n n discriminate between the L transport and the H transport. Small $gh values around unity characterize the H regime, while larger eta values correspond to the L regime. The operational limits of the H-mode are connected with variations of eta-e and eta-i due to changes in the injection heating profile. These results suggest that drift instabilities such as dissipative trapped electron modes are involved in the anomalous L and H transport.
Bibliographic Reference: NUCLEAR FUSION, VOL. 26 (1986), NO. 4, PP. 415-423
Record Number: 1989125044100 / Last updated on: 1987-07-01
Available languages: en