Transport Simulation of JT-60U L-Mode Discharges

抄録

To study the confinement characteristics of dimensionally similardischarges (ρ^* experiments) in JT-60U L-mode plasmas, transport simulations have been carried out with three different transport models; i.e., theBohm-type, the Current-Diffusive-Ballooning-Mode and the Multi-Mode models. For all models the electron temperature is in good agreement (within 15% in the electron stored energy). If the thermal diffusivity of ions isaround two times of that of electrons, it seems that the simulation resultscould reproduce the experimental ion temperature. We have compared diffusion coefficients to study the characteristics of the ρ^* scaling ofeach transport model. In the Bohm-type model it is found that thesimulation results yield the Weak-Gyro-Bohm characteristics for electronsand ions, even though the Bohm-type thermal diffusivity is incorporated. This can be accounted for by the factor q²/L_T^* in the diffusioncoefficient. In the CDBM model, the simulationresults clearly show the Gyro-Bohm characteristics. In the Multi-Modemodel, Gyro-Bohm characteristics is predicted in the simulationresults. Since experimental results have exhibited Weak-Gyro-Bohmcharacteristics, we could conclude that the Bohm-type model which has beenempirically developed in JET L-mode plasmas might be applicable for JT-60UL-mode plasmas, as well, from the viewpoints not only of the absolute valueof plasma temperatures but also of ρ^* scaling.