Transport simulation of the currentless ECRH plasma in Heliotron E

The transport of a currentless ECRH plasma in Heliotron E is studied numerically, using a 1-D transport code with an assumed RF power deposition profile. The investigated parameter range is as follows: 300 ⪅ T e ⪅ 1000 eV, T i ⪅ 120 eV, 2 < e < 10 X 10 12 cm −3 and P RF ≈ 90 kW at B = I T. Four typical models for the transport coefficients are used in the numerical calculations. It is found that a neoclassical model results in a remarkable discrepancy of the time evolution of the electron temperature T e (r) and density n e (r) profiles with regard to the measured values. The neoclassical model which includes the effects of the helical field ripple seems to simulate the saturation of T e (0), in agreement with the experimental results. This saturation is due to the dependence of . However, a consistent description of T e (r) and n e (r) cannot be given by this model. In order to reproduce the measured profiles, it is necessary to use radially increasing transport coefficients. Adding Alcator-like anomalous transport terms (independent of T e ) to the neoclassical transport model, it is found that e and P RF dependences of T e (0) can be adequately explained. The fourth model investigated has a temperature-dependent . For ions the e dependence of an anomaly factor, ,is also examined.