Internal transport barrier simulation and analysis in LHD

In order to study the electron heat transport channel and to clarify the electron thermal diffusivity dependence with some plasma parameters in large helical device (LHD) shots with electron internal transport barrier (elTB), some transport models have been added to the TOTAL code. These models can be divided into two categories: GyroBohm-like drift wave model and other drift wave models with shorter wavelength. A new model consisting of a n-dx of both models has also been derived for this study as a good candidate for explaining the eITB. The effect of anomalous transport reduction by the electric field shear has been introduced by means of the factor (1 + (tau f(ExB))(gamma))(-1). This factor has been previously checked as a good candidate to suppress anomalous transport in tokamak plasmas. Results show that a combination of the GyroBohm-like model and the drift wave model with shorter wavelength together with the electric field shear can explain the transition between non-eITB and elTB shots. The central temperature dependence with density is also well simulated. In the case of GyroBohm models, they also fit temperature profiles, although central temperature dependence with density is higher.