LAUSR

Understanding transport in tokamak plasma is an important step toward viable nuclear fusion [1]. A study of zonal flows generated by trapped-electron mode (TEM) and trapped-ion mode (TIM) micro turbulence is presented. For this purpose the gyrokinetic code TERESA (Trapped Element REduction in Semi lagrangian Approach), which considers only trapped particles, is used [2, 3, 4, 5, 6, 7, 8]. The model enables the processing of the full f problem for trapped ions and electrons at very low numerical cost. In this paper we show that in some parameter range in gyrokinetic simulations, it is possible to apply a control method to stimulate the appearance of zonal flows while minimizing the duration of the control process and the impact on plasma parameters [9]. We also report on our observation of a hysteresis in the relation between zonal flows and electron temperature [10].