Towards Gyrokinetic Simulations of Multi-Scale Micro-Turbulence in Tokamaks

Abstract

Drift wave micro-turbulence at ion or electron scale has been ­extensively studied to understand the transport property over the years. It has been shown that the ion temperature gradient (ITG) driven turbulence with zonal flow dynamics­ seems to be responsible for the ion heat transport with neoclassical level in Tokamaks. However, high electron transport observed in experiments could not be successfully explained through the conventional electron temperature gradient (ETG) driven turbulence theory. While various alternative mechanisms, including the trapped electron mode (TEM) have been proposed, multi-scale micro-turbulence covering ion and electron scales may also provide a new fluctuation source and transport channel in plasmas. To simulate the nonlinear evolution of such a multi-scale ITG–ETG turbulence involving both kinetic ion and electron dynamics, a new gyrokinetic Vlasov code on high performance architectures is developed, aiming to use more than several thousands CPUs. At the first stage of the large-scale gyrokinetic simulation, the code performance is benchmarked through the calculations of the short wavelength ITG mode comparing with the theoretical results.