Development of a 2-D impurity fluid code for a neoclassical transport of High-Z impurities in a realistic tokamak geometry and rotation.

The accumulation of tungsten in the core region of tokamak plasmas can be a serious issue for plasma operations, as it can cause radiative cooling and dilution of the main plasma species. For evaluating impurity accumulation, it is important to know whether there is an influx or outflux of particle, which can be calculated by neoclassical kinetic analysis [1-4]. There are several characteristics that are commonly considered to affect the impurity neoclassical particle flux. The first one is a collisional regime of main ions, which can change the coefficients of the temperature screening effect [5,6]. The second factor is the poloidal asymmetry of impurity density caused by high plasma rotation [5-8] or geometric effects [9,10]. We found that the rotation can make a significant impact on particle flux in the Pfirsch-Schluter regime [7]. To comprehensively study these properties and the transport time scale evolution of impurities, we are currently developing a 2-D impurity transport fluid code in a realistic tokamak geometry and toroidal rotation. The impurity density and parallel flows are evolved by the friction and viscosity using the coefficient models in FACIT [5], in which the neoclassical kinetic radial fluxes in NEO are well fitted.