Off-target gradient driven flows in 3D simulations of ADITYA-Upgrade tokamak scrape-off layer plasma transport

Abstract

Coupled plasma-neutral transport simulations are performed of ADITYA-Upgrade tokamak scrape-off layer (SOL) plasma where flows in the core and SOL were measured to reverse sign with density variation. The simulations per- formed using EMC3-Eirene plasma-neutral code combination incorporate the toroidally continuous high-field-side belt-limiter placed in a moderate-circular tokamak equilibrium. Development of mutually counter-propagating toroidal plasma flows in top and bottom regions of both SOL and core is recovered for relatively high upstream density cases with high input power (300 kW and 3 m 2 s −1 ). The origin of the flows is traced to the poloidal density variation introduced by high recycling on the inboard localized belt limiter. The results are compared with the similar observations, for example, in Doppler shifted passive charge exchange line emission on the ADITYA-Upgrade (ADITYA-U) tokamak , highlighting the role played by residual stress in the total Reynold stress. The external stimuli, like a localized gas puff, are discussed as potential drivers of flow, by means of residual stress, based on the existing resonant model of the tokamak plasma rotation.