Numerical Simulation of Pure Argon Plasma Transport in a Linear Divertor Simulator

A two-dimensional numerical modeling is carried out to simulate argon plasma-neutral transport in a linear divertor simulator with an axisymmetric cylindrical geometry. A pure argon plasma flow is introduced from the source region into the transport region, and pumped out near the target plate. This numerical modeling is based on a time-dependent Braginskii's fluid formulation for plasma transport and a simple diffusion model for neutral transport. The Bohm diffusion model is adopted for calculation of radial diffusion coefficients across the parallel magnetic field in the simulator. Using the design and operation parameters of the Multi-Purpose Plasma (MP²) facility at the National Fusion Research Institute (NFRI) in Korea, argon plasma properties such as density and temperature distributions are calculated, and the formation of ionization front is found in the transport region. Plasma equilibrium profiles along the near axis turn out to be actually unaffected by the pumping positions along the cylindrical wall. Moreover, a gas target divertor concept is numerically simulated to find out puffing effects as well as pumping roles. As increasing the puffing rate at the target plate, not only the ionization front in the plasma density profile is gradually moving toward the entrance region, but also plasma density and electron temperature at the target are dramatically reduced. Two relatively peaked poles in the neutral density profile are resulted from puffing and recycling neutrals, respectively.