Simulation of plasma in scrape-off-layer region in Thailand Tokamak 1 using extended two-point model

Abstract

Abstract As Thailand has been preparing to operate a small tokamak in which the device will be upgraded from HT-6M tokamak, the quantitative information about the plasma in the edge and at the surface of a limiter would be insightful for planning future experimental operations. In this work, we employ an extended two-point model to investigate the particle and heat exhausted from the core to the limiter for the tokamak with nominal parameters of HT-6M. The model assumes that the transports of heat and particle from the core enter the scrape-off layer at the outer midplane (upstream point). They then travel to the limiter along the magnetic field line. In this scrape-off layer region, both the conductive and convective transport are considered. The particle sources are only present near the limiter and the conservation of momentum is assumed. Thus, in the steady state, the transport equations can be reduced to a set of nonlinear equations that relates the density and temperature at the upstream to those at the limiter. For Thailand Tokamak, as the density at the upstream point is increased from 0.1 × 1019 to 3.5 × 1019 m−3 and power through separatrix is 0.2 MW, it is found that the electron temperature at the limiter surface is reduce from 250 to 10 eV. When the upstream density is greater than 2.7 × 1019 m−3, the particle flux reaching to the limiter significantly decreases in which this suggests for the plasma detachment.