Simulation study on a merging core fueling technique for an advanced fuel fusion spherical tokamak reactor

Highlights: • 3-D MHD simulation was performed to verify the feasibility of the merging fueling method. • The simulation reproduced the merging phenomena between the secondary and the main plasmas. • The speeds of translation and merging processes changed due to plasma viscosity. • Instability and accompanying particle loss occurred during the translation process. • Particle-tracking calculation showed that the particle fueling efficiency is up to 35%. - Abstract: With respect to a particle fueling method in a spherical tokamak reactor with an advanced fuel, we investigate the availability of a merging process following the translation of a small torus plasma through which a plasma current flows in the same direction as the main plasma. A three-dimensional resistive MHD model is used to examine the particle fueling effect by reproducing the translation process and simultaneously performing an ion trajectory calculation. The simulation shows the merging process between the translated plasma and the main plasma and exhibits potential as a particle fueling method. The results of the study indicate that up to 30% of the ions in the secondary plasma are supplied to the main plasma.