Predictions of plasma behavior due to pellet injection for future Thailand tokamak

Thailand Institute of Nuclear Technology (TINT) was donated HT-6M tokamak by Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), China. The machine will be upgraded and installed in Nakorn-Nayok, Thailand in the near future to kick start on research and human development in the country. In the first phase of operation there will be no external heating, and hydrogen plasma in ohmic phase will be studied. Pellet injection system will be one of the main components to be developed. In this work, the investigation of injection speed, size of a pellet and the angle of injection is conducted by using simulations for providing initial results of the effect of pellets on the plasma. TASK/TR integrated modeling code is used for predicting the plasma profiles. In the core area, the anomalous transport is computed by either the theory-based current diffusive ballooning mode (CDBM) model or the Multi-Mode-95 (MMM95) model. The interaction of the pellet and the background plasma is analyzed by HPI2 code which employed the neutral gas shielding (NGS) ablation model including ∇B-drift effect. This work only considers the injection of a single pellet whose radius is between 0.2 - 0.4 mm. The injection speed is varied in the range of 100 - 1,000 m/s. Injections from both low-field and high-field sides and also investigated. The results illustrate that the pellet can penetrate deeply into the plasma core. (author)