ITB Formation Modeling using the ASTRA Transport Code in Reverse-Shear Plasmas

J.Y. Kim, S.S. Kim

Korea Basic Science Institute, 52 Yeoeun-dong, Yusung-Ku, Daejeon 305-333, Korea

A simulation study of the ITB (internal transport barrier) formation dynamics in reverse-shear plasmas is presented using the ASTRA (Automatic System of Transport Analysis in a tokamak) transport code. Based on the toroidal ITG (ion temperature gradient) mode driven transport model, we study the relative role of various effects, which include the marginal stability property, the negative magnetic shear, the equilibrium flow shear, and the Shafranov-shift, on the formation of ITB. The threshold input power for the ITB formation is calculated and compared in various conditions and models. The time evolution of the current, density, and temperature profiles in this simulation study is self-consistently calculated using a recent package of the ASTRA code, which includes several heating and current drive modules for NBI, ICRH, and LH systems.