Modeling of NBI Heating and Current Drive with Different Types of NBI Device Configurations in KSTAR

For flexible control of the plasma pressure and the current profiles, which is essential to achieve a high-performance plasma and its long-pulse operation, the Korea Superconducting Tokamak Advanced Research (KSTAR) is going to implement several heating and current systems, including a neutral beam injection (NB!) device. In an effort to find a more optimum configuration of the KSTAR NBI system, a simulation study of NBI heating and current drive by using the NUBEAM code for three different types of NBI configurations is given. The radial profiles of the NBI power deposition and the plasma current drive are shown to be sensitive to the NBI configurations considered, particularly in relatively low density plasmas. For a more flexible control of the off-axis current profile, a new configuration, different from the first NBI device currently installed at KSTAR, would be desirable for the second NBI system, which will be fabricated and installed in the near future.