Speaker
Description
Electron Cyclotron Heating (ECH) devices up to 6 MW have been used for plasma heating and current drive in KSTAR [1].The efficiency of the heating had been somewhat questionable since the increase of the electron temperature and the plasma stored energy saturated in some transport time scale (~10msec) are likely smaller than other heating device (e.g. NBI), and they are unexpectedly small in some of H-mode cases. Through this study, we use the GENRAY code [2] simulating the linear ray-tracing physics and compare its power damping profile with the instantaneous changes of electron temperature and plasma stored energy in sub-milliseconds measured by several ECE channels and diamagnetic loop, respectively. Additionally, to analyze the heating efficiency under various experimental conditions, we conduct the sensitivity analysis in terms of the launcher position, wave polarization, toroidal and poloidal incidence angles, and the power width. In L-mode plasmas, the comparison shows a good agreement of the power profile of GENRAY simulations with the ECE measurements, including a certain level of radial diffusion.
Figure1: Comparison of ECH power absorption profile for #31423 KSTAR experiment between GENRAY simulation (Red) and ECE measurement (black). (left) power width=4.65 degree, and (right) power width=10 degree in the GENRAY simulations
