Construction of the Korea superconducting tokamak advanced research (KSTAR) tokamak is in its final phase. For the long-pulse KSTAR discharges, the ion cyclotron range of frequencies (ICRF) and neutral beam injection (NBI) heating systems are expected to play important roles through a selective heating of ions and electrons, control of the plasma pressure and current profiles, a core fuelling and beam diagnostics for the KSTAR. In addition, the ICRF system is expected to be used for possible discharge cleaning and assisting in the tokamak startup. In this paper, the recent progress in the development of the ICRF and the NBI heating systems is described. The four-strap ICRF antenna has been successfully tested for a voltage up to 41 kV for a pulse length of 300 s (to 46 kV for 20 s) in a test chamber. A prototype KSTAR NBI system has been developed. At present, the system has successfully produced a 1 MW beam power for 200 s and a 3.5 MW output beam power for 4 s.
In this study it is found that the cusp magnetic field configuration of an anode bucket influences the primary electron behavior. An electron orbit code (ELEORBIT code) showed that an azimuthal line cusp (cusp lines run azimuthally with respect to the beam extraction direction) provides a longer primary electron confinement time than an axial line cusp configuration. Experimentally higher plasma densities were obtained under the same arc power when the azimuthal cusp chamber was used. The newly designed azimuthal cusp bucket has been investigated in an effort to increase the plasma density in its plasma generator per arc power.
Ion optics of three accelerator geometries was studied in terms of an analytic linear optics analysis, a numerical simulation using the IGUN program, an optical multichannel measurement of Doppler-shifted H(alpha) lines, and a water-flow calorimetry on the beam absorbing target. In general, there was a reasonable agreement observed between the four analysis methods and thus the theoretical analyses can be utilized with confidence for design iteration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.