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Theoretical 5 GHz lower hybrid current drive (LHCD) efficiency using power spectrum given by 0-D Brambilla code and Lower Hybrid Simulation Code (LSC) have been studied for KSTAR. In LSC simulation, RF-driven current and current drive efficiency has been found to be deeply dependent on the profiles of the plasma density and temperature as well as on current profile in order to obtain hollow current profile favorable for advance tokamak operation mode and steady state operation. The peaked density and broad temperature profile control has been found to be efficient in current drive with maximum RF-driven current larger than 400 kA/MW with very high efficiency when the peak plasma density is ranged from 0.2 to 2.0×1020 m-3, and the peak electron temperature range of 2-20 keV together with toroidal field 2-3.5 T and Ip = 0.5-2 MA. The on-/off-axis current profile controllability is also investigated through parametric scan, and small negative magnetic shear is seen at the narrow region of the off-axis for very high temperature regime and for high BT and Ip. In order to achieve the same for lower temperature regime Ip has to be lower and also for higher LH-power compromising with CD efficiency in this case. [ABSTRACT FROM AUTHOR]

A RF code named ‘hybrid’ for heating problem of mirror confinement machine is developed. The meaning of the hybrid is that the heating problem is solved partially by analytic and partially by numerical method without loss of generality. The vacuum region including an antenna current is dealt with analytic technique and usual FDM for the plasma region. In this work we propose proper boundary conditions of electric field on the axis of cylinder. We applied this method to solving the heating problem of HANBIT the mirror confinement machine located at the KBSI site. The dispersion characteristics are studied by calculating antenna radiation resistance for variance of external magnetic field strength and plasma density and also compared with the experimental data. The heating and field profiles are also investigated for given magnetic and density configurations. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

ICRF is routinely used for plasma production in HANBIT mirror machine with a slot antenna. Second ICRF system has been installed for ion heating with slow wave in the central cell. Initial experiments showed electron temperature increases in the edge region. ICRF was also found to be very effective to stabilize the interchange mode by inducing ponderomotive force. Without any stabilizing mechanisms, a very stable plasma can be obtained with ICRF only. A simulation code has been developed to understand the HANBIT ICRF discharges and the electric field data calculated from this code is used for estimating ponderomotive forces. The results show qualitatively good agreement with experimental observations. [ABSTRACT FROM AUTHOR]