Parametric Study of LH Current Drive for FED-A

In the design of FED-A, quasi-steady state operation is conceived in which the plasma current is generated by the transformer coil in the burning phase and by the lower hybrid wave in the transformer-recharging phase. A parametric study was made to obtain optimum plasma and wave parameters in the recharging phase. The plasma current saturates when rf wave power increases. In order to avoid a hollow current distribution we should choose the rf power level which gives current saturation. The saturation current level is very sensitive to the width of the wave spectrum, The optimum plasma density and n₁₁ should be determined so that the saturation current reaches to the required level and the efficiency is maximized for a given Δ n₁₁.