Comparison of pulse-modulated and continuous operation modes of a radio-frequency inductive ion source

The paper describes an experimental study of the characteristics of a pulse-modulated radio-frequency (RF) discharge sustained at low pressures, typical of the operating modes of RF gridded ion sources. The motivation for the study is the question of whether the RF pulse-modulated mode can increase the efficiency of the ion source. The ion current values extracted from an RF inductive ion source operating in continuous and pulse-modulated modes were compared. The experimental data were also compared with the parameter calculations based on a 0D numerical model of the discharge. The measurements showed that the pulse-modulated operation mode of the RF ion source had a noticeable advantage when the power of the RF generator was 140 W or lower. However, as the generator power increased, the advantage was lost because the pulse-modulated operation mode, having a higher RF power instant value, entered the region of existence sooner than the continuous mode, where the ion production cost begins to grow with RF power.