Experimental investigation on the reduction in antenna coil current during the E to H mode transition in an inductively coupled plasma

Abstract

The E to H mode transition is one of the most interesting phenomena in inductively coupled plasmas, and there is substantial evidence to show that the mode transition occurs. During the E-H mode transition, in a certain discharge condition such as low driving frequencies and high pressures, a decrease in the antenna coil current has been observed. The decrease in the coil current during the E to H mode transition at high pressures is investigated in a cylindrical inductively coupled plasma. The condition for the decrease in the coil current is derived and is analyzed through the comparison of the slopes of dissipated power and transferred power against the electron density. In addition, it is found that the electron density jump appears simultaneously with the current decrease. In order for the coil current to decrease, the slope of the dissipated power to the plasma against the electron density must be smaller than that of the transferred power, and this can be satisfied when the contribution of multistep ionization is considered in the dissipated power.