A study on ion energy distribution functions and plasma potentials in helicon wave plasmas

The characteristics of high-density helicon wave plasma generated in a quartz tube of 10 cm in diameter have been studied. The optimum conditions for efficiently exciting helicon wave plasma have been investigated. It is also observed that plasma fully ionized by helicon waves has ion pumping effect. Whether the discharge is inductive or capacitive, the plasma potential is important, since it determines the energy of the ion incident on the wall. It is investigated theoretically and experimentally that the fluctuation of the plasma potentials influences the ion energy distribution functions monitored by the retarding field energy analyzer. It is also observed that the plasma potential fluctuates with peak-to-peak voltage Vp–p in the low-density mode. The radio-frequency modulation to the plasma potential is weaker in the helicon mode than in the low mode.