Driving frequency effect on the heating mode transition in capacitive discharge

The evolution of the electron energy distribution function (EEDF) with various driving frequencies is investigated in capacitive discharge. While increasing the driving frequency, a significant change of the EEDF is found, the bi-Maxwellian electron energy distribution changes drastically to the Druyvesteyn-like one. This observed result can be understood as an electron heating mode transition from the collisionless to collisional heating induced by driving frequency.