Resonant sheath heating in weakly magnetized capacitively coupled plasmas due to electron-cyclotron motion*

An electron heating mechanism based on a resonance between the gyrating electrons and the oscillating sheath is investigated in weakly magnetized capacitively coupled plasmas at low pressure. If the electron gyrofrequency coincides with half of the driving frequency, the gyrating electrons will coherently collide with the expanding sheath, gaining substantial energy. The plasma density is thus to see a pronounced increase in the case of resonance, which is verified experimentally. Particle simulations are carried out to reveal electron kinetics by tracking the trajectory of the resonant electron. It is found that the operating pressure, electrode gap, and driving voltage are important factors characterizing the resonance effect.