Observation of hysteresis in low pressure neon inductively coupled plasmas

A hysteresis is experimentally observed during the E mode to H mode transition in neon inductively coupled plasmas. The hysteresis phenomenon has generally been observed in high pressure Ramsauer gas discharges. However, in the neon plasmas, the hysteresis of an electron density and a coil current was observed at low gas pressure (5 mTorr). Furthermore, the hysteresis phenomenon was vanished with a slight increase in gas pressure (10 mTorr). To analyze the hysteresis phenomenon, electron energy distribution functions (EEDFs) were measured with increasing and decreasing RF power. Interestingly, the measured EEDF at low gas pressure has a Maxwellian distribution in the E mode discharge and evolves to a bi-Maxwellian distribution in the H mode discharge. This evolution of the EEDF causes the hysteresis phenomenon due to a strong nonlinearity of the collisional energy loss during the E to H and the H to E transition.