Self-Adjusting Characterization for Steady-State, Direct Current Cathode-Dominated Glow Discharge Plasmas at High Pressures

A steady-state, direct-current high-pressure CH₄-H₂ glow discharge in a cup-shaped cathode parallel to anode configuration is investigated by using their V–I characteristics and CCD images. The discharges display an abnormal glow feature, and an expansion of a negative glow is observed on the cathode sidewall with the increasing discharge current. There exists a dependence of voltage on gas pressure for different fixed currents. The voltage decreases with gas pressure initially, and then increases conversely, which is correlated with the glow states of the cathode sidewall. This study exhibits a self-adjusting characterization for plasmas in cathode fall, which is important for maintaining steady-state, abnormal glow discharge in a relatively high pressure range.