DC glow discharge modes and self-oscillations in argon

The ignition and operation modes (Townsend, subnormal and transition to abnormal or normal modes) of a glow discharge in argon have been experimentally investigated. Oscillograms of voltage between electrodes and discharge current were obtained, as well as current-voltage characteristics of glow discharge in a wide range of argon pressure and for different values of ballast resistor and external capacitance. The dependences of the amplitude values of voltage, current and frequency of oscillations on the voltage at the output of the generator were also measured. It is proposed to distinguish 2 stages of oscillations. The first stage begins when the voltage at the electrodes reaches the upper stationary value, which causes a rapid increase in current. The voltage on the electrodes decreases until it reaches the lower stationary value, the discharge current at this point reaches a maximum. The subnormal mode has a negative differential resistance, which contributes to the occurrence of self-oscillations. At the beginning of the second stage, the voltage on the electrodes continues to decrease, reaches a minimum value and then increases due to the charging of the internal and external capacitors from the generator.