Study of Diffuse Atmospheric Discharge Transition into Spark Phase

Summary form only given. Shape, spectrum, luminescence dynamics, and electro-technical characteristics of a nanosecond discharge on a boundary of the discharge transition from a diffuse to a spark phase were studied in a geometry rod-plane in the air of an atmospheric pressure. A series of voltage pulses of damped amplitude and different (starting from negative) polarity was supplied to an interelectrode gap (4...6 cm). The voltage amplitude was ~140 kV at the first pulse rise time of 10¹³ V/s. A discharge current reached 1.2 kA. It was established that the phase of the diffuse discharge luminescence preceded the spark channel formation. A delay of the spark formation relatively to the voltage supply to the gap was varied from pulse to pulse from 60 ns up to 2 mus and more. It was discovered that a value of a displacement current, stipulated by a motion of charged particles in the phase of the gap closure, determined the parameters and probability of the spark realization. In the presented analysis of the development dynamics of the discharge main phases an important role is appropriated to thermal processes.