Observations of X-rays from Laboratory Sparks in Air at Atmospheric Pressure under Negative Switching Impulse Voltages

We present observations of X-rays from laboratory sparks created in the air at atmospheric pressure by applying an impulse voltage with long (250 mu s) rise-time. X-ray production in 35 and 46 cm gaps for three different electrode configurations was studied. The results demonstrate, for the first time, the production of X-rays in gaps subjected to switching impulses. The low rate of rise of the voltage in switching impulses does not significantly reduce the production of X-rays. Additionally, the timing of the X-ray occurrence suggests the possibility that the mechanism of X-ray production by sparks is related to the collision of streamers of opposite polarity.