Abstract—The gaseous recovery in a spark gap was investigated
by using Two-pulses method with which the tested spark gap was
broken down twice by two identical voltage pulses with a preset
time interval in between. While the first breakdown is overvolted
breakdown, the second breakdown happens usually at a voltage
much lower than the first one. By comparing the two breakdown
voltages the gaseous recovery as a function of the time interval
between the two voltage pulses was obtained. There are two
plateaus on the curve of the breakdown voltage recovery. The
first plateau appears at the voltage of about the DC static
breakdown and the second one appears when the gas is almost
fully recovered. It was found that the shorter gaps at all nitrogen
pressure tend to recover faster and the gaps with higher pressure
also tend to recover faster. If more energy is deposited in the
spark channel produced by the first breakdown, the gas
insulation recovers slower. Both the first breakdown voltage and
the second one obey Gaussian distribution. If the second
breakdown happens at the point before the end of the first
plateau on the curve of the breakdown voltage recovery, its mean
square deviation of the breakdown voltage distribution will be
smaller than that of the first breakdown. By taking photographs
of the discharge in the spark gap, it was important to find that
the spark channel produced by the second breakdown usually
does not follow that by the first breakdown. The second spark
channel is located with a distance of 0 ~ 3 mm from the first one.
The longer is the time interval between the two voltage pulses,
often the larger is the distance.