Time lag characteristics of spark discharge in humid air with increased voltage

This study investigates experimentally the time lag (τ) characteristics of lightning impulse spark discharges in air with relative humidity (RH) over the range 20 to 80%. The experiment was conducted using a wire-plate electrode system with a 30 mm gap and with overvoltage of 30 to 50% of the DC sparking voltage. The statistical and formative time lags (τs and τf) are discussed relative to the effects of RH and overvoltage on electron attachment and detachment mechanisims.