An approach is disclosed for generating seed electrons at a spark gap (100) in the absence of 85Kr. The present approach utilizes the photo-electric effect, using a light source (120) with a specificnominal wave length (or range of wavelengths) at a specific level of emitted flux to generate seed electrons. A spark gap (100) device is provided that includes a first electrode (104) having a firstsurface and a second electrode (102) having a second surface offset from and facing the first surface. The spark gap further includes a light source (120) configured to emit light toward at least thefirst surface such that photons emitted by the light source when the spark gap is operated are incident on the first surface and cause electron emission from the first surface.