The efficacy of electrical discharges for severing bond wires and/or for forming balls at the ends of bond wires (including bond wires already severed by alternative mechanisms) is improved by performing the electrical discharges in the presence of ultraviolet light. A "spark gap" is formed between an EFO electrode and the wire, one of which serves as the cathode of the spark gap. Preferably, the ultraviolet light is directed at the element serving as the cathode of the spark gap. Providing photoemission at the cathode element of the spark gap stabilizes arc/plasma formation and produces more reliable and predictable results. This technique may be used in conjunction with negative EFO systems or with positive EFO systems, and may benefit from either direct or field-assisted photoemission.