Abstract: This work investigates the pulse-breakdown characteristics of a pre-ionization pin array in an atmospheric-pressure ArF excimer discharge. Time-resolved imaging reveals asynchronous pin breakdown, with failure locations spatially correlated to regions of reduced intensity in the main discharge. Circuit analysis shows that the parallel inductance and initial charging voltage govern the process by affecting the pin-current rise rate and the pre-ionization branch voltage. An excessively large parallel inductance leads to premature pin breakdown before magnetic-switch saturation with a low pin-current rise rate, while an excessively small inductance diverts current away from the pins and lowers the pre-ionization voltage. Increasing the initial voltage elevates the pre-ionization branch voltage and enhances the pin-current rise rate. The study concludes that an intermediate parallel inductance, combined with a sufficiently high initial voltage, provides optimal conditions for synchronized pin breakdown.