In this paper, parametric studies are presented of a high pressure Ar/N2 gas laser excited by an intense proton beam from a magnetically insulated diode. Using power deposition of up to 140 MW/cm3, gas pressure up to 3040 Torr, variable N2 fraction (5%–90%), and several mirror reflectivities and gain lengths, laser power (up to 500 kW), efficiency (≲0.4%), gain, threshold conditions, and spectral characteristics have been studied. Laser action was achieved at three wavelengths in the second positive band of N2: 337.1, 357.1, and 380.5 nm. Comparison of the observations with predictions of a model showed that emission at all three wavelengths was expected, and initiation times and pulse durations of the three lines were accurately predicted. Observed similarities and differences between proton beam and electron beam excitation of the Ar/N2 laser are discussed.