Flat-top, Ar-Xe laser pulses at 1.73 ,um have been achieved by pumping the laser medium with a constant-current electron beam for pulse durations of up to 2.5 ms. The 220 keV electron beam pumped an active volume of 50X 8X6 cm3 at power loadings of 6-100 W/cm3. Small signal gain, saturation flux, and nonsaturable absorption were determined as a function of Xe concentration, total gas pressure, and pump power density by a Rigrod analysis. In the experimental regime investigated, the small signal gain increased as the total laser pressure decreased and as the partial pressure of Xe decreased. The Xe concentration was varied from 0.5% to 2.0% and the total pressure was varied from 250 to 860 Torr. The results are consistent with Xe quenching of the upper laser level being the dominant deexcitation process and with the collisional broadening dominating the linewidth. The peak intrinsic efficiency observed was 2.2%
