HEAVY-ION BEAM-PUMPED LASERS - OPTICAL GAIN ON THE 476.5-NM AR-II TRANSITION

The possibility of heavy-ion beam-pumped ion lasers is demonstrated by observation of optical gain on the 476.5-nm Ar II 4p-4s ion laser tra nsition in argon gas excited by 2.5-ns pulses of 110-MeV S-32 ions wit h repetition rates up to 156 kHz. The particle energy per pulse was ab out 20 muJ. The projectiles were stopped in the target at pressures be tween 5 and 35 kPa. The beam from an argon ion probe laser operated at 476.5 nm was used to determine gain amplitude and time structure from a measured transient increase of the probe laser intensity when targe t excitation by the ion beam was present. The maximum gain observed wa s (0.5 +/- 0.1) X 10(-3) at a target gas pressure of 5 kPa. The optica l gain observed in argon is consistent with calculations based upon an analysis of spectroscopic studies of rare gas targets excited by heav y-ion beams.