Time-resolved spectra of high-current pulsed argon lasers

The time-resolved laser spectrum of a pulsed argon discharge has been examined in the visible region with a fast response photodiode and with an image converter camera in the streak mode. At 10 mtorr pressure of argon, laser action takes place on up to eight lines between 4579 and 5145 Å, seven of these lines being
4p \rightarrow 4s
transitions and one a
4p' \rightarrow 3d
transition. With peak discharge currents of 50 to 1500 amperes (400 to 12000 amperes-cm
^-2
) and duration of about 2 μs, laser action takes place both during the current pulse and in the afterglow. The primary laser output occurs during the first half of the current pulse, while the current is increasing, and then laser action ceases until the current has ceased to flow. In the afterglow, laser action recommences and lasts for up to 60 μs. The effects of variation of gas pressure, applied potential difference, and current pulse length on the threshold conditions, intensities, and duration of the lines are examined.