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We report on an electric discharge laser pulser that used three parallel thyratrons to drive a large, meter -long HgBr laser. By placing a magnetic sharpening switch between the thyratrons and the laser load. we were able to generate a 60 kV voltage,Rpike. and a 30 kA, 120 nS long current pulse with a rising front of approximately 1 x 10 A/S at the laserhead. This led to an optical output exceeding 2 J and an energy transfer efficiency of 1.7 percent. InrsQss.ss.Lt.iQn HgBr lasers are generally considered to fall under the broad category of excimer lasers, and as such pose difficult problems electrically because they require extremely fast -rising. high peak -amplitude voltage and current pulses for adequate performance. Until recently, almost all excimer drive circuits were designed around railgaps, sparkgaps. or thyratrons because they had acceptable single -shot voltage and current switching capability. These switches. however. have often proved inadequate for laser systems that require high frequency and long-life operation. This is because high di /dt requirement in the discharge circuit causes large commutation losses. which in turn leads to unacceptably severe electrode erosion. gas depletion and cathode destruction in the switch. Magnetic pulse compression is a technique that improves switch life by lowering its di /dt requirements, thereby reducing commutation losses and switch damage [1].Magnetic switching for lasers has received much attention recently [2 -4], and the state -of-the -art in excimer drivers presently rests with a spiker and magnetic isolation element circuit arrangement that has produced an efficiency of 4 percent at 2.7 J optical energy in XeC1 [5]. What we report on here is the precursor to the spiker circuit. which. when it was designed and built back in 1982. employed three large parallel thyratrons and a magnetic sharpening switch to drive a meter -long HgBr laser.IhXraLrQn çirrnit ArxanY.gmant.

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