High‐speed circuits for TE discharge lasers and high‐voltage applications

Pulsed transverse electric (TE) glow discharges used to produce population inversions in gas lasers at 1–20 atm require high‐speed, high‐voltage, high‐current capacitor banks. In this article we first review and compare the circuits in common use to produce the required fast, self‐sustained glow discharges in CO2, excimer, and N2 lasers. The parameters and circuit types given will be useful to future designers of pulsed gas lasers to design and to optimize any proposed circuit in order to yield any desired operating conditions and parameters. The n‐stage circuit types presented are capacitor‐transfer (C‐C), L‐C inversion, Marx bank, and fourfold L‐C inversion, with their double‐sided counterparts, and also their transmission‐line counterparts, such as the Blumlein circuit. A one‐parameter differential equation is developed which describes the general series C‐L‐R circuit. Electrical pulses measured on various lasers are compared with the differential equation solutions for various bank impedances and load resistances. We then present the design and measurements of a new automatically preionized, double‐sided, L‐C inversion circuit for an 800‐mJ, TE CO2 laser, and compare it to previous systems. Methods to lengthen the discharge pulse, and some novel active mode locking techniques are discussed. We compare the L‐C inversion circuit, the fourfold L‐C inversion circuit, the conventional Marx bank, and the ‘‘double Marx bank’’ for lasers and other applications, such as pulsed particle accelerators. Finally, we discuss capacitor bank interconnections, electro‐optic probe systems, and various triggering methods.