Comparative study of spark pin-array and printed circuit board surface plasma pre-ionization systems for transversely excited atmospheric CO₂ laser performance

Abstract

The performance of a homemade transversely excited atmospheric CO2 laser, capable to be alternatively run using UV spark pin-array (SPA) and printed circuit board (PCB) surface plasma pre-ionization systems, is comparatively studied. The pin-array configuration is comprised of two rows of 5 mm spark gaps symmetrically located on either side of the discharge volume. The surface plasma pre-ionization system consists of a PCB of which, one side is patterned with isolated millimeter size circular pieces. The performance of both types of pre-ionization in different working conditions was experimentally investigated and the output energies were compared with each other as well as the simulation results based on the six-temperature vibrational-rotational model. It has been found that the SPA system provides better discharge stability and uniformity with higher output energies, while using the PCB surface plasma configuration allowed the laser to operate with higher gas lifetime and lowered the need for helium in its gas mixture.