Arc-discharge monitoring system of a high-power repetitively-pulsed TEA CO2 laser

Abstract

High-power repetitively-pulsed TEA CO2 lasers are excited by a glow discharge, and it turns out to be the arc discharge under some conditions. The arc-discharge is a disadvantageous condition and must be avoided. According to the Faraday electromagnetism induction principle, the arc-discharge monitoring system with a magnetic-field probe is designed for high-power repetitively-pulsed TEA CO2 lasers. The magnetic-field variation induced by the discharge current can be tested, and the discharge state can be distinguished according to the output induction voltage. Experimental results show that the magnetic-field induction voltages generated by a glow discharge and an arc discharge are very different ones. The maximum induction voltage of the glow discharge is 2.0 V, while the minimum induction voltage of the arc discharge is 2.5–4 V. Three alarm levels are set by measuring the arc-discharge intensities. At the first level, automatic filling–exhausting equipment starts to refresh the gas media, at the second level, the laser repetition rate is reduced, and at the third level the laser operation stops immediately. As a result, the working reliability of a high-power repetitively-pulsed TEA CO2 laser system can be improved significantly by using the arc-discharge monitoring system.