Studies On The Evolution Of The Working Gas Of Tea Co₂ Laser With Real-time Mass Analysis

Recently, high power pulsed carbon dioxide laser is attracted attention again for the newly application of laser propulsion and optical pumped terahertz laser. Stable uniform glow discharge is the basical mean to achieve a high repetition rate and long-term operation laser. In this thesis, one of the key technologies on stable uniform glow discharge: evolution processes of working gases were studied with real-time mass analysis.Firstly, the basic principles of the vibration excitation processes and decomposition mechanism of carbon dioxide molecules in discharge process were introduced; a variety of commonly used assisted gases which effect laser output energy and working life was listed; producing processes, harm and elimination methods of negative ions in long-term operation of laser were pointed out.Secondly, the structure of quadrupole mass spectrometer and basic principle of quadrupole mass filter were introduced. The operation of mass spectrometers, attentions, three commonly used modes and the set of parameters were summed up. Long-term sampling losses of working gases were experimental study.Finally, the evolution of working gases and changes of output energy of the TEA 30 laser were observed real-time with mass spectrometer and energy meter respectively. Carbon monoxide, hydrogen, and solid catalysts were used to obtain a long-term stable discharge with high power injection. Their effects were analyzed using parameters such as decomposition of carbon dioxide, production rate of harmful gases like oxygen and nitrogen oxide, largest single pulse energy, working life and discharge stability. Comparison results showed that while the use of hydrogen and carbon monoxide catalyst, laser with high single pulse energy and long working life was obtained.