The Numerical Simulation Of Chemical Oxygen-iodine Laser Initiated By Pulsed Discharge

Compared with Continuous Wave Chemical Oxygen Iodine Laser (CWCOIL), Pulsed Chemical Oxygen Iodine laser (COIL) not only has the traditional advantages but also has many unique properties, for example, the laser penetrates deeper depth, faster volicity; higher-energy pulsed laser can do efficient Raman frequency shift, then make the wavelength of the laser with a variability and so on. Because of these advantages, pulsed COIL attracting US, Russia, China, Japan and many other countries of researchers engaged in the research of related aspects. There are many ways to achieve pulsed oxygen-iodine laser, through a plused discharge to instantly generate iodine atom to achieve the pulse mode is the optimal and promising. However, until now the related experimental studies focus on the observations under different external parameters, lacking for the study of the key respect of producing pulse laser, which has a certain blindness. Relevant theoretical modeling work is very few, only Kochetov et al, but their simulation uses a zero-dimensional model, so details of the generation and disappearance of different particles can not be given, and this information is critical for discharge initiation COIL.In this paper, we develop a hybrid computational model of fluid and kinetics to study pulsed discharge occurring in the laser cavity of the pulsed COIL. The study includes two parts, the first part is the electric characteristics of the CF3I-O2-O2(a1△g)-He discharge, mainly studies the characteristics of voltage and current, particle density distribution and the discharge mechanism. The second part studies the effects of different parameters (for example applied voltage、pulsed width and mixture ratio of gas) on the density of iodine atom and laser efficiency. Research results are expected to provide a theoretical guide for the control and optimization of pulsed COIL excited by a pulsed discharge.The simulation results show that the pulsed discharge in CF3I-O2-O2(a1△g)-He mixture has the glow-plasma features with the sheath region and the bulk-plasma region. Iodine atom is produced mainly through the collision dissociation process of electron with CF3I. By stydying the discharge parameters on the iodine density we can find that iodine atom density increases with the pulsed voltage amplitude and pulsed width. It is found that keeping total pressure and oxygen partial pressure unchanged, there exists an optimum ratio of CF3I:He, at which the highest iodine atom density and the lowest energy cost are achieved. Under simulation conditions, I atom concentration decrease with increasing total operation pressure. At constant total pressure and oxygen pressure, when content of singlet oxygen is lower than 40% of total oxygen pressure, the population inversion cannot be formed.