The Numerical Simulation Of Singlet Oxygen Generated By RF Discharge Of He-O₂

Chemical Oxygen Iodine Laser(COIL)has attracted considerable interest since it was first demonstrated in 1978.Its high laser power with the wavelength m315.1 ? makes it has great advantage in many applications.The COIL operates on the spin-orbit transition of atomic iodine and the population inversion on this transition is generated and maintained by a resonance energy transfer between singlet oxygen and iodine atoms.Therefore,how to generate singlet oxygen effectively becomes especially important.In the traditional COIL system,singlet oxygen was generated by chemical method.This method to get singlet oxygen has the following obvious characteristics: gas-liquid reaction rate is very fast;the life of singlet oxygen is very short;the water vapor resulting from reaction results in the excited state iodine atoms quenching seriously;the gases used in the reaction such as chlorine,hydrogen peroxide and alkali are toxic,strong corrosive and explosive,and will cause environmental pollution.Generating singlet oxygen by discharge is seen as a most promising method and has been investigated widely in recent years.In this paper,we develop a hybrid computational model of fluid and kinetics to study the generation mechanism of singlet oxygen by RF gas discharge.The results of simulation show that the process of excitation collision between electron and oxygen directly for producing singlet oxygen plays a very important role.About 60 %singlet oxygen are produced by it when discharge reaches stable state.singlet oxygen consumption channels are changeable.At the beginning,when there are a large number of oxygen anion in the space,singlet oxygen collides with it mainly to product some other oxygen particles.And in stable stage,it is consumed by a collision decomposition reaction between singlet oxygen and electron and this reaction plays the leading role finally.About30 % singlet oxygen are consumed by this reaction.Thus,we can improve the production rate of singlet oxygen by increasing the proportion of oxygen,but too much oxygen can also lead too much oxygen anion which quenching singlet oxygen seriously.Therefore,there is an optimal ratio exist between oxygen and helium that can generate singlet oxygen with a greater efficiency.Under simulation conditions the optimal ratio is 1 : 4,at which we can get singlet oxygen with the highest efficiency.Keeping the ratio of the helium and oxygen unchanged,we also studied the case with the changeable parameters,like frequency and amplitude of the voltage.