Theoretical And Experimental Studies On The Pyrotechnically Pumped Laser

Redox reaction of chemical materials gives out intense light. Enlightened by this fact, study of matching between pyrotechnic reaction emission spectrum and laser medium absorption spectrum was made and a new prescription of pyrotechnical was prepared based on the study of pyrotechnic reaction radiation mechanism. Pyrotechnically pumped laser was fabricated, and its structure and optical ability were improved. Future application of the laser was studied by comparison with gas discharge lamp and solar pump source.To satisfy the demands of developing effective new pyrotechnic light source, genaral and special experiments on all kinds of oxidant and fuel were made. Relationship beween oxidant, fuel and radiantion intensity, emission spectrum was given out. Burning equilibrium state thermodynamic parameter and producion ingredient of pyrotechnical were calculated by CEA (chemical Equilibrium with Applications) program, and compared with the experiment results. Analysis of radiation mechanism considers that either continuous spectum or line spectra was the result of thermal excitation. They all obey the rule of black-body radiation. Continuouse spectrum was scaled by equilibrium temperature, intensity of line spectra decided by the transient state high temperature of deviated gas. Spectral distribution of line spectra was decided by emissivity of gas. The conclusion is important for apprehension of pyrotechnic reaction emission spectrum and study of pyrotechnic preparation.Formation and influencing factor of pyrotechnic emission outline was analysed because of its significance to the optical pump efficiency of laser. The absorption spectrum of laser medium affected by the actication center and ground substance, so phosphate Nd glass was selected for experiment in the paper after comprehensive consideration of physical, chemical, optical property and technical actuality. A set of prescription which give out mixed spectrum were prepared for the laser medium, they are different completely with the prescription used before. Among them, A# prescription gave out laser steadily. The chemical composition of A# is: RbNO₃, Ba(NO₃)₂, KClO₄, NaNO₃ and Al/Mg.Experiment equipment of pyrotechnically pumped laser was designed and fabricated based on the prescription study. Burning speed, peak radiation intensity and optical efficiency were improved by replacing half of Al/Mg with pulverized Mg powder. In view of the space transmit character of light and obstruction of condensed phase in production, law on laser energy varied with pyrotechnical distribution and weight was studied. It was found even pump is achieved by distribution manner that poles concentrated to few wires and the interval between poles is smaller than the spacing between poles and quartz tube. The best result was: 1.012J laser at 1.053μm which lasting 40ms was achieved by 2.52g pyrotechnical powder.Comparisons with other optical pump source suggest that, the genaral radiation of pyrotechnical pump source is lower than Xe lamp, but the efficiency shouled exceed Ke lamp and alkali metal lamp. In genaral, the pump source corresponds to gas discharge lamp. Pyrotechnical pump source as well as solar pump source is very useful when electric energy dosen't available; former is more expedient and convenient.Based on the study of pyrotechnic optical property and laser structure, method to ameliorate the pyrotechnical pump source wase put forward: improving the burning rate and ignition synchronism to acquire higher peak radiation intensity, and depressing the self-absorption effect to raise the spectrum efficiency and energy conversion efficiency. The fluoride Nd laser ceramic excited with the improved pump source will be a promise scheme to increase the laser energy and peak power greatly.