Reach On Discharge Technique Of Non-Chain Pulsed DF Laser

Mid-infrared band, in the spectral range 3~5μm, is the infrared atmospheric transparency window covering the absorption peaks of many atoms and molecules. Besides, the absorptivity of bones and muscles is different in the mid-infrared band. Thus mid-infrared laser has high application value and future in military, laser radar, atmospheric sounding, medical treatment, etc. Currently,non-chain pulsed DF laser has the highest output energy in this band. Furthermore it has the advantages of compact structure, simple operation, controllable reaction, good beam quality, etc. And it receives the domestic and foreign multitudinous researcher’s attention. In this paper, the discharge technique of non-chain pulsed DF laser is studied.Discharge technique is the core technology of the non-chain pulsed DF laser, which determines the output energy and the electro-optical conversion efficiency of the laser directly. In this paper, the UV pre-ionization and the self-initiated volume discharge are compared. Firstly, the electric field distribution of two kinds of discharge modes is simulated by finite element analysis. UV pre-ionization discharge requires using uniform field electrode to increase the injection energy and discharge volume. The electric field distribution of three kinds of uniform field electrode, Chang electrode, compact Chang electrode and Ernst electrode were calculated. At the same design requirements, the area of uniform electric field on the surface of the Ernst electrode is the largest, followed by the compact Chang electrode, and the Chang electrode is the smallest. And then the electric field distribution of the self-initiated volume discharge electrode is calculated. The burrs on the cathode surface will form a series of higher electric field, but not affect the uniformity of the electric field in the discharge area. The strong electric field region of the rough cathode surface not only strengthens the electric field energy of the electron, but also strengthens the field emission of the cathode. There are more electrons in the discharge area relative to the low electric field area, so that the initial discharge channel can be formed.Two kinds of discharge modes of DF laser are studied by experiment, optimizing the output energy of two lasers, compared and analyzed the output energy and the efficiency of electro-optical conversion about two discharge modes of DF laser. The discharge photos of the UV non-chain DF laser are recorded. It is proved that the stable volume discharge can be obtained, and the discharge volume and the injected energy can be increased in the uniform electric field distribution. By analyzing the two discharge modes, it is found that the self-initiated volume discharge has more advantages to enhance the discharge volume of non-chain DF laser.