Studies On The Discharge Characteristic And Power Supply Of TEA CO₂ Laser

Much higher specifications on pulse energy, peak power, repetition ratio of a TEA (Transversely Excited Atmospheric) CO2 laser are required by the newly growing applications such as laser propulsion, opto-electronic countermeasures, and strong-field physics, etc. The performances of pulse discharge and power system of the TEA CO2 laser are crucial to these requirements.In this thesis, the effects of gas component, gas pressure, working time, repetition rate and resonant cavity parameters on the discharge characteristic and electro-optical efficiency of a TEA CO2 laser are studied experimentally at first. An optimized helium-free gas mixture CO2:N2:H2=1:5:0.67 is obtained, by which the pulse energy is increased greatly and the operation cost is lowered distinctly.Then, the discharge circuit, charge power supply and trigger controller of the power system, as well as their influences on the discharge of a TEA CO2 laser are studied theoretically and experimentally. A numerical model for the discharge processes of the TEA CO2 laser with a charge-discharge-circuit including charge inductor is developed, in which the discharge circuit and the discharge zone are considered in detail. The whole temporal evolution of discharge process is simulated accurately and the role of circuit parameters is discussed.Due to the judgment that the rudimental voltage oscillation after the main discharge existed in the charge-discharge-circuit including charge inductor is a main reason for the glow-arc transition, three methods are carried out: increasing the inductance of the charge inductor, replacing the charge inductor by a high voltage diode stack, and using a Marx high voltage pulse generator. By the Marx generator discharge circuit, the stable working gas pressure and discharge voltage are improved to a high level without changing the charge power supply and preionization system. The resonant charge scheme is studied to overcome the low efficiency and low repetition rate caused by the resistor ballasted voltage source capacitor charging power supply. And a trigger controller is developed based on a single chip microcomputer to improve the operation interface.At last, the temporal waveform of laser pulse is measured by a photon drag detector and the effects of some factors such as gas component and discharge parameters on the temporal waveform are discussed simply. The research results obtained in this thesis, helium-free gas mixture and Marx generator discharge circuit, have been applied in the reform of the TEA-50 laser in the laboratory. The pulse energy of this laser is largely increased, whose maximum reaches 115J.