Maximizing the efficiency of a compact helium-free TEA CO2 laser: Experimental results and theoretical simulation

Abstract

The design, development and operational characteristics of a compact corona pre-ionized helium-free TEA CO2 laser is discussed. Remarkably high efficiency of about 19% was obtained in this laser, which is attributed to the optimum concentration of CO2 and N2 gas, reduction in energy dissipation in the pre-ionization loop and the switch, minimizing the diffraction losses and finally optimization of the output coupler reflectivity. The helium-free TEA CO2 laser has also been analysed using a comprehensive theoretical model, developed based on the Boltzmann transport equations and the discharge excitation circuit equations. The voltage and current waveforms of the pulsed discharge were simulated and used as input to the laser rate equations to estimate the laser pulse energies and the pulse shapes. The theoretical estimations of the laser pulse energy agree fairly well with the experimental results. The accuracy of our theoretical model becomes evident from the numerically evaluated laser pulse shapes, which show remarkable resemblance with the experimentally measured pulse shapes. A detailed comparison with the helium-rich case is included to highlight the key aspects of a suitably designed helium-free TEA laser.