Scaling and performance of CO2 lasers at supra-atmospheric pressure

In the pressure range 1-5 bar, the performance of a compact UV photopreionized Te laser is studied. It is shown that although the laser pulse shape is little altered as the pressure is increased, the peak power and the total output pulse energy increase significantly with the pressure. The output energy is scaled with the product of the source charge input per unit electrode area and the total molecular partial pressure (CO2 + N2 + CO) which is explained in terms of the pressure-dependent discharge impedance. The optimum laser pressure is limited to 1.5-2.5 bar by an input-energy-related discharge instability, and at constant input energy the instability boundary depends on the molecular partial pressure. Consideration is given to the variation of the pre-ionization photo-electron yield with pressure and to sealed laser operation.