Parametric studies of an electron-beam-pumped krypton-rich KrF laser

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Abstract
This paper describes the results of a detailed experimental study of an electron-beam-pumped, high Kr concentration KrF laser. The excitation rate is 1.4 MW/cm3 for 1 atm of Kr gas. The formation efficiency of KrF* and extraction efficiency are estimated using calculated values of saturation intensity and g0/α0, the ratio of small-signal gain to saturable absorption, together with measured values of g0 and the ratio of g0 to nonsaturable absorption (αn). Although the highest formation efficiency of 24% is observed at 99.7% Kr concentration, the effect of finite vibrational-relaxation rate significantly decreases the KrF* density accessible to lasing at high Kr concentration due to the shorter lifetime of KrF*. KrF* vibrational-relaxation rates of 4×10−11 and 5×10−11 cm3 s−1 are determined for Ar gas and Kr gas, respectively. A decrease of g0/α0 and g0/αn resulting in low extraction efficiency is observed at high Kr concentration due to the relatively high α0 and αn. The intrinsic efficiencies are 11, 11.8, and 9% for 1 atm mixtures at 10, 50, and 99.7% Kr, respectively.