An advanced kinetic model of electron-beam-excited KrF lasers including the vibrational relaxation in KrF*(B) and collisional mixing of KrF*(B,C)

Abstract

Computer models developed so far on electron‐beam‐excited KrF(B–X, 248 nm) lasers that include the vibrational relaxation process in the upper lasing B level at the finite rate could not predict the high intrinsic laser efficiency which was experimentally reported. This is attributed to the reduction of the laser extraction efficiency. We have developed a four‐level KrF laser model that includes the vibrational relaxation process and also the collisional mixing of the KrF*(B) and the KrF*(C) levels. The collisional quenching rates for KrF*(B,C) that we used and the vibrational relaxation rate were carefully estimated by using the effective spontaneous lifetimes for KrF*(B,C). As a result, the model prediction was in quite good agreement with many experimental results for a saturation behavior of KrF*(B–X) fluorescence, for small‐signal gains, for small‐signal absorptions, and for intrinsic efficiencies. Estimated rate constants in this model for the vibrational relaxation and the KrF*(B,C) mixing are 4×10⁻¹¹ and 5×10⁻¹⁰ cm³/s, respectively, for a two‐body collision rate with argon gas.