Efforts to obtain reliable performance of the chemically pumped laser were continued. Consequently evaluation of the coaxial coupling geometry was initiated during this reporting period. The axial extent of the reflected shock heated xenon, which serves as the pump source, was determined from measurements of relative radiation intensity and found to be significantly less than that calculated from analysis of the ideal shock tube flow. The reduction of length of the hot gas slug has been attributed to excessive mixing between driver and driven gases. Further evidence in support of this explanation will be obtained from spectroscopic observation of the shocked gas flow. Modifications which can be expected to stretch the length of the gas sample have been examined analytically and several, involving area changes in the shock tube, will be studied experimentally.