Saturation effects in a continuous-wave HF chemical laser

The multiline performance of a cw HF chemical laser was measured as a function of the SF₆ and H₂ flow rates, cavity losses, pressure and resonator type. The first data from a cw laser for a near-resonant energy transfer from v = 3, J=3,4 to v = 2, J=14 with a subsequent rotational cascade to v = 2, J =11 were obtained. The stable resonator data indicated that the polarization introduced by the Brewster windows affects the power spectral distribution. The amplitude, frequency, and Fresnel number dependence of the time-dependent oscillations which were predicted to occur on lines whose saturated gain does not fill the unstable resonator were measured. The data showed that the oscillations do not occur for Fresnel numbers below 1.5 and that their amplitudes increase as the fraction of the resonator filled by the oscillating lines decreased. The a priori prediction of these characteristics of the time-dependent oscillations by the MNORO3UR computer model was in agreement with the data.