During the operation of the magnetically gain-switched chemical oxygen-iodine laser (MGS-COIL), the transition intensity of hyperfine transition line 2-2 can exceed that of line 3–4, which is the dominant line at zero magnetic field. For this reason, a simulation model including both 3–4 and 2-2 transition lines is necessary to describe the mode buildup process in MGS-COIL. In this paper, we assume that 3–4 and 2-2 transition lines simultaneously oscillate in laser cavity. The propagation of optical field is calculated based on FFT. The required frequency, rise time and residual field of the magnetic gain-switch for a high-performance MGS-COIL are analyzed based on simulation results.
