Interferometric investigations of the plasma density in a pulsed electric-discharge $CO_2$ laser

Interferometric measurements were made of the electron and neutral particle densities in the active medium of a pulsed electric-discharge $CO_2$ laser. A Michelson interferometer was used with an $HCN$ probing laser emitting at a wavelength of $337\mu m$. The maximum electron density (about $1,2\cdot10^{12}$ cm${}^{-3}$) was reached in a time of $\thicksim1\mu sec$ and the duration of the current pulse was $\thicksim0,5\mu sec$. Ejection of the gas from the main discharge gap was observed at $40-60\mu sec$ after the discharge, and it reached a value of $\triangle N/N=60-80\%$.