Calibration and diagnostic techniques for VUV plasma lasers

Absolute intensity calibration and plasma diagnostic techniques have been developed for vuv and soft x‐ray lasers that will use a highly ionized plasma as the gain medium. The apparatus is portable and self‐contained, and in situ measurements can be made on a variety of plasmas. The techniques have been successfully applied to a Nd:glass laser‐produced carbon plasma in which population inversions among the excited levels of the hydrogenic C5+ ion have been previously been observed. Using the width and absolute intensity of the C5+ (n=7→) line at 343 nm wavelength, the electron and excited‐state ion densities are measured as functions of time and distance from the carbon target. The gain coefficient for the n=4 → 3 transition at 52 nm wavelength is inferred from the bound‐state density measurements, and the dependence of this gain coefficient on the intensity of the Nd:glass laser is also determined.