Investigation of Factors Influencing the Character of the Spectrum of a Laser-Induced Plasma

摘要

This is a continuation of earlier work dealing with the plasma flare produced when a laser beam is focused on a substance, and particularly with the effect of the laser energy, the beam focusing, the pressure of the atmosphere surrounding the investigated sample, and the properties of the sample itself on the character of the plasma. The present article is devoted to the influence of the same effects on the spectral characteristics of the plasma. The tests were made by focusing the emission of a GSI-1 laser, operating in the free-running mode on the surface of metallic samples. The variation of the intensity along the plasma flare was determined by projecting the image of the flare on the slit of an ISP-22 spectrograph. At atmospheric pressure, the intensities of the spectral lines increased rapidly with increasing distance between the plasma flare and the surface of the sample, reaching a maximum at distances that depended on the excitation energy.