The influence of oxygen on CO-laser performance

Abstract

Additions of a few parts per thousand of oxygen to a CO-He mixture change drastically the laser output power, the axial field in the positive column, and the slope of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E-I</tex> curve of the discharge. The intensity of the spectrum of vibrational transitions of the CO molecule increases when oxygen is added; the increase is especially pronounced for transitions from higher ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\upsilon &gt; 7</tex> ) levels. The most prominent feature in the visible spectrum is the disappearance of the C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> -Swan bands with the addition of oxygen. The populations of CO vibrational levels were derived from the IR spectra; they increase by more than an order of magnitude for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\upsilon &gt; 7</tex> . The electron energy distribution was derived from measured E/N and the Boltzmann equation. Oxygen affects the Boltzmann equation (and thus the electron energy-distribution function) through the change in E/N, which is in turn determined by ionization and deionization processes. The fractional power transfer from electrons increases to vibrational levels and decreases to electronic levels.