Acoustic waves and heating due to molecular energy transfer in an electric discharge CO laser
This paper summarizes analytical studies and the interpretation of experimental results for the compression and rarefaction waves generated in the cavity of a pulsed CO electric discharge laser. A one-dimensional analysis of acoustic waves is applied to a transversely excited laser. The influences of heating in the cathode fall, heat transfer to the cathode, flow through both the anode and cathode, and bulk heating of the plasma are included. The analysis is used to relate the bulk heating rate to observable features of the pressure and density waves. Data obtained from interferograms and reported elsewhere are used to infer the bulk heating rates in a pulsed CO laser. Results are presented for CO/Ar, CO/N2, and N2 plasmas. Comparison of the data with recent theoretical results for the heating due to electron/ neutral collisions and the anharmonic defect associated with V-V energy transfer shows substantial differences at lower values of total energy deposition. The change of heating with E/N is in fairly good agreement with predicted values.
© 1976 IEEE. Reprinted with permission. Manuscript received January 26, 1976; revised June 1, 1976. This work was supported in part by the Advanced Research Projects Agency of the Department of Defense and monitored by the Office of Naval Research under Contract N0014-72-C-0043. The authors thank Dr. W.B. Lacina for informative discussions, and for providing results of his calculations.