Experimental investigations of laser parameters in fast-axial-flow rf excited CO2 discharges with different cross sections

Fast axial flow rf-excited discharges ((nu) rf equals 13.5 MHz) in tubes with rectangular cross sections and plane electrodes have been investigated. Probing the tubes on-axis the dependence of small signal gain as well as saturation intensity on the input power density is identical for all the different cross sections. Under equal conditions the small signal gain profiles revealed significant decrease in the vicinity of the side walls with increasing tube dimensions. This is attributed to the change of discharge behavior with increasing interelectrode discharge length. It was found that the critical pressure for the onset of filamentation is reciprocal to this dimension. With this geometrical dependency the laser power of axial flow rf-excited discharges is not volumetric scalable in a straightforward way.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.