A versatile microwave plasma source and its application for a CO2 laser

Abstract

A single ridged waveguide with nonconstant ridge height, operated with a traveling wave has been proven to be a versatile microwave plasma applicator. Easy dimensioning, inexpensive production, and compatibility to standard rectangular waveguide components are the main advantages compared to other designs. The described plasma source is especially suitable for any applications where an exceptionally uniform plasma is required. Design equations are given for easy adaption of the applicator to individual requirements. The applicator has been investigated for microwave excitation of a diffusion-cooled CO2 laser. With a nonoptimized system, laser output power of 9 W could be achieved in a quasi-cw mode. A traveling discharge operating mode is described which is useful for plasma diagnostics and for pulsed laser applications.

Longitudinal coupled‐cavity scheme for microwave‐excited CO2 slab lasers

“…A TM 010 cylindrical resonant cavity was employed in a different setup, as presented in [4]. März and Oestreicher developed a plasma source [5], in which a homogeneous discharge field was formed in a traveling-wave tapered-ridge waveguide using a resistive microwave termination. Radial microwave-discharge homogeneity in a cylindrical laser was implemented by combining orthogonal electric fields in intersecting rectangular waveguides [6].…”