AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2-WeA

Paper PS2-WeA6
Miniature Microwave Plasma Torch Applicators and Characteristics

Wednesday, November 5, 2003, 3:40 pm, Room 315

Session: Atmospheric Plasmas & Micro Discharges
Presenter: T.A. Grotjohn, Michigan State University and Fraunhofer Center for Coatings and Laser Applications
Authors: T.A. Grotjohn, Michigan State University and Fraunhofer Center for Coatings and Laser Applications
K. Hemawan, Michigan State University
S. Zuo, Michigan State University
J. Asmussen, Michigan State University and Fraunhofer Center for Coatings and Laser Applications
Correspondent: Click to Email
The experimental evaluation of two miniature microwave plasma torch applicators that have potential use in materials synthesis and surface treatment are described. The first applicator employs an open ended coaxial structure with the discharge located at the tip of the center conductor. The discharge is formed at atmospheric or slightly below atmospheric pressure where the feed gas flows through the center conductor of the applicator. The second applicator is similar to a microstripline coupling structure described earlier.@footnote 1@ This applicator couples microwave energy to a surface wave discharge formed in an open ended tube placed between and perpendicular to the strip transmission lines. The feed gases are fed directly through the surface wave discharge and flow out to a pressure controlled environment ranging from approximately 10 Torr to atmospheric pressure. Both microwave plasma torches are experimentally evaluated over a range of input power and a variety of feed gas mixtures including argon, mixtures of argon with hydrogen and selected hydrocarbon gases, nitrogen, and air. These torches operate from 10’s to 100’s of watts of input power and are able to maintain discharges over a wide range of flows from diffusional flow of radicals for gentle surface processing to high velocity flows approaching supersonic velocities. Objectives of this work are to create compact microwave plasma torch designs that operate from below atmospheric pressure to one atmosphere pressure with processing spot sizes ranging from several mm down to less than 0.25 mm. The numerous applications of these microplasma torches include cutting, welding, cleaning and other surface treatments. @FootnoteText@ @footnote 1@ T. A. Grotjohn, et.al., "Characteristics of Miniature Microwave Excited Plasma Discharges," AVS Symposium, Denver, 2002.