Experimental study of new microwave cavities to produce plasmas and free radicals to initiate chemiluminescences

Two microwave cavities operating at 2450 MHz for producing and maintaining plasmas are described. They have been tested in nitrogen, argon and hydrogen. Cavity I can be used for discharges in nitrogen between 30 mu Torr and 230 Torr, in hydrogen between 30 mu Torr and 640 Torr and in argon between 30 mu Torr and 990 Torr. Cavity II with the same gases can be used between 30 mu Torr and 500 Torr, between 30 mu Torr and 760 Torr, and between 30 mu Torr and 1500 Torr. No experiment has been made at a pressure lower than 30 mu Torr. Cavity I is very easy to handle and the stability of its discharge makes it an attractive source of free radicals to initiate chemiluminescences in kinetic studies.