Caxial Microwave Discharge Lamp of Aluminum Coated Quartz Glass Tube

Caxial microwave discharge (CMD) lamp has been developed for UV light source. To extend the length of microwave plasma in the discharge lamp, a novel structure of microwave discharge lamp has been developed. The microwave plasma was produced in a thick quartz tube by traveling wave along a coaxial line consisting of a central plasma rod as the inner conductor itself and the Al coating on the tube surface as the outer conductor. A thin slit was opened on the outer conductor of Al coating along the tube to extract the emitted light. The microwave plasma length was extended more than 75cm at 150 W of microwave power. Peak emission intensities showed gradual decay with the traveling distance of the microwave from the end while the white band emission originated from recombination showed rapid decay from the excited end. Emission profile along the lamp was almost uniform when the microwave was supplied from both sides alternately.