A high power density (greater than 1,000 W/cc) microwavedriven plasma source has been developed, and it can potentially be an efficient vacuum ultra violet (VUV) light source. This assessment is based upon previous spectroscopic measurements and power balance analysis of steam plasmas created at atmospheric pressure with only 6 kW of power. A new UV light source with high power below 200nm which can be potentially applied to photolithography and surface treatment of polymers is being developed in this research.Commercial Applications:This new class of light source can be potentially applied to photolithography, and surface treatment of polymers.