Low-pressure microwave plasma ultraviolet lamp for water purificationand ozone applications

Abstract

Low-pressure mercury lamps are commonly used for germicidalapplications. The germicidal effect is due to the emission of light at 254 nm,which leads to the destruction of the most waterborne bacteria and viruses.The microwave plasma ultraviolet (UV) lamp (MPUVL) is a new technology forgenerating a high-intensity UV light and that can be also controlled tooperate at 185 nm; irradiation is in air at this wavelength produces ozone.The microwave power is injected into a resonant cavity and thesurface wave excitation takes place within the cavity through that part of thedischarge tube (fused silica) protruding inside it. The MPUVL has manyadvantages over conventional lamps, which are limited to an output power inthe region of 30 W m-1, while MPUVL can deliver any amount of power perunit length and the tube can be of any shape, length or diameter. This paperdescribes the design of the MPUVL and compares its efficiency with that ofconventional lamps through spectral analysis. Other results, which include theeffects of temperature and different power inputs, are also discussed.