Molecular Radiation From Microwave-Excited High-Pressure Plasmas

This paper explains electrodeless high-frequency power input and plasma behavior in high-pressure lamps. Several lamp geometries and Hg-free lamp fillings were tested. The lamps were made of quartz containing Ar as an ignition gas and several metal halides as light-emitting substances. The lamps were operated in a special cavity configuration at a frequency of 2.45 GHz. The main energy input was varied between 10 and 80 W. Input power, spectral distribution from the ultraviolet to the near-infrared spectral range, and vessel temperature were observed. Variations in the filling, the input power, and the wall temperature lead to changes in the spectral output, color temperature, and color rendering.