Radiation characteristics of coaxial KrBr* excilamps based on a dielectric barrier discharge

The characteristics of the emission spectra of coaxial KrBr* excilamps driven by sinusoidal, rectangular and pulsed electronic control gear (ECGs) are investigated, based on the dielectric barrier discharge (DBD) with an annular gap of 10.5 mm. The radiant power of intense narrow band ultraviolet radiation at 207 nm is derived from the irradiance according to the Keitz formula, while the input power is computed from the integral of the product of voltage and current. The radiant characteristics of the 207 nm spectral line have been studied with regard to total pressure and bromine percentage, demonstrating an optimum pressure at 300–350 mbar as well as an optimum bromine percentage 0.1–0.3%, resulting in (3–4%) ± (0.3–0.5%) radiant efficiency at the optimum lamp power density of 360–540 W m−1. Of the three ECGs, results indicate that the pulsed waveform produces a higher efficiency than rectangular and sinusoidal waveforms. (paper)