Life Projection of Far-UVC KrCl Excilamp with 222nm Peak Wavelength

Abstract

The KrCl Excimer lamps (Excilamps) with 222nm peak wavelength have been developed for 20 years, however, there are few researches found regarding on their life projection. To insure the enough radiation for the important inactivating effectiveness during the service life, this work focuses on irradiance maintenance of KrCl Excilamps at different tube wall temperatures. In general, the activation energy of the Arrhenius equation modelling the lifetime for electronic products suffering from temperature stress below 500K can be considered as temperature-independent. However, due to the unique configuration of KrCl Excilamps without the electrodes inside their tubes and the chemical reaction of Chlorine with the quartz tube wall, their degradation model might need to be verified. In our study, the irradiance of the KrCl Excilamps at tube temperatures around 80, 90 and 100°C for 1000 hours was investigated to find the associated rate coefficients using the exponential and the logarithmic least square curve-fitting. For the better accuracy of life projection, the power-law and the linear relations with temperature are assumed to obtain the temperature-dependent Arrhenius parameters: the pre-exponential factor and the activation energy of the Arrhenius Equation. It is found that the life projection based on the irradiance maintenance can be obtained with a better agreement by the temperature-dependent models using the logarithmic least square curve-fitting for the KrCl Excilamps with 222nm peak wavelength.