The Characterists Of The Krypton-Halogen Excilamps

The paper reports a systematic study of the coaxial KrCl* and KrBr* UV excilamps, focusing on the effects of voltage and current waveforms, wall thickness and gas parameters on lamp parameters. Accordingly, the optimized discharge parameters are determined.The spectrum, input power and 222 nm radiant efficiency were measured for coaxial KrCl* excilamps based on the dielectric barrier discharge (DBD). The inner tubes of the lamps have inner/outer diameter (ID/OD) 14/16 mm. The OD of outer tubes is 40 mm with wall thickness 1.2,1.5 or 2.0 mm. The total filling pressure is 200 mbar with chlorine 2 mbar and krypton 198 mbar. The lamps are driven by sinusoidal, rectangular and pulsed electronic control gears (ECGs). The 222 nm radiant power is derived from Keitz formula with irradiance measured. The input electric power is measured with an oscilloscope, combined with a voltage probe and a current probe. The results show the maximum efficiency of 222 nm radiation is 9.2% for a KrCl* excilamp with wall thickness 1.2 mm, driven by a pulsed ECG. The effects of waveform, input power, wall temperature and transmittance of the tube are discussed. The variation of micro-discharge filament configurations at different voltage waveforms is observed. Moreover, the uncertainty of input power and irradiance is analyzed.Through changing the gas component of KrCl* excilamps, such as total pressure and chlorine percentage, the optimum parameters are determined. The results show that for a KrCl* excilamp driven by pulsed ECG, the highest efficiency reaches 11.4% when the total pressure is 200 mbar with chlorine percentage around 0.5%. The FWHM (Full Width at Half Maximum) will decrease with increasing total pressure, but it depends slightly on the chlorine percentage.The spectrum, input power and 207 nm radiant efficiency are also measured for coaxial KrBr* excilamps based on DBD. The lamps were driven by sinusoidal and pulsed ECGs. The 207 nm radiant power is also obtained with Keitz method. The input electric power is calculated with the integration of the product of voltage and current and with the Lissajous figure. And the former method yields higher accuracy. The results show that for a KrBr* excilamp driven by pulsed ECG, the highest efficiency reaches 2.2% when the total pressure is 300 mbar with bromine percentage around 0.25%.