Discharge Characterization of Kr/Cl₂ based 222 nm Far UV-C Excimer Radiation Source

In the present work, experiment has been performed for the characterization of dielectric barrier discharge (DBD) based Kr/Cl<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> excimer lamp excited by short unipolar pulse of negative polarity for the effective generation of 222 nm Far UV-C radiation at different operating and geometrical conditions. The production of 222 nm radiation is mainly through the spontaneous decay of KrCl* exciplex from B to X state. The experiment has been performed at different gas composition and pressure in order to obtain their effect on the intensity of 222 nm radiation. The electrical discharge occurred with intense filaments with some background glow for pressure >100 mbar throughout the excilamp while uniform glow is observed at lower pressure. The role of chlorine percentage and total pressure has been analyzed for the emission of 222 nm radiations. The absolute irradiance and the radiative power of 222 nm radiation have also been observed experimentally at different operating parameters. The experimental analysis evaluates that the highest 222 nm radiative power is obtained at 0.5% Cl<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> which remarkably decreases at total pressure of excilamp < 100 mbar. It has been observed that the characteristic emission spectra of the KrCl* excimer source at total pressure of 300 mbar are mainly centered on 222 nm with weak bands of 235 nm and 258 nm.