UV emissions from an unipolar sub-μs pulsed DBD in He-Air mixtures

摘要

UV emissions from NO,OH,N2,and N2+ between 200 nm and 400 nm from a fast-pulsed DBD in a He-air gas mixture (discharge gap:1 cm,pressure:100-750 Torr,voltage:2.5 –8 kV,sawtooth pulse:decaytime ～10 ns,frequency:1.5 –23 kHz,He air mixture with 3%-30%air)have been investigated.Thedischarge (～10 ns)studied here is ignited when a fast shortening pulse is applied.The main factor thatdetermines the spectral distribution is the amount of air admixed to the He.Because of the importance ofUV emissions around 250 nm in sterilization and biological applications,a calibrated photodiode wasused for absolute intensity measurements of the NO γ-band system in the 200 –280 nm range (～1μW/cm2 at a distance of 6cm from 1cm3 discharge,power input 60 W).