Spectroscopic and kinetic behaviour of a pure krypton dielectric barrier discharge

This paper deals with the spectroscopic and kinetic study of spatially stable mono-filamentary dielectric barrier discharges (MF-DBDs) occurring in pure krypton between 100 and 500 Torr, by using a high voltage sinusoidal supply. In our experimental conditions, the supply current was constituted of a short fast-rising pulse superimposed on a slow non-dissipative displacement component. For the spectroscopic measurements triggering was carried out with the current pulse. The emission spectra of the MF-DBD show a strong vacuum ultraviolet (VUV) emission at 148 nm. This emission is attributed to krypton excimers Kr₂[1_u(³P₂)] correlated to the lowest metastable atomic state Kr(³P₂) and its intensity increases with pressure, due to the enhancement of 3-body collisions. Since time origin was well defined, the temporal evolution of the excited species could be analyzed. The kinetic analysis of the 2 continuum of krypton was performed by using a suitable VUV detector working in the photon counting mode with a time-resolution of 5 ns. After a brief excitation phase, not exceeding about 80 ns, this emission could be correctly fit by a sum of 2 exponential terms only. The pressure variation of each decay frequency was analysed, and the radiative lifetime Kr₂[1_u(³P₂)]_low and the 3-body collisionnal formation rate constants of the Kr₂[1_u(³P₂)] excimer were estimated. Our results are consistent with those obtained with selective excitation of the lowest metastable state of krypton.