We have recorded short exposure images of visible and vacuum ultraviolet (VUV) emission from a Xe dielectric barrier discharge lamp, and investigated the effects of excitation by fast rising pulse and sinusoidal voltage waveforms on the discharge structure. The images from the pulsed discharge are essentially uniform over the active electrode area unlike the sinusoidal discharge which is filamentary. By investigating a single filament discharge, it is also found that a large fraction ({>}90%) of the total visible and VUV emission for sinusoidal excitation is generated from regions outside the filament. The images suggest that the VUV is generated from surface discharges, or `feelers', which branch out laterally from the filaments. Model calculations suggest that surface or volume discharges, in which the current density is much lower than for filamentary discharges, generate VUV emission more efficiently due to the reduced rate for multi-step electron excitation of Xe* species.
[1]
Richard P. Mildren,et al.
Enhanced performance of a dielectric barrier discharge lamp using short-pulsed excitation
,
2001
.
[2]
Baldur Eliasson,et al.
Dielectric-Barrier Discharges. Principle and Applications
,
1997
.
[3]
Ulrich Kogelschatz,et al.
UV excimer radiation from dielectric-barrier discharges
,
1988
.
[4]
Gerhard J. Pietsch,et al.
The development of dielectric barrier discharges in gas gaps and on surfaces
,
2000
.
[5]
M. Neiger,et al.
Some Properties of a Novel Far UV Xenon Excimer Barrier Discharge Light Source
,
1995
.