FRAGMENTATION AND EMISSION OF POPOP AND COUMARIN DYE VAPOR IN AN ULTRAVIOLET PREIONIZED, TRANSVERSE DISCHARGE

Intense, streamer-free discharges have been produced in POPOP (1,4-di[ 2-(5-phenyloxazolyl)]benzene), alpha-NPO (2-(alpha-naphthyl)-5-phenyl- oxazole), PBBO (2-(4-biphenylyl)-6-phenylbenzoxazol-1,3), and coumarin dye vapors buffered in He or rare gas/N-2 mixtures. The transverse di scharge has an equivalent series inductance of similar to 85 nH, a cur rent rise time of similar to 50 ns, a pulse width (FWHM) of similar to 140 ns, and active lengths up to 50 cm. For specific power loadings o f rare gas/POPOP vapor mixtures ranging from 2 to similar to 11 MW cm( -3), the wavelength-integrated fluorescence falls to 50% of its initia l value after 150-200 shots (at similar to 620 K) and emission bands o f CN and C-2 appear. Under comparable conditions, the fluorescence eff iciency of alpha-NPO is only 40% of that for POPOP vapor. The coumarin dyes are considerably less stable than POPOP and strong fluorescence on the Swan bands of C-2 is observed after only a few shots. Net optic al loss is measured when Ne/N-2/POPOP vapor discharges are probed with a dye laser at similar to 400 nm.