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VOLUME 60 (1994) | ISSUE 1 |
PAGE 11
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Effect of intense UV flashes from laser discharges in gases: observation of a fast-rising photodissociation halo leading a shock wave
Askar'yan G. A., Korolev M. G., Korchagina E. G., Yakushkin K. L.
The photodissociation of gases near intense laser sparks have been studied experimentally. The power and flux density of UV light have been estimated. It is shown on the basis of the results that the "kern" of the breakdown is an intense source of UV light, in fact, a source with a record-high flux density. It is also shown that over a short time, on the order of the length of the laser pulse, a new physical effect is observed: a fast-rising halo of intense photoionization of the gas. This halo leads the shock wave and generates its own shock wave. It is shown that there is a bleaching of the media for UV light because of intense photodissociation and photoionization. Chlorofluorocarbons are used as examples to demonstrate the fate of polyatomic impurities in a background gas subjected to UV light. Some new possibilities for removing harmful pollutants from the atmosphere by means of new sources of UV light (excimer lamps and the radiation from lasers, laser sparks, and laser plumes) are discussed. An analogy is drawn between the effect of the "kerns" of laser sparks and that of the streamers of microwave discharges.
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