Hannover 2010 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 2: Diagnostics

P 2.4: Vortrag

Montag, 8. März 2010, 14:55–15:10, B 305

First Results Of Streamer Formation During Dielectric Surface Flashover At Atmospheric Pressures — •Klaus Frank, Jim Dickens, Lynn Hatfield, Magne Kristiansen, George Laity, Andreas Neuber, and Garrett Rogers — Center for Pulsed Power and Power Electronics, Box 43102, Lubbock, TX 79409-3102, USA

This paper describes some initial results from an experimental setup designed for studying the optical emission during pulsed surface flashover at atmospheric gas pressure for the wavelength range between 115 nm to 180 nm at atmospheric pressures. Typical discharge parameters at atmospheric pressure are a flashover spark length of about 8 mm under a pulsed (thyristor switched) 35 kV, 20 A excitation. Experimental results of streamer formation recorded with a CCD camera ( Andor 734) having a high sensitivity and a good resolution in space and time are presented. One important parameter on which the streamer formation and the subsequent breakdown strongly depends is the gas composition. That is why the streamer formation was recorded for gated intervals from 4 to 50 ns in standard nitrogen, oxygen and purified oxygen and nitrogen. It can be concluded that most of the VUV emission occurs during the streamer formation stage of the flashover event. This is important because it is believed only radiation below 180 nm is energetic enough to cause photoionization leading to the development of a streamer discharge. Since up to now little is known about VUV emission during this initial stage, more time-resolved experiments are necessary.