A simple spark-gap light source together with an associated pulsing circuit has been utilized to produce light flashes of approximately 10<sup>-7</sup>-sec. duration suitable for the study of shock waves produced by high speed bullets and for the photography of shock and turbulent disturbances in supersonic air streams.
J. W. BEAMS, A. R. KUHLTHAU, A. C. LAPSLEY, J. H. MCQUEEN, L. B. SNODDY, and W. D. WHITEHEAD, JR., "Spark Light Source of Short Duration," J. Opt. Soc. Am. 37, 868-869 (1947)