Light Intensity from Detonating PETN Pressings filled with Butane

Abstract

SEVERAL years ago it was shown¹ that the luminosity from a shocked bed of granular sodium chloride depends only very slightly on the nature of the interstitial gas, even though it is clear^2,3 that the temperature of two gases with very different properties, shocked to the same pressure, will differ by several thousand degrees centigrade over a wide range of shock strengths. This independence of the luminosity in a shocked pressing of an inert substance was presumed to apply also to detonation waves in pressings of granular explosives, an extrapolation which can be inferred from evidence presented by Paterson⁴. On the other hand, in Plate X of Taylor's book on condensed explosives⁵ a non-time-resolved slit picture is reproduced which shows very different luminosities from three different sections of a PETN charge filled individually with butane, air, or argon. That experiment, performed by I. G. Cumming, leads to the conclusion⁶ that the luminosity in question results from shock compression of the interstitial gas. The apparent contradiction between the two experiments should be resolved, since the dependence or independence of the luminosity on the interstitial gas may have an important bearing on the mechanism of the primary stage in shock initiation of granular explosive charges.