Mach Y stems from spherical shocks: photo investigation of the effects of fractional gram charges

Abstract

An investigation of primary and reflected spherical shock wave phenomena was conducted by center-detonating spherical ¼ gram PETN (Penta-erythritol tetranitrate) charges and photographing the resulting shock waves. This was done at accurately timed intervals in the range of 40 to 1000 microseconds with a Polaroid camera in conjunction with a high intensity xenon flash tube as a light source. Clear and measureable photographs of the primary and reflected shock waves with associated Mach stem formation were obtained over the entire range of investigation. Since this paper represents the first data ever obtained on a laboratory scale of Mach stem phenomena, correlation of spherical shock wave parameters was necessarily made with available theoretical and experimental data by using primary shock wave data. Correlation results were excellent which shows that the Mach stem and other data contained herein are accurate and therefore reliable in determining high yield shock wave parameters by the use of appropriate scaling.