Explosive Testing of High-Pressure Vessel for Proton Imaging of Shock Physics Experiments

Abstract We present the results of explosive testing of an Inner Pressure Confinement Vessel (IPCV). The IPCV is explosively-loaded high-pressure vessel which is a part of the containment system to facilitate proton imaging of small-scale shock physics experiments at Los Alamos National Laboratory (LANL). The detonation of high explosive (HE) drives material to extreme loading conditions, which are imaged using a proton beam and an imaging system. The IPCV needs to satisfy the ASME Boiler and Pressure Vessel Code, Section VIII, Division 3, Code Case 2564, while allowing for maximum resolution of proton radiography. The IPCV contains an Experimental Physics Package (EPP), fragment mitigation assembly, and radiographic windows. To achieve the optimal imaging resolution, the radiographic windows need to be very thin, located extremely close to the HE, and made of low-attenuating material such as Beryllium. While the IPCV is designed to a relatively small HE amount of 30 g TNT equivalent, the radiographic window is located only a few cm away from the HE, which is unique to this specialized high-pressure vessel. Fragment mitigation is critical to protecting radiographic windows from any fragments to allow the IPCV to maintain the pressure boundary before and after the explosive experiment. This shielding contains two layers: Boron carbide (B4C) facing the HE and Dyneema (cross plied composite layers made of ultra-high molecular weight polyethylene) facing the window. The B4C plate serves to break up and dull fragments while Dyneema catches fragments and prevents them from contacting the radiographic windows. Design development of the fragment mitigation assembly and attachment was informed by several series of explosive tests at LANL. The tests also addressed the sealing function of vessel covers, gas lines, and isolation valves before and after an explosive experiment.