Development of pulsed pressure vessels for high-pressure dense plasma experiments: analysis and early experiments

The study of warm dense matter, having temperatures upto tens of thousands of degrees and pressure upto 1 GPa, requires confinement of such plasmas inside a pulsed pressure vessel. The confinement must be for a period of hundreds of hundreds of μsec to permit property measurements under near-uniform conditions. Hence it is necessary to develop pressure vessels that can withstand hundreds of MPa internal pressure as well as high heat- fluxes. If the plasma is produced by electrical discharges, it is additionally necessary to have high-voltage compatibility. Pressure vessels subjected to quasi-static loading can be designed as per well established ASME codes. However theoretical and experimental investigations of vessels subjected to pulsed loading are limited. Here, the loading duration is much less than or comparable to the fundamental response of the vessel and therefore requires consideration of inertial effects, usually neglected in case of static loading. A novel experimental set up has been developed for carrying out pulsed loading of pressure vessels. A metallic foil is taken from solid to Warm Dense Plasma regime via passage of a pulsed high electrical current. As a first step, by varying the foil mass from 42mg to 105mg, peak pressures of few MPa have been generated in a controlled reproducible manner in a closed volume. A piezoelectric crystal based pressure sensor has been adapted to measure the pressure time history. As the pressures rise on short time scales (∼few μs to ms) it results in impulse-like loading. Foil, vessel and various electrical parameters can be changed to regulate the pulse characteristics. Varying pulse characteristics are seen to excite different vibration modes in the vessel. Full field dynamic strain measurements have been carried out using non-contact optical techniques like Digital Image Correlation. Empirical scaling of the performance of the pressure vessels with varying dynamic load along with numerical analysis will be presented in this paper. (author)