Abstract
The accurate hydrodynamic description of an event or system that addresses the equations of state, phase transitions, dissociations, ionizations, and compressions, determines how materials respond to a wide range of physical environments. To understand dense matter behavior in extreme conditions requires the continual development of diagnostic methods for accurate measurements of the physical parameters. Here, we present a comprehensive diagnostic technique that comprises optical pyrometry, velocity interferometry, and time-resolved spectroscopy. This technique was applied to shock compression experiments of dense gaseous deuterium–helium mixtures driven via a two-stage light gas gun. The advantage of this approach lies in providing measurements of multiple physical parameters in a single experiment, such as light radiation histories, particle velocity profiles, and time-resolved spectra, which enables simultaneous measurements of shock velocity, particle velocity, pressure, density, and temperature and expands understanding of dense high pressure shock situations. The combination of multiple diagnostics also allows different experimental observables to be measured and cross-checked. Additionally, it implements an accurate measurement of the principal Hugoniots of deuterium−helium mixtures, which provides a benchmark for the impedance matching measurement technique.
Highlights
The unique behaviors of deuterium and helium under high pressures and temperatures are always of great scientific interest related to several significant problems in modern physics
Falk et al performed equation of state (EOS) experiments for deuterium using the Omega laser.[12,15]. They obtained the shock pressure and density of liquid deuterium with the help of theoretical models through comparisons with experimental observables of shock velocity measured by a velocity interferometer system for any reflector (VISAR) and temperature measured by an independent streaked-opticalpyrometry (SOP) system
The signal of multi-channel optical pyrometers (MCOPs) shows a small slope with time during the first shock transit, which can be clearly seen from 430 nm channel
Summary
The unique behaviors of deuterium and helium under high pressures and temperatures are always of great scientific interest related to several significant problems in modern physics. Most experiments use the impedance matching (IM) method to determine the pressure and density of the shocked deuterium or helium. This technique requires a shock pusher with well-known EOS that transfers the shock into the sample and is used to determine the Hugoniot. Falk et al performed EOS experiments for deuterium using the Omega laser.[12,15] they obtained the shock pressure and density of liquid deuterium with the help of theoretical models through comparisons with experimental observables of shock velocity measured by a velocity interferometer system for any reflector (VISAR) and temperature measured by an independent streaked-opticalpyrometry (SOP) system. We describe this technique and explain the above three aspects (1), (2), and (3) in detail
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