Reaching Isochoric States of Matter by Ultrashort-Pulse Proton Heating

Abstract

The aim of this LDRD is to develop two completely new methods for creating and probing warm dense states of matter (plasmas at several eV at solid density), which will enable the direct measurement of fundamental material properties such as the opacity and equation of state (EOS). There is in this warm dense regime an almost complete lack of quantitative experimental data-primarily because of the difficulty in creating uniform, single temperature/density plasmas on which to make measurements. In an ideal case one would volumetrically heat a target with a very short burst of energy-simultaneously making measurements prior to the subsequent hydrodynamic expansion of the target. However, no mechanism for such rapid, uniform heating of a material currently exists. We propose to develop a completely new technique that has the potential for creating large uniform plasmas in local thermodynamic equilibrium (LTE) at warm dense conditions. This technique is based on volumetric heating of solid density targets with a high energy, high-flux, short-pulse, laser-produced proton beam. We also propose to use this beam of protons to probe high-Z, solid density matter with both 2-dimensional spatial resolution and picosecond temporal resolution. The combination of these two techniques will enable us to make the very first quantitative measurements of the equation of state and opacity of an isochorically heated state of matter.