Equation of State Measurements for Proton Heated Warm Dense Matter on the OMEGA-EP

Understanding the behavior of materials in the warm dense matter regime can significantly extend the knowledge in fields ranging from astrophysics to high energy density physics. Of particular importance is understanding the equation of state (EOS), which describes the relationship between pressure, volume, temperature, and the internal energy of a system at a state of thermodynamic equilibrium. We demonstrate the measurement of release isentrope of warm dense aluminum heated isochorically by a proton beam generated by the OMEGA EP short-pulse laser. We have used specially designed targets to guide the protons so that we can reach different initial temperatures. Three EP long-pulse beams were used to heat an X-ray backlighter to provide an X-ray source for streaked X-ray radiography. Various backlighter energies were used to cover a wide range of densities. Following a method derived by Foord et al. [1], we can analyze the results accurately enough to obtain a pressure-density isentrope curve for benchmarking various EOS models.



[1] M. E. Foord et al., RSI 78, 2586 (2004).