Measurement of the Adiabatic Index in Be Compressed by Counterpropagating Shocks

C. Fortmann, H. J. Lee, T. Döppner, R. W. Falcone, A. L. Kritcher, O. L. Landen, S. H. Glenzer
2012 Physical Review Letters  
We report on the first direct measurement of the adiabatic index γ through X-ray Thomson Scattering from shock-compressed beryllium. 9 keV x-ray photons probe the bulk properties of matter during the collision of two counter-propagating shocks. This novel experimental technique determines γ using only the measured mass densities and vanishing particle velocity at the point of shock collision to close the Rankine-Hugoniot equations. We find γ > 5/3 at 3x compression, clearly different from ideal
more » ... gas behavior. At 6x compression, γ shows the convergence to the ideal gas limit, in agreement with linear scaling laws.
doi:10.1103/physrevlett.108.175006 pmid:22680877 fatcat:g6kp5y2xu5bfdkx6f4n7el4mf4