Plasma Waves and the Compressibility of Warm Dense Hydrogen*

Recent experiments on single- and double-shocked liquid deuterium[1,2] have provided new evidence for increased compressibility of hydrogen compared to theoretical models in the warm-dense-matter regime between 200 and 1000 GPa. We show that a specific heat contribution from plasma waves, not explicitly included in the theoretical models, is sufficient to explain the discrepancy. 

 

[1] A. Fernandez-Pañella et al., Phys. Rev. Lett. 122, 255702 (2019).

[2] D. E. Fratanduono et al., Phys. Plasmas 26, 012710 (2019).