Warm Dense Copper conductivity measurements using single-shot THz spectroscopy*

Understanding WDM is critical for optimizing Inertial Confinement Fusion trajectory and modeling planetary dynamos. However, predicting WDM properties remains difficult due to the combination of non-trivial degeneracy and strong Coulomb coupling. While state-of-the-art computational tools are in development for predicting the transport properties of materials at WDM conditions, experimental data needed to validate such models are scarce [1].

 

Here we present near-zero-frequency (DC) electrical conductivity measurements of warm dense copper determined by THz spectroscopy [2,4]. Copper thin films were heated using intense laser pulses to WDM conditions and probed using single-cycle THz pulses. Combining the measured conductivities with temperature estimates based on the Two-Temperature model [5], the results of these measurements are compared with theoretical predictions and previous experimental measurements [6-9]. This represents an important step towards benchmark quality measurements, which are essential to provide critical tests of computational methods.

References:

[2] McKelvey, A., et al. 2017, Scientific Reports, 7(1), 7015

[3] B. K. Ofori-Okai, Rev. Sci. Instrum. 89(10), 10D109 (2019)

[4] B. K. Ofori-Okai, Phys. Plasmas 31(4), 042711 (2024)

[5] M. Maigler, Proc. SPIE 12939, High-Power Laser Ablation VIII, 129390Q (2024)

[6] S. Park, et al. Appl. Phys. Lett. 119(17), 174102 (2021)

[7] R. A. Matula, et al. J. Phys. Chem. Ref. Data 8, 1147 (1979)

[8] R. A. Grosse, Inorg. Nucl. Chem. Lett. 5, 963 (1969).

[9] A. W. DeSilva and J. D. Katsouros, Phys. Rev. E 57(5), 5945 (1998).