Plasma stopping-power measurements reveal transition from non-degenerate to degenerate plasmas

• Published in: Nature physics Vol. 16; no. 4; pp. 432 - 437
• Main Authors: Hayes, A. C., Gooden, M. E., Henry, E., Jungman, Gerard, Wilhelmy, J. B., Rundberg, R. S., Yeamans, C., Kyrala, G., Cerjan, C., Danielson, D. L., Daligault, Jérôme, Wilburn, C., Volegov, P., Wilde, C., Batha, S., Bredeweg, T., Kline, J. L., Grim, G. P., Hartouni, E. P., Shaughnessy, D., Velsko, C., Cassata, W. S., Moody, K., Berzak Hopkins, L. F., Hinkel, D., Döppner, T., Le Pape, S., Graziani, F., Callahan, D. A., Hurricane, O. A., Schneider, D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-04-2020; Nature Publishing Group; Nature Publishing Group (NPG)
• Subjects: 639/766/1960/1135; 639/766/34/4118; 639/766/483/1139; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Astronomical models; Atomic; Brown dwarf stars; Charged particles; Classical and Continuum Physics; Compact astrophysical objects; Complex Systems; Condensed Matter Physics; De Broglie wavelengths; Electron density; Electron gas; Energy dissipation; Energy loss; Fuels; Ignition; Implosions; Laser-produced plasmas; Mathematical and Computational Physics; Molecular; Nuclear fuels; Nuclear reactions; Optical and Plasma Physics; Physics; Physics and Astronomy; Plasmas (physics); Power measurement; Quantum mechanics; Stopping power; Theoretical; Transport properties
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/s41567-020-0790-3

Physically realized electron gas systems usually reside in either the quantum non-degenerate or fully degenerate limit, where the average de Broglie wavelength of the thermal electrons becomes comparable with the interparticle distance between electrons. A few systems, such as young brown dwarfs and the cold dense fuels created in imploded cryogenic capsules at the National Ignition Facility, lie between these two limits and are partially degenerate. The National Ignition Facility has the unique capability of varying the electron quantum degeneracy by adjusting the laser drive used to implode the capsules. This allows experimental studies of the effects of the degeneracy level on plasma transport properties. By measuring rare nuclear reactions in these cold dense fuels, we show that the electron stopping power, which is the rate of energy loss per unit distance travelled by a charged particle, changes with increasing electron density. We observe a quantum-induced shift in the peak of the stopping power using diagnostics that measure above and below this peak. The observed changes in the stopping power are shown to be unique to the transition region between non-degenerate and degenerate plasmas. Our results support the screening models applied to partially degenerate astrophysical systems such as young brown dwarfs.
Transitions between non-degenerate and degenerate plasma are observed in laser-driven implosions of cryogenic capsules at the National Ignition Facility. The observed partially degenerate regime is relevant to the physics of young brown dwarfs.