Laboratory measurements of resistivity in warm dense plasmas relevant to the microphysics of brown dwarfs

N. Booth, A. P. L. Robinson, P. Hakel, R. J. Clarke, R. J. Dance, D. Doria, L. A. Gizzi, G. Gregori, P. Koester, L. Labate, T. Levato, B. Li, M. Makita, R. C. Mancini, J. Pasley, P. P. Rajeev, D. Riley, E. Wagenaars, J. N. Waugh, N. C. Woolsey

Nature Communications 6, Article number: 8742 (2015)

Abstract

Since the observation of the first brown dwarf in 1995, numerous studies have led to a better understanding of the structures of these objects. Here we present a method for studying material resistivity in warm dense plasmas in the laboratory, which we relate to the microphysics of brown dwarfs through viscosity and electron collisions. Here we use X-ray polarimetry to determine the resistivity of a sulphur-doped plastic target heated to Brown Dwarf conditions by an ultra-intense laser. The resistivity is determined by matching the plasma physics model to the atomic physics calculations of the measured large, positive, polarization. The inferred resistivity is larger than predicted using standard resistivity models, suggesting that these commonly used models will not adequately describe the resistivity of warm dense plasma related to the viscosity of brown dwarfs.