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Title: Opacity and conductivity measurements in noble gases at conditions of planetary and stellar interiors

The noble gases are elements of broad importance across science and technology, and are primary constituents of planetary and stellar atmospheres, where they segregate into droplets or layers that affect the thermal, chemical, and structural evolution of their host body. We have measured the optical properties of noble gases at relevant high pressures and temperatures in the laser-heated diamond anvil cell, observing insulator-to-conductor transformations in dense helium, neon, argon, and xenon at 4,000 to 15,000 K and pressures of 15-52 GPa. The thermal activation and frequency-dependence of conduction reveal an optical character dominated by electrons of low mobility, as in an amorphous semiconductor or poor metal, rather than free electrons as is often assumed for such wide band gap insulators at high temperatures. White dwarf stars having helium outer atmospheres cool slower and may have different color than if atmospheric opacity were controlled by free-electrons. As a result, helium rain in Jupiter and Saturn becomes conducting at conditions well correlated with increased solubility in metallic hydrogen, while a deep layer of insulating neon may inhibit core erosion in Saturn.
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Carnegie Inst. of Washington, Argonne, IL (United States); Univ. of Edinburgh, Edinburgh (United Kingdom); Univ. de Los Andes, Bogota DC (Columbia); Howard Univ., Washington, D.C. (United States)
  2. Carnegie Inst. of Washington, Argonne, IL (United States)
  3. Deutsches Elektronen-Synchrotron Photon Science, Hamburg (Germany)
  4. Carnegie Inst. of Washington, Argonne, IL (United States); Howard Univ., Washington, D.C. (United States)
  5. Carnegie Inst. of Washington, Argonne, IL (United States); Chinese Academy of Sciences, Hefei (China)
Publication Date:
Grant/Contract Number:
NA0002006; FC52-08NA28554; EFREE; Instrumentation grant
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 26; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Carnegie Institution of Washington, Washington, D.C. (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; rare gases; extreme conditions; warm dense matter; giant planet; white dwarf
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1335154