Boslough, Mark B. and Ahrens, Thomas J. and Mitchell, Arthur C. (1986) Shock temperatures in anorthite glass. Geophysical Journal of the Royal Astronomical Society, 84 (3). pp. 475-489. ISSN 0016-8009. doi:10.1111/j.1365-246X.1986.tb04367.x. https://resolver.caltech.edu/CaltechAUTHORS:20141030-115645217
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Abstract
Temperatures of CaAl_2Si_2O_8 (anorthite glass) shocked to pressures between 48 and 117 GPa have been measured in the range from 2500 to 5600 K, using optical pyrometry techniques. The pressure dependence of the shock temperatures deviates significantly from predictions based on a single high-pressure phase. Either a variable specific heat, or the existence of three phase transitions, at pressures of about 55, 85 and 100 GPa and with transition energies of about 0.5 MJ kg^(−1) each (≈ 1.5 MJ kg^(−1) total) can explain the shock-temperature data. The proposed phase transition at 100 GPa can possibly be identified with the stishovite melting transition. Theoretical models of the time dependence of the thermal radiation from the shocked anorthite based on the geometry of the experiment and the absorptive properties of the shocked material yield good agreement with observations, indicating that it is not necessary to invoke intrinsic time dependences to explain the data in many cases. Observed time dependences were used to calculate absorption coefficients of the shocked material of from about 2 mm^(−1) to greater than 24 mm^(−1) — an increasing function of shock pressure. The assumption that the shocked material radiates as a black body is supported by the theoretical model, and by the close agreement between measured and calculated black body spectral radiance as a function of wavelength.
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| Additional Information: | Copyright © 1986 The Royal Astronomical Society. Accepted 1985 March 1. Received 1985 February 25; in original form 1984 March 4. We are indebted to E. Gelle, M. Long, and C. Manning of the Caltech Shock Wave Laboratory, and to D. Bakker, E. Jerbic and others at the Livermore facility for their expert technical help. We are grateful for the helpful discussions with G. Lyzenga, W. Nellis and J. Trainor. We wish to thank G. Rossman and his students at Caltech, who assisted in the determination of optical properties. Support was provided by NSF EAR78 12942 and NASA NGL-05-002-105 at the California Institute of Technology, and by the Lawrence Livermore National Laboratory. Contribution 3932, Division of Geological and Planetary Sciences, California Institute of Technology. | |||||||||
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| Subject Keywords: | anorthite; Hugoniot; optical pyrometry; phase transitions; shock temperature | |||||||||
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| Issue or Number: | 3 | |||||||||
| DOI: | 10.1111/j.1365-246X.1986.tb04367.x | |||||||||
| Record Number: | CaltechAUTHORS:20141030-115645217 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20141030-115645217 | |||||||||
| Official Citation: | Mark B. Boslough, Thomas J. Ahrens, and Arthur C. Mitchell Shock temperatures in anorthite glass Geophys. J. Int. (1986) 84 (3): 475-489 doi:10.1111/j.1365-246X.1986.tb04367.x | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 51067 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | George Porter | |||||||||
| Deposited On: | 30 Oct 2014 19:43 | |||||||||
| Last Modified: | 10 Nov 2021 19:05 |
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