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Mark B. Boslough Thomas J. Ahrens Arthur C. Mitchell 《Geophysical Journal International》1986,84(3):475-489
Summary. Temperatures of CaAl2 Si2 O8 (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. 相似文献
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W. J. Nellis 《Astrophysics and Space Science》2005,298(1-2):141-145
The shock compression curve (Hugoniot) of D2 has been controversial because the two data sets measured previously with a laser (L) and with pulsed currents (PC) differ
substantially. Recently, Hugoniot points of D2 have been measured at shock pressures of 123, 109, 61, 54, and 28 GPa using hemispherically converging, explosively-driven
systems (CS). The CS results are in good agreement with the PC data and the error bars of the CS-PC data are less than half
those of the L data. The limiting compression obtained from the best fit to the CS-PC data is 4.30 ± 0.10 at 100 GPa. The
CS-PC data are in good agreement with PIMC and DFT calculations, which is expected to be the case at higher shock temperatures
and pressures, as well. 相似文献
3.
Shock wave data for Jilin ordinary chondrite and Nandan iron meteorite are measured by electric-pin techniques on the dynamic
high-pressure device equipped with a two-stage light gas gun, and then equation-of-states supposedly fit for describing theirP- V-E relations are chosen to evaluate the values of their parameters. Demonstrated from the comparison between P-V curves of equation-of-states
and experimental data points, P-V relation of Jilin ordinary chondrite can be described by the universal equation-of-state,
of which bulk modulus value of zero-pressure Kos = 48.10 GPa, its pressure derivativeK’
os = 4.13. That of Nandan iron meteorite can be described by the three-term form of equation-of-state, of which the values of
two matter parameters Q = 41.235 31 GPa, q = 12. 27179. The Hugoniot data and equation-of-states for Jilin ordinary chondrite
and Nandan iron meteorite are first reported in this paper. The equation-of-state defined by Hugoniot data measurement provides
strong empirical support for describing the compression of meteorites to high pressure.
Project supported by the National Natural Science Foundation of China. 相似文献
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An intermediate shock-like event was observed by Voyager 2 on 9 January 1979. The discontinuity structure is well identified to be a 2→3 type intermediate shock by fitting the Rankine – Hugoniot
relations. The shock satisfies the following conditions: i) the plasma density increases from the upstream region to the downstream region, ii) The normal Alfvén Mach number (M
AN) is greater than unity in the preshock state and less than unity in the postshock state, iii) The fast-mode Mach numbers in the upstream and downstream regions are less than unity and both the slow-mode Mach numbers
are greater than unity, iv) The tangential component of the magnetic field changes sign across the shock front. 相似文献
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R. K. Anand 《地球物理与天体物理流体动力学》2017,111(5):394-409
The Rankine–Hugoniot (RH) jump relations for normal shock waves in van der Waals fluids have been studied in order to improve a theoretical understanding of those shock related phenomena as observed in a real atmosphere which cannot be accounted for by the ideal gas model. The RH jump relations for the pressure, density, particle velocity, temperature, speed of sound, adiabatic compressibility and change-in-entropy across the shock front have been analysed in terms of the non-idealness parameter of the gas, downstream Mach number and adiabatic index of the gas. Further, as the strength of shock waves may range from weak to strong, the convenient forms of RH jump relations for weak and strong shock waves have been discussed, simultaneously. Finally, the effects on the flow-field behind the shock front have been explored due to the non-idealness parameter of the gas, downstream Mach number and adiabatic index of the gas. 相似文献
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