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Stability of shock waves in high temperature plasmas

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Title Stability of shock waves in high temperature plasmas
 
Creator DAS, M
BHATTACHARYA, C
MENON, SVG
 
Subject SPONTANEOUS ACOUSTIC-EMISSION
IONIZING MONATOMIC GASES
HYDROGEN IMPURITIES
IONIZATION
 
Description The Dyakov-Kontorovich criteria for spontaneous emission of acoustic waves behind shock fronts are investigated for high temperature aluminum and beryllium plasmas. To this end, the Dyakov and critical stability parameters are calculated from Rankine-Hugoniot curves using a more realistic equation of state (EOS). The cold and ionic contributions to the EOS are obtained via scaled binding energy and mean field theory, respectively. A screened hydrogenic model, including l-splitting, is used to calculate the bound electron contribution to the electronic EOS. The free electron EOS is obtained from Fermi-Dirac statistics. Predictions of the model for ionization curves and shock Hugoniot are found to be in excellent agreement with available experimental and theoretical data. It is observed that the electronic EOS has significant effect on the stability of the planar shock front. While the shock is stable for low temperatures and pressures, instability sets in as temperature rises. The basic reason is ionization of electronic shells and consequent increase in electronic specific heat. The temperatures and densities of the unstable region correspond to those where electronic shells get ionized. With the correct modeling of bound electrons, we find that shock instability for Al occurs at a compression ratio similar to 5.4, contrary to the value similar to 3 reported in the literature. Free electrons generated in the ionization process carry energy from the shock front, thereby giving rise to spontaneously emitted waves, which decay the shock front. (C) 2011 American Institute of Physics. [doi:10.1063/1.3653253]
 
Publisher AMER INST PHYSICS
 
Date 2012-06-26T09:51:25Z
2012-06-26T09:51:25Z
2011
 
Type Article
 
Identifier JOURNAL OF APPLIED PHYSICS,110(8)-
0021-8979
http://dx.doi.org/10.1063/1.3653253
http://dspace.library.iitb.ac.in/jspui/handle/100/14333
 
Language English