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Title: Modeling and Computation of Thermodynamic Properties of High Energy Density Systems
Authors: Ali, Amjad
Keywords: Physical Sciences
Issue Date: 2021
Publisher: Pakistan Institute of Engineering & Applied Sciences, Islamabad.
Abstract: High-energy-density system (HEDS), the matter having energy density that corresponds to pressures above about one million atmosphere are very important due to their wide occurrence in nature and are relevant to many fields like astrophysics and material sci ence etc. Knowledge of thermodynamic properties of HEDS are very important while designing and analyzing experiments using gas-dynamics simulations. Theoretically calculating these properties for a wide range of density and temperature is a compli cated task with many open questions to be addressed, and is the source of motivation for this research. This work presents calculations of these properties using average atom approach by improving Screened Hydrogenic Model with l-splitting. The continuum lowering part of the model is improved by adding level screened charge dependent energy along with exchange and correlations that correctly accounts for electron degeneracies. The ionic contributions to these properties are calculated using Cowan and scaled binding energy models whereas ion population fractions are calculated using classical theory of fluctuations. Thermodynamic properties are then calculated using standard thermody namic theory. A modular computer program named SHOPEOS is written in FORTRAN 95 that contains the original model and the improved models. SHOPEOS is capable of calculating electronic as well as ionic contributions of thermodynamics properties like electron level screened charges, level energies, average charge state, chemical potential, ion population fractions (IPF) and finally thermodynamics properties like pressure, en ergy, entropy, shock hugoniot profiles, specific heat at constant volume and pressure for a wide range of density and temperature under local thermodynamic equilibrium (LTE) conditions. By using SHOPEOS average charge state, IPF, thermodynamics properties, and shock hugoniot profiles are calculated for a wide range of density and temperature for beryllium, carbon, aluminum, iron, and gold plasmas. These results show an excellent xv agreement among different published theoretical models and experimental data. The maximum deviation of 0.5% is found in case of average charge state calculations as compared with published results whereas in case of IPF calculations a very good qual itative and quantitative behavior is found among different models. Finally, results of thermodynamic properties and shock hugoniot profiles showed an excellent agreement with published results.
Gov't Doc #: 23434
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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