Shock Compressed Xenon Equation Of State And Transient Spectra

Equation-of-state (EOS) and spectral data are important input parameter of computer simulations in radiant hydrodynamics. Therefore, it has the clear applied background and scientific significance in researching the thermodynamic character of dense xenon plasma with high temperature produced by shock compression technique.With the development of shock compression technique, the ionization and dissociation of the atoms and molecules become controllable. As far as know, the xenon's energy gap is smaller, so nonmetal-to-metal transition (NM-M-T) can be implemented through shock compression. Consequently, we could deeply realize the structural variety of the atoms and molecules as well as the interaction of particles, via studying the xenon plasma process and state, which is the developing trend of high-pressure condensed state physics extending to extreme condition and microscopic level.The main contents of this paper are experimental research, with theoretical analysis additively. According to investigating the EOS and spectral characteristic of xenon plasma produced by shock compressing dense gas from different initial states, we obtain some understandings for the shocked xenon plasma. The major results conclude as follows:The spectral radiation histories and transient spectrum of dense gaseous xenon under shock compression were measured by means of the multi-wavelength channel pyrometer (PMT) and the Optical Multi-channel Analyzer (OMA). The three experimental results from initial pressure 0.8MPa and one from initial pressure 4.72MPa with room temperature were presented by a two-stage light-gas gun. Shock velocity was measured and shock pressure was determined by the impedance matching method. The emissive and absorption spectra were acquired basing on the transient spectrum, which could deduce the plasma temperature and ionization. Also, the Hugoniot data of gaseous xenon under shock compression were obtained in the pressure range 2.3～15.8 GPa, and temperature of 30～50 kK.The radiating spectrum of xenon plasma were measured in the wavelength range from 460 to 680nm, which were linear spectra and syntonic absorption spectra of separate atoms or ions piled in sequential spectrum. The strong absorption in 589.33 and 670.48nm were observed in our experimental condition. With the temperature and density elevated, the number of absorption spectral line increased from which the increase ionization degree can be inferred. Meanwhile, assuming the Planck gray-body theory, the temperature of plasma was fitted from bundle curve of transient radiant spectrum, that could provide information used to connect the macroscopic and microscopic level, as well as set up the basis for analyzing the shock temperature.The theoretical computational method of EOS for dense xenon plasma in the range of experimental pressures and temperatures was established in terms of the Saha equation with the Debye-Huckel correction. According to chemical reaction process for xenon multi-ionization as a result of temperature effect, the EOS of xenon was estimated in broader pressure and temperature region. The experimental and computational results were compared with other experiments.