CURRENT SCIENCE, VOL. 82, NO. 2, 25 JANUARY 2002, Equation-of-state studies using laser-driven shock wave propagation through layered foil targets
H. C. Pantâ€ ,*, M. Shuklaâ€ , V. K. Senechaâ€ , S. Bandyopadhyayâ€ , V.N. Raiâ€ , P. Khareâ€ , R. K. Bhatâ€ , B. K. Godwal# and N. K. Gupta#
â€ Laser Plasma Division, Centre for Advanced Technology, Indore 452 013, India
#High Pressure Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085,
India Results of laser-driven shock wave experiments for equation-of-state (EOS) studies of gold metal are presented. A Nd : YAG laser chain (2 Joule, 1.06 mm wavelength, 200 ps pulse FWHM) is used for generating shocks in the planar Al foils and Al + Au layered targets. EOS of gold in the pressure range of 9â€“13 Mbar is obtained using impedance-matching technique. Numerical simulations performed using onedimensional radiation hydrodynamic code supports the experimental results. Experimental data show remarkable agreement with results from studies using the existing standard EOS models and with other experimental data obtained independently using laser-driven shock experiments.
STUDY of matter under extreme pressure conditions is a subject of great interest in several branches of physics, in particular, astrophysics, materials science and inertial confinement fusion research1â€“3. A proper knowledge of the equation-of-state (EOS) of materials at high pressures is the key requirement for such studies. EOS data4,5 are also an important input to hydrodynamic codes used for the simulations of fission, fusion devices and their effects. Extensive data on materials have been generated using static and dynamic shock-wave techniques6. The range of such data using diamond-anvil cell and two-stage gas gun are limited to 5 and 10 Mbar pressures, respectively5. Theoretical treatment of materials in such compressed states is carried out using solid and liquid state theories7. The current state-of-the-art condensed matter models based on density functional theories, employing generalized gradient approximation for exchange and correlation potentials, have demonstrated their capabilities to predict phase transitions that, in turn, have been confirmed by experiments7. Remarkable agreement between theory and the state-of-the-art experiments has demonstrated beyond doubt that first-principle simulations can be carried out reliably to predict thermodynamic states of the materials up to 10 Mbars8.It is also well known that different variants of Thomasâ€“Fermiâ€“Dirac theory can be used to predict EOS ... ... ... . .... " .... read on
CURRENT SCIENCE, VOL. 85, NO. 6, 25 SEPTEMBER 2003, Equation-of-state study of copper using laser-induced shocks near 10 Mbar pressure and revalidation of theoretical modelling
M. Shuklaâ€ ,*, H. C. Pantâ€¡, V. K. SenechaÂ§, V. N. RaiÂ§, P. KhareÂ§Â§, A. K. Vermaâ€ , R. S. Raoâ€ , N. K. Guptaâ€ and B. K. Godwalâ€
â€ High Pressure Physics Division, Purnima Labs, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
â€¡Center for Advanced Technology, Indore 452 013, India
Â§Laser Plasma Division and Â§Â§Magnet Division, Center for Advanced Technology, Indore 452 013, [/url]
India Laser-driven shock wave experiments have been performed to determine equation of state (EOS) of copper using impedance matching technique in the pressure range 8â€“11 Mbar. A 2J/200 ps Nd : YAG laser beam is used to induce dynamic shocks in aluminium foil (reference material) and Alâ€“Cu layered targets. EOS of copper is obtained at shock pressures of 8.9 Mbar and 10.4 Mbar with a pressure enhancement of ~ 1.66 at Alâ€“Cu interface. The experimental data points are consistent with the predictions of the EOS model based on first principle theory and are also in close agreement with the simulation results obtained using one-dimensional radiation hydro-code MULTI that uses SESAME data tables for EOS and opacity values.
EQUATION-of-state (EOS) of a material at high pressures is an important input parameter for astrophysics, geophysics, inertial confinement fusion and hydrodynamic codes used for the simulation of fission, fusion devices. The EOS data up to 5 Mbar pressure is obtained with high explosive loading facility or using a high-pressure gas gun1. The pressure above 10 Mbar in the past had been obtained from underground nuclear explosions, but these measurements are difficult due to high cost and require large experimental configurations2â€“4. The efforts in the recent past reveal that laser-driven shock wave technique can be employed for achieving shock pressures of 10â€“40 Mbar within 15â€“20% accuracy in the laboratory conditions5,6. Recently, experiments using indirect drive method measures the shock pressure within an accuracy of 3â€“4% (ref. 7). With these developments it appears that laser-driven shocks can be used for the generation of accurate high-pressure data. These data can be utilized as a testing ground for the first principle theoretical models that is used for generating the EOS data in the pressure region not yet accessible experimentally. In this paper we present the extension of laser-driven shock wave experiments performed at CAT, Indore, to determine the EOS of copper (Cu) between 8 and 11 Mbar using impedance ... ... ... . .... .... read on