高压物理学报

Electrical Conductivity Measurements for Metals under Shock Compression

BI Yan, TAN Hua, JING Fu-Qian, ZHAO Min-Guang

2003, 17(1): 1-7 . doi: 10.11858/gywlxb.2003.01.001

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Abstract:
A novel method using four electrodes perpendicular to shock front was proposed to measure the electrical conductivity of metals under shock compression up to megabar pressures. Using the drilled sapphire disk as insulator can eliminate the shunting effect, which will result in a higher conductivity data. The electrical conductivities of iron under shock compression in the final equilibrium pressures ranging from 101 to 208 GPa were obtained by using the two-stage light gas gun techniques. The measured conductivity of iron varies from 1.45106 S/m at 101 GPa and 2 010 K, to 7.65 105 S/m at 208 GPa and 5 220 K, which first extend the electrical conductivity measurements of iron to pressures beyond 200 GPa. The experimental results indicate that the Bloch-Grneisen equation describing the high-pressure electrical conductivity of metals still holds true up to 200 GPa for -Fe (hcp structure).

An in-Situ Raman Spectroscopy Study of Isochoric H2O-CO2-CH4 Fluids under High Temperature

CHEN Jin-Yang, ZHENG Hai-Fei, ZENG Yi-Shan, SUN Qiang

2003, 17(1): 8-15 . doi: 10.11858/gywlxb.2003.01.002

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Abstract:
The characteristics of the H2O-CO2-CH4 fluid at high temperature were studied by Raman spectroscopy. The results show that the Raman spectra of CH4 and CO2 do not influence each other, but they are both affected by H2O at high temperature. The hydrogen bonding of water decreases linearly before it becomes homogenous under isochoric condition. As the fluid becomes a homogenous gas, the Raman spectroscopy has little change with temperature. The hydrogen bonding of water, however, still remains in the homogenous liquid, even at the highest temperature of 520 ℃ in experiment. For the homogenous fluid at the highest temperature of 580 ℃ during measurement, the hydrogen bonding of liquid water remains relatively stronger.

Shock Temperatures of Porous Iron from MD Simulations

ZHANG Dai-Yu, LIU Fu-Sheng, LI Xi-Jun, JING Fu-Qian

2003, 17(1): 16-21 . doi: 10.11858/gywlxb.2003.01.003

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Abstract:
According to the assumption that porous iron sample has transformed to homogeneous medium under a given shock pressure, a Morse-type potential is used to simulate Hugoniot curve and shock temperatures of porous iron by MD method. The Morse potential has three adjustable parameters, which are determined from experimental data of iron's thermo-elastic properties by Matsui and Anderson. The simulation results are in good agreement with thermodynamic data for porous iron with a porosity of 12.1%, which implies that porous sample of a given porosity has a thermodynamic equilibrium temperature under a given shock pressure. However, whether the conclusion could be applicable to porous samples with larger porosities needs to be further verified by experiments.

Re-Initialized Level Set Method for Capturing 2D Compressible Multi-Fluid Interfaces

BAI Jing-Song, CHEN Sen-Hua

2003, 17(1): 22-28 . doi: 10.11858/gywlxb.2003.01.004

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Abstract:
We applied re-initialized level set method for enforcing level set function to preserve distancing character. Level set equation and fluid dynamic Euler equations were solved independently. Multi-fluid wave propagation method for fluid dynamic Euler equations and fifth order WENO scheme for re-initialization level set equation were used. Some comparable results for 2D compressible multi-fluid interface problems are given.

Mechanic Performances of Anti-Shoot Alumina Ceramic under Shock-Loading

DUAN Zhuo-Ping, GUAN Zhi-Yong, HUANG Feng-Lei

2003, 17(1): 29-34 . doi: 10.11858/gywlxb.2003.01.005

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Abstract:
In this paper, the Young's modulus and Poisson ratio of an alumina ceramic were determined by quasi-static experiments. The relationship between shock wave and particle velocity was obtained by measuring the shock wave and flying plate velocities with refer to 1-D plate impact tests. The longitudinal and lateral manganin gauges were used to determine the principal stresses in the shocked specimens, the lateral stress and longitudinal stress were measured in the 3～11 GPa range of shock stresses. Moreover, the shear strengths of the ceramic were determined from the difference between the longitudinal and lateral stresses.

Numerical Simulation of Thermodynamics Problem

LIN Hua-Ling, HUANG Feng-Lei

2003, 17(1): 35-44 . doi: 10.11858/gywlxb.2003.01.006

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Abstract:
The equations of hydrodynamics including conduction of heat are solved numerically by using the finite element method. The heat flow is calculated according to the Fourier's heat conduction. The temperature on the contact side of elements is calculated by the continuity condition of heat flow. According to triangular partitions divided from a quadrangle side of body element, convection heat flow is calculated. Considering the isotropic-elastic-plastic-hydrodynamic material model, the equation of state with three contributions, and the correlation between thermal conductivity and temperature, some computational examples, including the Fourier's heat conduction, contact heat transfer, deformation effects of heat, and shock compression of mixture, are given by the finite element code. The numerical simulation of shock temperature of mixture indicates that the temperatures among minute grains fluctuate, and tend to reach a thermal equilibrium during the shock propagation.

The Properties and Structural Investigation of ZnO Nanocrystals under Pressure

WU Zhen-Yu, CAO Li, BAO Zhong-Xing, LIU Cui-Xia, LI Qian-Shu, ZOU Bing-Suo

2003, 17(1): 45-49 . doi: 10.11858/gywlxb.2003.01.007

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Abstract:
The R-p relationship of ZnO nanocrystals and bulk materials were determined by diamond anvil cell (DAC). Research results show that a phase transformation begins at the 7.9 GPa when the particle is 20 nm nanocrystals, whereas the phase transition of ZnO bulk materials at 5 GPa. The smaller particle has larger phase transition pressure, and transformation pressure of bulk materials determined by DAC is lower than that previously reported. The structural properties of ZnO were discussed, and the domain fracture of nanocrystals under pressure was investigated.

New Method for Calculating Cold Energy, Cold Pressure and Cohesive Energy of Solids

RAN Xian-Wen, TANG Wen-Hui

2003, 17(1): 50-55 . doi: 10.11858/gywlxb.2003.01.008

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Abstract:
A new method for calculating cold energy, cold pressure and cohesive energy was poroposed. Cohesive energy calculations for 52 metals show that the calculated results using this method are consistent with the experimental data, especially for alkali metals. Comparison of Hugoniot curves calculated based on cold energy and cold pressure with the experimental Hugoniot data of aluminum, copper, zinc and silver, shows that this method can be applied to calculate cold energy and cold pressure of solid materials.

Experiment Designs and Uncertainty Assessments for Shock Temperature Measurements by Monte Carlo Method

LI Xin-Zhu, WANG Xiang

2003, 17(1): 56-64 . doi: 10.11858/gywlxb.2003.01.009

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Abstract:
In this paper, the Monte Carlo (MC) method was used to investigate the optimization of pyrometer design and the uncertainty assessment for shock-induced temperature measurements. The statistic T90%, which was defined by p{|T－Ttrue|T90%}=0.1, was calculated for 10 kinds of designs, and each case was simulated 2105 times to make the statistical sample. Four conclusions are presented: (1) Using more channels in a pyrometer can surely, but slightly improves the measurement accuracy of shock-induced temperature. (2) In the most case, measurement accuracy evidently depends on the accuracy of each channel. Generally, when the channel uncertainty is reduced from 10% to 5%, the experimental accuracy can be increased by over 150%. (3) The measurement accuracy also obviously depends on the channel's wavelength range. (4) The measurement accuracy can be largely improved by using those wavelength channels at which the difference of the radiation energy measured is as large as possible.

Study on Electronic Structure of ZnS: Mn2+

SHEN Han-Xin, SHEN Yao-Wen

2003, 17(1): 65-68 . doi: 10.11858/gywlxb.2003.01.010

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Abstract:
The electronic structures of Mn2+ luminescence centers in Mn-doped ZnS are studied by using first-principles linear muffin-tin-orbital method combining atomic sphere approximation. The calculated results for ZnS: Mn2+ show that the property of impurity energy level for single bug satisfies the theory of crystal potential field, and the influence of impurity energy level caused by concentration of impurity is not evident, which is consistents with the experiment results.

The Design and Experimental Examination of a Model EPW

CHU Zhe, ZHOU Gang, HAN Juan-Ni, YANG Qian-Long, WANG Ke-Hui, WANG Jin-Hai

2003, 17(1): 69-74 . doi: 10.11858/gywlxb.2003.01.011

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Abstract:
In this dissertation, a model EPW is designed on the basis of theoretical analyses. Shell material and parameters of a projectile body, such as slenderness ratio and CRH (caliber radius head), were studied. Strength check and aerodynamic properties of a projectile body were investigated. The experimental examination of a projectile on penetrating semi-infinite concrete medium was performed. The values from theoretical prediction have good coincidence with the experimental data. Young equation can be applied to estimate the penetration depth.

A System Utilizing Laser Diode for Gas-Gun Projectile Velocity Measurement

WANG Xiang, WANG Wei, FU Qiu-Wei

2003, 17(1): 75-80 . doi: 10.11858/gywlxb.2003.01.012

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Abstract:
A new system utilizing laser diode and PIN for gas-gun projectile velocity measurement were developed in 1997. The system is integrated in a barrel extension. It not only has the advantages of simple structure and vibration resistance but also has easiness of collimation. In addition, it is helpful to keep smaller tilt and to avoid projectile free-flying before it impacts the target. It has been used successfully to measure the velocity of irregular or nonmetallic projectile. The relative measurement uncertainty is less than 0.2%.

2003 Vol. 17, No. 1

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