The Fiber-Array Probe Technique For Perturbation Damping Measurement And The Viscosity Of Substances Under Shock Compression

Viscosity of substances under high temperature and high pressure states has been one of the important transport properties in condensed matter physics, geophysical dynamics and weapon physics. However, there is no well-accepted experimental technique to measure the viscosity coefficient of materials under the extreme condition, especially for non-metal materials. In1965, Sakharov et al firstly presented a new technique based on the small perturbation theory, and measured the viscosity of several metals such as Al, Fe, U, and Pb under shock conditions, by explosive loading technique. But only one experimental data point at31GPa has been reported so far, Miller and Ahrens made more strict treatment for the experiment results of Sakharov, and pointed out that an initial flow field must be introduced for well explaining the experimental result. In order to simplify the above experimental method and test the experimental results, In2005, Liu et al proposed a new experimental technique known as the electric pin technique, the planar flyer directly impacted sinusoidally grooved surface of sample under the light gas gun loading conditions. The shear viscosity coefficient of shock-compressed Al and Fe was directly determined, and some valuable results were obtained. But it is difficult for the electrical pin to avoid the electromagnetic interference, and it is difficult to meet the requirements for the measurement of non-metallic materials. Therefore, a new experimental technique is needed to measure the viscosity of non-metallic materials under high pressure and high temperatures.The some progresses in the experimental technique have been made in this thesis to measure the shear viscosity coefficient of non-metallic materials under high pressure, which is much different from previous work. The main conclusions are as follows:K A new fiber-array probe technique based on the flyer-impact small-disturbance experiment method was established and improved, the technique not only avoid the electromagnetic interference and simplify experimental operation, but also can measure the characteristics of the shock-wave disturbance damping in non-metallic material.2> To easily compare with the results given by electrical pin technique, the newly developed method is applied to investigate the effective viscosity of aluminum at71GPa, although the experimental results show little away from the measurement results, both in the same order of magnitude. It proved that the technique requirements have been met.3、 The shear viscosity coefficient of olivine is firstly measured by the technique and determined to be5000Pa·s at40GPa. A new experimental technique is provided to the study of viscosity coefficient for non-metallic materials under high pressure.