Zhang Xuping, Wang Guiji, Zhao Jianheng, Tan Fuli, Luo Binqiang, Sun Chengwei
Institute of Fluid Physics, CAEP, Mianyang 621900, China.
Rev Sci Instrum. 2014 May;85(5):055110. doi: 10.1063/1.4875705.
High velocity flyer plates with good flatness and some thickness have being widely used to the field of shock physics for characterizations of materials under dynamical loading. The techniques of magnetically driven high-velocity flyer plates are further researched based on our pulsed power generators CQ-4 and some good results got on Sandia's Z machine. With large current of several mega-amperes, the loading surface of electrode panel will suffer acute phase transitions caused from magnetic diffusion and Joule heating, and the thickness and flatness of the flyer plates will change with time. In order to obtain the flyer plates with high performances for shock physics, some researches on electrode panels were done by means of LS-DYNA980 software with electro-magnetic package. Two typical configurations for high velocity flyer plates were compared from distribution uniformity of magnetic field in simulation. The results show that the configuration with counter-bore with "notch" and "ear" is better than the other. Then, with the better configuration panels, some experiments were designed and done to validate the simulation results and obtain high velocity flyer plates with good flatness for one-dimensional strain shock experiments on CQ-4. The velocity profiles of the flyer plates were measured by displacement interferometer systems for any reflectors. And the planarity of flyer plates was measured by using the optical fiber pins array for recording the flyer arrival time. The peak velocities of 8.7 km/s with initial dimension of 10 × 7.2 × 0.62 mm for aluminum flyer plates have been achieved. And the flyer plate with initial size of 12 × 9.2 × 0.73 mm was accelerated to velocity of 6.5 km/s with the flatness of less than 11 ns in the central region of 6 mm in diameter and the effective thickness of about 0.220 mm. Based on these work, the symmetrical impact experiments were performed to obtain the high accuracy Hugoniot data of OFHC (oxygen free high conductance) copper on CQ-4. The experimental results agree well with previous experiment's data given by Mcqueen and Marsh [J. Appl. Phys. 31, 1253 (1960)] and Mitchell and Nellis [J. Appl. Phys. 52, 3363 (1981)], and the experimental uncertainty of shock wave velocity is less than 2.4%.
具有良好平整度和一定厚度的高速飞片已在冲击物理学领域广泛应用，用于表征动态加载下的材料。基于我们的脉冲功率发生器CQ - 4，对磁驱动高速飞片技术进行了进一步研究，并在桑迪亚国家实验室的Z装置上取得了一些良好成果。在数兆安的大电流作用下，电极板的加载表面会因磁扩散和焦耳热而经历剧烈的相变，飞片的厚度和平整度会随时间变化。为了获得用于冲击物理学的高性能飞片，借助带有电磁包的LS - DYNA980软件对电极板进行了一些研究。从模拟中的磁场分布均匀性比较了两种典型的高速飞片构型。结果表明，带有“缺口”和“凸耳”的沉孔构型优于另一种。然后，使用较好构型的电极板设计并开展了一些实验，以验证模拟结果，并在CQ - 4上获得用于一维应变冲击实验的具有良好平整度的高速飞片。通过位移干涉仪系统测量任意反射器的飞片速度分布。使用光纤针阵列记录飞片到达时间来测量飞片的平整度。对于铝飞片，初始尺寸为10×7.2×0.62 mm时，已实现峰值速度8.7 km/s。对于初始尺寸为12×9.2×0.73 mm的飞片，在直径6 mm的中心区域平整度小于11 ns，有效厚度约为0.220 mm时，被加速到速度6.5 km/s。基于这些工作，在CQ - 4上进行了对称冲击实验，以获得无氧高导电率（OFHC）铜的高精度雨贡纽数据。实验结果与Mcqueen和Marsh [《应用物理杂志》31, 1253 (1960)]以及Mitchell和Nellis [《应用物理杂志》52, 3363 (1981)]给出的先前实验数据吻合良好，冲击波速度的实验不确定度小于2.4%。
