采用构形磁流体力学计算程序SSS/MHD对炸药爆轰驱动固体套筒压缩磁场实验进行了一维磁流体力学模拟计算,得到空腔磁场以及样品管内壁速度随时间的变化历程,分别与磁探针和激光干涉测量的实验结果符合.由分幅照相结果阐述了套筒压缩空腔磁场过程中的屈曲失稳和Bell-Plesset不稳定性现象.分析了样品管和套筒中的磁扩散、涡流和磁压力的变化规律.结果表明,由于聚心运动下样品管和套筒的运动速度不同、电磁力和内爆作用力平衡等原因,样品管内靠近磁腔处的磁场、涡流和磁压力均高于套筒内距磁腔相同位置处的结果.讨论了样品管内距磁腔0.05mE处的熵增随该点压缩度的变化,最大熵增与样品管材料定容比热的比值在10%左右,爆炸磁压缩实验过程的等熵程度较高.
Magnetic cumulative generator (MC-1) is a kind of high energy density dynamic device. A liner is driven by a cylindrical explosive implosion to compress the magnetic flux preset in the cavity. Then the chemical energy is converted into magnetic one, which is cumulated nearby the axis to form ultra-intense magnetic field used to load sample in non-touch manner. This loading technique can bring higher pressure and relatively low elevated temperature in the sample and has a very high-degree isentropy in the course of compression. The configuration magneto-hydrodynamic code SSS/MHD is used to develop one-dimensionM magneto-hydrodynamic calculation of magnetic flux compression with explosion driven solid liner. The calculation results of magnetic field in cavity and velocity of inner wall of sample tube are obtained and accord with the magnetic field measured by probe and the velocity measured by laser interference. The buckling and Bell-Plesset instabilization produced by linearly compressing magnetic field are shown through frame photography. The change laws of magnetic diffusion, eddy current and magnetic pressure in liner and sample tube are analyzed, which show that the magnetic field and pressure and eddy near to cavity in the sample tube are all higher than the ones in the liner with the same distance to cavity. The balance between the electromagnetism force and implosion action and the difference between sample tube and liner velocities are the main reasons under imploding movement. The change of isentropic increment with compression degree at the same location, whose distance is 0.05 mm to magnetic cavity in the sample tube, is discussed. The result indicates that the ratio of the maximum increment to specific heat of sample tube material is about 10%, which shows that the process of compression magnetic flux with explosion is quasi-isentropic. In general, SSS/MHD code can reveal in depth the physic images which are difficult to measure or observe in the magneto-hydrodynamics experiment.