“聚龙一号”装置上磁驱动铝飞片实验的数值模拟

采用二维磁驱动数值模拟程序MDSC2,对大电流脉冲装置"聚龙一号"上的151发次磁驱动370μm厚铝飞片实验、164发次磁驱动330μm厚铝飞片实验进行了数值模拟和分析。数值模拟表明:370μm厚铝飞片和330μm厚铝飞片的磁驱动过程中,VISAR测量的速度不是飞片自由面的速度,而是飞片中邻近自由面最近的固体反射面的速度。这是由于磁驱动飞片发射过程中,飞片自由面部分被烧蚀,密度低于固体密度状态,而飞片自由面和加载面中间的飞片还保持固体密度状态。VISAR测量的激光将穿过自由面的低于固体密度状态的飞片部分,到达飞片自由面最近的固体密度位置再反射回去,获得这一位置的飞片速度。数值模拟的飞片固体反射面速度历史和VISAR测量的速度历史相吻合。

Numerical simulation of magnetically driven aluminum flyer plate on PTS accelerator

Magnetically driven flyer plate experiments, shot 151 with a 370 m thick aluminum flyer plate and shot 164 with a 330 m thick aluminum flyer plate, carried out in the large current pulse device PTS are simulated and analyzed with the two-dimensional magneto-hydrodynamics code MDSC2. Numerical simulation shows that the material near the free surface of the flyer plate melts or evaporates due to ablation, with the remaining part between the free surface and the loading surface staying solid. This finding tells us that the velocity measured by VISAR in the experiments may not be that of the free surface as expectation but be the one of the liquid-solid interface beyond the free surface, since the laser of the VISAR will penetrate through the melt or evaporated part and reflect back at the liquid-solid interface. This idea is confirmed by the coincidence of the simulated velocity of the liquid-solid interface and the measured one by the VISAR.