超高速碰撞产生瞬态磁场的时间尺度特征

在超高速碰撞的早期阶段会产生瞬态等离子体云,等离子体云能以某种机理产生电流和磁场。在靶板表面的等离子体云中产生的非线性电子温度和电子密度梯度将产生磁场,场的持续时间从10-6s到约60s,依赖于弹丸的碰撞能量。本文利用超高速碰撞产生等离子体诱生磁场的一维理论模型,理论推导了喷出物诱生磁场的峰值,得到了碰撞喷出物膨胀过程中磁场增强、磁场衰减的时间尺度特征及磁感应强度峰值。结合超高速正碰撞实验,给出了碰撞喷出物膨胀等离子体云中瞬态磁场的时间尺度,并与理论时间尺度进行了比较,结果基本一致。

Time Evolution of Transient Magnetic Field in Plasma Cloud Induced by Hypervelocity Impact

Here,we addressed the time evolution of both the transient electrical current and magnetic field in the expansion plasma clouds,induced by hypervelocity impact at the initial stage of ion sputtering.The magnetic fields possibly originated from the non-linear temperature and electron density gradients on and above the layered target under heavy bombardment of projectile.The peaking and decaying of the magnetic field intensity,in a rapid increase-decrease pattern,ranging from 10-6 s to 60 s and depending on the impinging energy between projectile and target interaction,were analytically evaluated,based on the one-dimensional model of plasma generation by hypervelocity impact.The time-dependent variations in the magnetic fields were measured in the vertical impact experiment.The calculated results were found to agree fairly well with those of the experiments.