中文摘要：

利用等离子体光学波段自发光成像、光学光谱和光学探针干涉等诊断手段，观察了纳秒脉冲激光烧蚀固体靶产生的等离子体在外加横向磁场中的膨胀过程．根据实验参数特征建立了简化的磁流体物理模型，结合自发光强度的时间演化，理论计算了等离子体温度和密度参数的时间演化，理论计算结果与实验测量结果基本符合，证实了碰撞磁扩散过程在等离子体演化中发挥了关键作用．

英文摘要：

The nanosecond laser produced plasma expansion in an external transverse magnetic field is explored by using optical imaging of plasma self-luminescence, optical spectrum and optical interferometry techniques. The plasma displays bifurcation and focusing phenomena in a transverse magnetic field, which is different from the scenarios without external magnetic field significantly. We set up a simplified magnetohydrodynamics model according to the feature of experimental parameters. The theoretical results of the temporal evolutions of the plasma density and the temperature are in good agreement with the experimental results, which confirms the important role of the magnetic diffusion in the plasma evolution.