Abstract The particles transport and optical emission of tungsten plasma in magnetic field are two of the prime aspects for the diagnosis of plasma wall interaction process in nuclear devices such as EAST tokamak. In this work, the effect of the magnetic field (1.1 T) on the laser produced tungsten plasma plume dynamics and its optical emission produced by laser in vacuum (~4 × 10−3 Pa) were investigated. Fast imaging results presented that magnetic field confined the plasma and affected the plasma geometry. Temporal evolution of the optical emission showed that the continuum radiation at early stage (>100 ns) was not affected by the magnetic field while the tungsten ionic and atomic lines were significantly enhanced at later delay times (>200 ns, >400 ns, respectively). The negligible influence on the early continuum radiation was due to the laser-plasma pressure was far higher than the magnetic pressure as the plasma was hot and dense at early times. The higher electron temperature (Te) and electron density (ne) at later delay times were also observed in the magnetic field. The time-dependent plume dynamics in the magnetic field was correlated to the temporal variation of the plasma parameter β (the ratio of plasma pressure to magnetic pressure) and the electron collision frequency (ve), and electron cyclotron frequency (ωce) were also discussed. Moreover, the information including plasma evolution, plasma velocity, electron temperature electron density, ionic and atomic velocities with and without magnetic field were obtained.

中文翻译：

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横向磁场对真空中纳秒激光产生的钨等离子体羽流动力学和光发射的影响

摘要 钨等离子体在磁场中的粒子传输和光发射是诊断 EAST 托卡马克等核装置中等离子体壁相互作用过程的两个主要方面。在这项工作中，研究了磁场 (1.1 T) 对激光产生的钨等离子体羽流动力学及其在真空中 (~4 × 10−3 Pa) 激光产生的光发射的影响。快速成像结果表明，磁场限制了等离子体并影响了等离子体的几何形状。光发射的时间演化表明，早期（> 100 ns）的连续谱辐射不受磁场影响，而钨离子和原子线在后期（> 200 ns，> 400 ns）延迟时间显着增强）。对早期连续谱辐射的影响可以忽略不计，因为激光等离子体压力远高于磁压力，因为早期等离子体是热的和致密的。在磁场中也观察到在较晚的延迟时间较高的电子温度 (Te) 和电子密度 (ne)。磁场中随时间变化的羽流动力学与等离子体参数 β（等离子体压力与磁压力之比）和电子碰撞频率 (ve) 的时间变化相关，还讨论了电子回旋频率 (ωce) . 此外，还获得了等离子体演化、等离子体速度、电子温度、电子密度、有无磁场的离子和原子速度等信息。