Transient and Turbulent Fields in Plasmas

目前正在进行关于磁化等离子体中电流和热脉冲传输的瞬态效应的实验研究，以及关于波动磁场中相干结构的湍流研究。 这些过程解决了基本的等离子体性质，这是必不可少的了解等离子体中的传输，它们是广泛的兴趣，惯性和磁聚变，脉冲功率，并在空间等离子体的主动实验。 拟议的工作将在具有出色诊断能力的大型受控实验室等离子体中进行。 脉冲电流由电极、粒子束和磁天线施加。 这些电流的电磁波，如动力阿尔芬波，哨声和光束模式的运输将进行研究。 热脉冲是由磁天线的脉冲、强射频场产生的。 近无碰撞等离子体中的热输运不能用经典的扩散模型来描述，而可能涉及双层和非麦克斯韦分布。 使用定向速度分析仪，发射电场探头和矢量磁场探头可在3维空间移动，将产生场和粒子的详细图像。 磁湍流将从热水平到环境场水平进行研究。 它是由粒子束中的电流波动激发的，在回旋谐波频率下形成相干射频结构，或者是由不稳定性激发的，比如在高β等离子体中产生束的哨声和低混杂湍流。 利用条件平均法，一种采用数字示波器的特殊统计技术，可以分辨湍流场中的相干磁结构。 将绘制这些“岛屿”中的场和粒子图，以便在微观尺度上研究输运过程。 将开发完善的等离子体诊断工具和技术。 这些详细的实验将有助于加深人们对等离子体基本性质的认识，对等离子体的各种用途有一定的影响，并有助于培养学生现代实验等离子体物理的能力。

Experimental research is being pursued on transient effects dealing with the transport of current and heat pulses in magnetized plasmas and turbulence studies dealing with coherent structures in fluctuating magnetic fields. These processes address fundamental plasma properties which are essential for understanding transport in plasmas, and they are of broad interest in inertial and magnetic fusion, pulsed power, and for active experiments in space plasmas. The proposed work will be performed in a large, controlled laboratory plasma with excellent diagnostic capabilities. Pulsed currents are imposed with electrodes, particle beams and induced by magnetic antennas. The transport of these currents by electromagnetic waves such as kinetic Alfven waves, whistlers and beam modes will be studied. Heat pulses are generated with pulsed, intense rf fields of magnetic antennas. The heat transport in nearly collisionless plasmas cannot be described by classical diffusion models but may involve double layers and non- Maxwellian distributions. Using directional velocity analyzers, emissive electric field probes and vector magnetic field probes moveable in 3 dimensions will yield a detailed picture of fields and particles. Magnetic turbulence will be investigated from the thermal level to that of the ambient field. It is excited by current fluctuations in particle beams forming coherent rf structures at cyclotron harmonic frequencies or by instabilities such as beam-generating whistlers and lower hybrid turbulence in high-beta plasmas. Using conditional averaging, a special statistical technique employing digital oscilloscopes, coherent magnetic structure can be resolved in a turbulent field. Fields and particles in such "islands" will be mapped so as to study transport processes on a microscopic scale. Refined plasma diagnostic tools and techniques will be developed. Such detailed experiments are expected to advance the knowledge of basic plasma properties, have i mplications to the various uses of plasmas, and train students in modern experimental plasma physics.