Laboratory Studies of Alfven Waves

9310084山田将加强现有的实验室设施，以创建一个主要的磁重联实验(MRX)设施。磁重联是磁层物理、太阳物理和天体物理等离子体中的一个关键物理过程。磁力线构型的拓扑变化通常会导致大的JxB力，将磁能释放到MHD流中，并创建拓扑上不同的等离子体构型。MRX将被用来研究微尺度重联区的基本拓扑以及全球MHD流动和平衡。等离子体标度与空间等离子体条件密切相关，其大的Lundquist数(或磁雷诺数)约为2000，系统中的许多回转半径(约100)。在不同的初始状态下，我们将使用一种灵活的双球组态来测量(1)重联过程是否保持轴对称或三维现象是否会自发爆发，(2)重联率如何取决于Mergin球面的螺旋度，(3)重联率与整体磁流体力的依赖关系，这种力可以通过MRX线圈和磁芯中的电流来控制，(4)与重联和热转换相关的流场，以及(5)片状重联的演变，其中等离子体会聚到一点而不是沿一条线。诊断将包括磁性和朗缪尔探头阵列、成像干涉仪，以及通过对蒸发的杂质颗粒进行高速摄影进行的流动可视化。在东京大学的TS-3装置上，已经进行了双球面的初步实验。***

9310084 Yamada Existing laboratory facilities will be enhanced to create a major facility for magnetic reconnection experiments (MRX). Magnetic reconnection is a key physical process in magnetospheric physics, solar physics, and astrophysical plasmas generally. Topological changes in magnetic field line configuration often result in large JxB forces with release of magnetic energy into MHD flows and the creation of topologically distinct plasmoid configurations. The MRX will be used to investigate the fundamental topology of microscale reconnection regions as well as the global MHD flows and equilibria. Plasma scaling is established to be very relevant to space plasma conditions with a large Lundquist number (or magnetic Reynolds number) of about 2000 and many gyroradii in the system (about 100). A flexible double spheromak configuration will be used under various initial states to measure (1) whether reconnection processes remain axisymmetric or whether three-dimensional phenomena will spontaneously break out, (2) how the reconnection rate depends on the helicity of mergin spheromaks, (3) the dependence of reconnection rate on global MHD forces which can be controlled via currents in the MRX coils and cores, (4) flow fields associated with reconnection and the transformation to heat, and (5) the evolution of patchy reconnection where plasmas converge to a point instead of along a line. Diagnostics will include magnetic and Langmuir probe arrays, an imaging interferometer, and flow visualization via high-speed photography of vaporized impurity pellots. Preliminary experiments on double spheromaks have already been carried out on the TS-3 device at the University of Tokyo. ***