Laboratory Studies of Alfven Waves

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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. ***