Experimental Evaluation of Multi-spacecraft Data Analysis Techniques in a Laboratory Plasma

Yamada, Jongsoo Yoo and Masaaki

Princeton University. Plasma Physics Laboratory.

关键词: Data Analysis;    Vectors;    Magnetic Fields;    70 Plasma Physics And Fusion Technology;    Geometry;   

DOI  :  10.2172/1037450
RP-ID  :  PPPL-4749
RP-ID  :  DE-AC02-09CH11466
RP-ID  :  1037450

美国|英语

来源: UNT Digital Library

【 摘 要 】

The Magnetic Reconnection Experiment (MRX)[1] has been utilized to assess the effectiveness of minimum variance analysis on the magnetic field (MVAB) and boundary-crossing time analysis (BCTA). The neutral sheet is swept, or jogged, in a controlled manner with respect to the stationary probes by pulsed internal coil currents. Magnetic field data from measurement points resembling data from multi-spacecraft flying though a reconnecting current sheet is used to check both techniques to deduce a proper normal vector. We examine discharges with the two-dimensional (2-D) X-line structure as well as cases in which a flux rope forms within the layer. All discharges are in a two-fluid regime in which electrons are magnetized but not ions. Boundary-crossing time analysis with four sample measurement points forming a tetrahedron generates a reasonable unit normal vector and relative velocity along the normal vector for all of the tested cases. On the other hand, MVAB sometimes fails to predict a proper normal direction. This is because the X-line magnetic geometry is fundamentally 2-D or 3-D. However, the direction along the reconnecting field determined by MVAB does not deviate much from the real magnetic geometry documented by 2-D magnetic probe arrays and one additional probe at a different toroidal location. Based on these observations, we suggest a procedure for determining a local coordinate system for data from the Magnetospheric Multi-Scale (MMS) mission when spacecraft passes through a reconnecting current sheet. The distance between measurement points on the order of the ion skin depth (c/{omega}{sub pi}) is pertinent to determination of the magnetic geometry.