Laboratory Studies of the Physics of Two-Fluids MHD for Magnetic Reconnection 

Masaaki Yamada*, Princeton Plasma Physics Laboratory, Princeton University, 
Princeton New Jersey 08543, myamada@pppl.gov

The recent advances in laboratory reconnection physics, along with the surge of space 
physics data from satellites, have made cross-cutting research very useful for obtaining 
new physics understanding of its key processes. Also the recent rapid advance of 
numerical simulation has played an important role to bridge laboratory data with space-
astrophysical observations [1]. Recently the two-fluids MHD physics issues for 
reconnection dynamics have been intensively investigated in both 2-D and 3-D 
geometries. The results from dedicated laboratory experiments on magnetic 
reconnection [2] depict many striking commonalities with the observations in the 
dayside and tail-side magnetosphere sheaths [3,4]. This paper provides a brief review of 
the most recent results from MRX [Magnetic Reconnection Experiment] [5-7] which 
address two-fluid physics issues for magnetic reconnection as well as comparison of the 
MRX data with the recent space observations. We report observation of an out-of plane 
quadrupole magnetic field during magnetic reconnection[7]. This experimental 
verification of Hall MHD effects has been carried out in the MRX neutral sheath of the 
ion skin depth (c/omega_pi). To our knowledge, this is, to date, the clearest identification of the 
quadrupole magnetic field in the neutral sheet of a laboratory plasma. The next series of 
research will be devoted to quantitative evaluation of this field and its effects, 
particularly the relationship of this fields with the magnetic fluctuations which correlate 
well with the enhanced resistivity [6]. 
In collaboration with Y. Ren, S. Gerhardt, H. Ji, R. Kulsrud, A. Kuritsyn,
Work supported by DOE, NASA, and NSF


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4. T. D. Phan et al.,  Nature, 404:848, (2000).
5. M. Yamada et al., Phys. Plasmas 7, 1781 (2000)
6. H. Ji et al.,  Phys. Rev. Letts. V.92, 115001 (2004)
7. Y. Ren et al., Submitted to Phys. Rev. Letts. (2005)