Studies of Magnetic Reconnection in Laboratory and Space-Astrophysical Plasmas
Masaaki Yamada
Recently magnetic reconnection phenomenon have been recognized to have wide-ranging importance in space and astrophysical plasmas, as a key process in the interaction of the solar wind with the dipole field of the earthfs magnetosphere, in the evolution of solar and stellar flares and in the formation process of stars. The recent advances in laboratory reconnection physics, along with the surge of space physics data from satellites, have made cross-discipline research very useful for obtaining new physics understanding of its key processes [1]. The recent rapid advance of numerical simulation has played an important role in bridging between laboratory data and space-astrophysical observations [2]. One of the most fundamental questions is why reconnection occurs much faster than predicted by the classical MHD (Magnetohydrdynamic) theory. MRX (Magnetic Reconnection Experiment), together with other laboratory experiments, is dedicated to the study of reconnection physics in a controlled manner [1,3]. Many important findings to date include 1) the measured reconnection rate decreases notably with presence of guide field, 2) resistivity is classical in the collisional regime but is strongly enhanced at low collisionality, 3) the presence of electromagnetic turbulence in the lower-hybrid frequency range during fast reconnection, and 4) first clear measurements of the predicted quadrupole out-of-plane magnetic field. The results from dedicated laboratory experiments depict many striking commonalities with observations in the magnetosphere sheath [3,4]. The recent experimental verification of Hall MHD effects in a neutral sheath of the width of the ion skin depth depicts a good example [5]. This talk provides a brief review of primary results from laboratory experiments by addressing both the global and local issues for magnetic reconnection together with comparison of the laboratory data with recent space astrophysical observations. Finally possible collaborative research subjects with the Solar-B program will be discussed.
Collaboration with H Ji, S. Gerhardt, R. Kulsrud, M. Inomoto, A. Kuritsyn, Y. Ren,
1. M. Yamada, Earth Planets Space v.53, 539 (2001) and reference there in,
2. M.A. Shay and J.F. Drake, Geophys. Res. Lett. 25, 3759 (1998)
3. M. Yamada et al., Phys. Plasmas 7, 1781 (2000)
4. F. Mozer et al., Phys. Rev. Lett 89, 15002-1 (2002)
5. Y. Ren et al., Phys. Rev. Letts. V.95 05503 (2005)
Correspondence
Masaaki Yamada (myamada@pppl.gov), Princeton Plasma Physics Laboratory, Princeton University, Princeton New Jersey 08543
presentation
invited