Fundamental Concepts Associated with Magnetic Reconnection

The chapter starts with a discussion about the importance of the concept of magnetic field lines in space plasmas and magnetic reconnection, followed by presentations on: (a) the meaning and validity of empirical constructs related with magnetic reconnection research, such as: “moving” magnetic field lines, “frozenin” condition and “diffusion region” of reconnection; and (b) experimental evidence of the diffusion region and related energetics. Next, aims to link external (MHD) with internal (non-MHD) regions of reconnection are discussed in association with W.D. Gonzalez ( ) • D. Koga National Institute for Space Research (INPE), São José dos Campos, São Paulo 12227-010, Brazil e-mail: [email protected] E.N. Parker Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637, USA F.S. Mozer Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA V.M. Vasyliūnas Max-Planck-Institut für Sonnensystemforschung, Göttingen 37077, Germany P.L. Pritchett Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547, USA H. Karimabadi SciberQuest, Inc., Del Mar, CA 92014, USA CureMetrix, Inc., Rancho Santa Fe, CA 92067, USA P.A. Cassak Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506, USA J.D. Scudder Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA M. Yamada • R.M. Kulsrud Center for Magnetic Self-Organization, Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08544, USA © Springer International Publishing Switzerland 2016 W. Gonzalez, E. Parker (eds.), Magnetic Reconnection, Astrophysics and Space Science Library 427, DOI 10.1007/978-3-319-26432-5_1 1 2 W.D. Gonzalez et al. the so-called “Axford conjecture”, followed by short presentations on: (a) global equilibria in reconnection; and (b) the role of the separatrices in global aspects of reconnection. In the last section, we present additional discussion about the concept of “diffusion region” and about the two fundamental questions associated with magnetic reconnection reviewed in this chapter.