Fundamental Concepts Associated with Magnetic Reconnection

Abstract

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, “frozen-in” 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 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.