Resistive instabilities and field line reconnection

Laboratory plasma devices are generally designed with ideal magnetohydrodynamic stability in mind, so it is not surprising that the next most rapid class of modes, the resistive instabilities, figure prominantly in the description of the behaviour of the plasmas achieved. In this chapter the linear and nonlinear plasma behaviour associated with simple scalar resistivity are reviewed. The notions of the existence of magnetic surfaces, the coupling of field and plasma, and the relaxation of this strict coupling brought about by finite scalar resistivity, are reviewed. The linear theory of reconnection for a plane current layer is reviewed. Then the nonlinear theory of tearing-mode development and the implications for understanding toroidal magnetic confinement devices is reviewed. Finally, the implications of the presence of a background of small magnetic islands are considered. (Auth.)