Current starvation and relativistic magnetic reconnection: an old idea of present interest

Abstract: In an ultra-relativistic plasma regime, magnetic reconnection may take completely different features due to the relativistic limit on the particle velocity. Conditions can be realized when the spatial variation of the magnetic field cannot be balanced by the electron current in Ampere’s law. In this case the standard MHD description fails, and the magnetic field dynamics is dominated by the displacement current and by the corresponding inductive electric field. These conditions correspond to the so-called dynamic dissipation regime first proposed by S.I. Syrovatskii nearly 60 years ago in the context of Cosmic Physics. Recently this regime has become of interest also in the context of relativistic laboratory plasmas.