Forced Magnetic Reconnection at a Neutral X-Point

The response of a two-dimensional X-type neutral point magnetic field to a quasi-static perturbation is considered. The latter is specified by a redistribution of the magnetic flux at a circular boundary centered on the neutral point. A special role of the dipole (m = 1) azimuthal perturbation component is revealed as the only one that results in the formation of a current sheet and subsequent magnetic reconnection. The excess magnetic energy released by such reconnective relaxation is also derived.