MAGNETIC RECONNECTION IN COLLISIONLESS FIELD REVERSALS THE UNIVERSALITY OF THE ION TEARING MODE

A theoretical analysis of the stability of a quasi-neutral sheet with small normal magnetic component B(n) is presented. It is demonstrated that contrary to the statement of Pellat et al. [1991], pitch angle diffusion (PAD) can remove the stabilizing effect of B(n). The PAD results in the escape of electrons to the region of negligibly small wave--particle interactions which decreases the electron contribution to the energy balance equation. In the limit of strong PAD the ion tearing mode growth rate gives the universal upper estimate of the rate of collisionless spontaneous reconnection.