AbstractThe reconnection current layer thickness is expected to scale with either the ion inertial length or the ion gyroradius. Both of these quantities scale with the mass of the ions present. During geomagnetically disturbed times, the reconnection layer in the magnetotail can contain a significant amount of O+. Using Cluster multi‐spacecraft measurements, we have studied nine reconnection events in the magnetotail plasmasheet, to determine whether the reconnecting current sheet thickness scales with the ion gyroradius or the ion inertial length, and whether the amount of O+ in the plasma sheet has an effect on the current layer thickness. We find that the thickness is equal to the H+ gyroradius, even when the plasma sheet has a high O+ content. This result is in contrast to Hall MHD expectations and likely results from the multiscale nature of the current sheet.
