Formation of thin current sheets in a quasistatic magnetotail model

Abstract

Observations suggest that thin current sheets forming in the near‐Earth magnetotail late in substorm growth phases may be a crucial part of substorm evolution. In a simple theoretical model the current density was shown to become singular for suitable external perturbations. Here, we address the same problem in a more realistic model based on the adiabatic MHD ‐ theory developed by Schindler and Birn [1982]. We show that under suitable conditions the formation of a thin current sheet in the near‐Earth tail is an intrinsic aspect of flux transfer to the magnetotail. The mechanism is based on the strong variation of flux tube volume with the magnetic flux function.