One‐dimensional hybrid simulations of current sheets in the quiet magnetotail

Hybrid simulations (kinetic ions, massless fluid electrons) have been performed of the magnetotail current sheet for parameters characteristic of the quiet magnetotail (υD, bn < 1). Here bn = Bn/B0,υD = (cEy/Bn)/υi,Bn is the north / south (z) magnetic field, B0 the asymptotic value of the tailward (x) field and υi the ion thermal speed, where the magnetospheric coordinate system is used. It is shown that the current sheet is more stable than in previously examined cases with high υD and / or large bn. A clear single reversal in Bx persists over the entire simulation and a By component is created, with a slow rate of growth (hundreds of Ωi−1, where Ωi = eB0/miC). This is many minutes in real time. It is suggested that the waves are due to an electromagnetic instability of the cross‐field ion current.