Multifluid model of a one-dimensional steady state magnetotail current sheet

The central current sheet of the magnetotail has been modeled frequently as a nearly one‐dimensional configuration that might have a significant role in magnetospheric physics as a site of particle acceleration. Yet comparisons of data with tail models have mainly used the Harris solution in spite of its deficiencies: No normal magnetic field, uniform cross‐tail drift, and vanishing asymptotic plasma density. We present a time‐independent one‐dimensional multifluid model that separates ions into groups coming from sources above and below the current sheet. Electrons are a separate group. A disadvantage is that equations of state are required for closure. The isotropic pressure equation of state is supported by observation and gives reasonable results. This model is more realistic; it encodes more information than a single fluid or an ion and electron fluid model. This fluid model can be easily used to compare with magnetotail data. Field and plasma moment data provide boundary conditions for a model calculation. We examine symmetric models that predict specific relations between various quantities, such as magnetic field or density. Solutions are obtained similar to Harris' model, but with non‐uniform out‐of‐plane ion flow and non‐vanishing asymptotic density. Sheet thickness has weak dependence on the normal magnetic field and modest dependence on electron‐to‐ion pressure ratio. The ratio of sheet center to asymptotic density decreases with asymptotic ion pressure. This one‐dimensional configuration of the current sheet, in Earth's reference frame, provides an example of conversion of electromagnetic energy into fluid energy.