Modelling the Geometric Structure of the Magnetic Field in the Nightside Magnetosphere

• Other Authors: Sofko, George J.
• Language: English
• Published: 2015
• Subjects: stretched magnetic field lines; nightside magentosphere; model of magnetic field lines; current systems in magnetotail
• Online Access: http://hdl.handle.net/10388/ETD-2013-03-1448

In this thesis, a simple model of the stretched magnetic field lines in the nightside magnetotail was created. The nightside magnetosphere model contains four main regions: plasmasphere, plasma sheet, magnetic lobes, and low latitude boundary layers. The plasma sheet is split into three regions based on the shape of the closed field lines present: dipole plasma sheet, transition plasma sheet, and stretched plasma sheet (SPS). The SPS, the focus of this thesis, is split into two regions: disruption zones (DZs) and a central neutral sheet (NS). The shape of the stretched field lines contain four inflection points. The convex curvature regions form the DZs and the central concave curvature region forms the NS. The NS is split into two regions: outer neutral sheet (ONS) and inner neutral sheet (INS). Due to the reversal of the x-component of the magnetic field at the center line of the NS, the protons are magnetized in the ONS and "unmagnetized" in the INS. There are two main current systems in the SPS. The first is a double vortex current system consisting of eastward current in the DZs that closes westward in the NS. The second system is the NS field-aligned current (FAC) system. It is generated in the INS mainly by the earthward convective drift of the electrons while the "unmagnetized" protons have little convective drift and remain tailward of the electrons. This FAC system produces the pre-onset electron auroral arc during the growth phase of the substorm. A simple model of the stretched magnetic field lines was created in order to calculate the current systems present in the SPS. The simple model was based entirely upon the shape of the stretched field lines. It passed two physical tests, divergence of the magnetic field and limits at infinity, so it was used to calculate currents. The total current using Ampere's law and the curvature current was found. Both results agreed with the double vortex current system.