Plasma flow at the magnetopause
Warren, Carlos Scott
Freeman, John W., Jr.
Master of Science
On January 13 and 14, 1967, an unusual compression of the magnetosphere during an intense magnetic storm caused the magnetopause to pass inside the orbit of the geostationary spin-stabilized satellite ATS-I. At the time of the boundary crossing, the satellite was located at 6.6 earth radii, approximately two hours past the noon meridian on the dusk side. The boundary crossing was marked by rapid magnetic field changes at the satellite position, and anomalously high anisotropic ion fluxes detected by the on-board Rice suprathermal ion detector. The Rice ion detector samples fluxes in the equatorial plane of the earth, in approximately 12° increments. There are 20 differential energy passbands covering 0-50 ev and two integral passbands that sample energies > 0 ev and >50 ev. A complete energy spectrum is covered in 112 seconds, while a 360° angular scan is completed in approximately 0.64 seconds. During the almost one hour the magnetopause was in the satellite's vicinity, several fluctuations in the local magnetic field and ion directional distributions indicated multiple boundary crossing by the ATS-I. In addition to the pure magnetosheath and pure magnetospheric ion flow patterns, a new component of ion flow was found close to, inside of, and along the magnetospheric boundary. The streaming energy of this flow along the boundary was less than that observed in the magnetosheath, but greater than that observed in the pure magnetosphere. This new component is thought to be the "return" flow (to the tail) for the magnetospheric thermal plasma found to be convecting sunward at points deeper within the magnetosphere.