The Electron Drift Instrument (EDI) on MMS: Measurement Technique and Initial Results from Convection Studies in the Outer Magnetosphere
Thursday, October 1, 2015
Hans Vaith1, Roy B Torbert1,2, Ivan Dors1, Matthew R Argall1, Craig Kletzing3, Scott R Bounds3, Wolfgang Baumjohann4, Rumi Nakamura4, Manfred Steller4, Werner Magnes4 and Christopher T Russell5, (1)University of New Hampshire, Durham, NH, United States, (2)Southwest Research Institute Durham, Durham, NH, United States, (3)University of Iowa, Iowa City, IA, United States, (4)Space Research Institute, Austrian Academy of Sciences, Graz, Austria, (5)University of California Los Angeles, Los Angeles, CA, United States
Abstract:
EDI measures the displacement of electrons after one or more gyrations in the ambient magnetic field. From this displacement, the drift velocity can be calculated if the electron gyro time is known. The technique requires the injection of two electron beams in the plane perpendicular to the magnetic field and the search for those directions within that plane that return the beams to their associated detectors. The displacement, also called drift step, can be calculated from either triangulation of the recorded firing directions of the beams or from the electron times-of-flight between emission and detection. The two analysis methods are complementary in that triangulation is more accurate at small drift steps, whereas the time-of-flight method yields better results for large drift steps where the triangulation problem deteriorates. We present the measurement technique and first results from convection studies in the outer magnetosphere using EDI data from MMS.
