2015-04-07 14:15:55.0 [mpmorahan] insert AltLabel (id: null text: Electron Drift Instrument language code: en); insert Definition (id: null text: The Electron Drift Instrument measures both the electric and magnetic fields by tracking the path of electron beams through space. EDI sends a beam of electrons out into space using each of its two Gun Detector Units. In the presence of magnetic fields, electrons travel in orbits that are nearly circles, so over the course of about half a mile, the electron beam curves around on itself until it comes back in to the second Gun Detector Unit. By measuring how long it takes the electrons to circle back, one can calculate the strength of the magnetic fields through which the beam traveled. When electric fields are present as well, the electron beam will not make a perfect circle, but will drift in a predictable way as it returns. By measuring the size of that sideways drift, one can calculate the strength of the electric fields. This technique of correctly capturing the electron beam was successfully demonstrated by the joint European Space Agency/NASA Cluster mission. On MMS, the EDI will take faster measurements than on Cluster. Its strength, however, is not in its speed but in its precision. Knowing the displacement of the particles in space due to an electron field is crucial for accurate measurements by other instruments aboard MMS. If needed, EDI can also be used solely as a detector, measuring all incoming electrons from space as opposed to just tracking its own specialized electron beam. In this case, EDI can make observations at rates of up to 1,000 times a second. The EDI electron gun was developed at the Space Research Institute. EDI optics were developed at the University of Iowa. The sensitive detector, the controlling electronics, and the overall integration and operation of the EDI instrument is the responsibility of the University of New Hampshire in Durham. language code: en);
Gun Detector
MMS EDI
The Electron Drift Instrument measures both the electric and magnetic fields by tracking the path of electron beams through space. EDI sends a beam of electrons out into space using each of its two Gun Detector Units. In the presence of magnetic fields, electrons travel in orbits that are nearly circles, so over the course of about half a mile, the electron beam curves around on itself until it comes back in to the second Gun Detector Unit. By measuring how long it takes the electrons to circle back, one can calculate the strength of the magnetic fields through which the beam traveled. When electric fields are present as well, the electron beam will not make a perfect circle, but will drift in a predictable way as it returns. By measuring the size of that sideways drift, one can calculate the strength of the electric fields. This technique of correctly capturing the electron beam was successfully demonstrated by the joint European Space Agency/NASA Cluster mission. On MMS, the EDI will take faster measurements than on Cluster. Its strength, however, is not in its speed but in its precision. Knowing the displacement of the particles in space due to an electron field is crucial for accurate measurements by other instruments aboard MMS. If needed, EDI can also be used solely as a detector, measuring all incoming electrons from space as opposed to just tracking its own specialized electron beam. In this case, EDI can make observations at rates of up to 1,000 times a second. The EDI electron gun was developed at the Space Research Institute. EDI optics were developed at the University of Iowa. The sensitive detector, the controlling electronics, and the overall integration and operation of the EDI instrument is the responsibility of the University of New Hampshire in Durham.