Miniaturized electron magnetic spectrometer

Traditionally magnetic electron spectrometers provide the most reliable electron measurements in space at energies above similar to10 keV. However, the inclusion of powerful magnets presents problems for spacecraft with stringent magnetic cleanliness requirements, and the magnetic yoke required to close the magnetic flux close to the instrument is bulky and heavy. To mediate the aforementioned shortcomings, we report a preliminary conceptual design on a new miniature magnetic electron spectrometer that measures energetic electrons from 50 keV to 1.5 MeV. The new detector covers close to 360degrees in the azimuthal direction and +/-3degrees off the plane, and if mounted on a spinning spacecraft, will measure the full spherical angular distribution twice per spin. This represents a very large advance over previous designs, which typically measure a very limited angular cone at any one time. As a result of the placement of the magnets in this design, the magnetic flux closes intrinsically, hence no bulky flux-containing magnetic yoke, typical in previous magnetic electron spectrometer designs, is required. We are funded by a NASA instrument development grant to develop a prototype of this sensor over the next 2 years. (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.