The STEREO SWEA experiment is made of two identical electron instruments placed on a 4.5 m boom in the shadow of each of the two STEREO spacecraft, which orbit around the Sun. Each instrument is composed of an electrostatic analyzer with a 360° planar field-of-view, perpendicular to the Sun-Earth direction, and divided into 16 anodes of 22.5° each. The entrance deflection system permits to increase the instrument field-of-view to +/- 65° away from the detection plane by steering the arrival direction of the particles (typically in 6 directions). The three-dimensional particle distribution functions are obtained in just 2 s in burst mode, but data is regularly available at a 30 s cadence. The full SWEA description is provided in Sauvaud et al. (Space Sci. Rev., 2008).
IRAP, with the support of CNES, has contributed hardware to the mission through the provision and calibration of the two detector heads, comprising all the mechanics of the analyzer, front-end electronics, and high-voltages. The electronics box comprising the control and power electronics was built by the Space Sciences Laboratory in Berkeley.
Development Institution: Space Sciences Laboratory, Berkeley (PI: J. Luhmann), IRAP (CoI : J.-A. Sauvaud)