The IMPACT Solar Wind Electron Analyzer (SWEA)

Abstract

SWEA, the solar wind electron analyzers that are part of the IMPACT in situ investigation for the STEREO mission, are described. They are identical on each of the two spacecraft. Both are designed to provide detailed measurements of interplanetary electron distribution functions in the energy range 1∼3000 eV and in a 120°×360°solid angle sector. This energy range covers the core or thermal solar wind plasma electrons, and the suprathermal halo electrons including the field-aligned heat flux or strahl used to diagnose the interplanetary magnetic field topology. The potential of each analyzer will be varied in order to maintain their energy resolution for spacecraft potentials comparable to the solar wind thermal electron energies. Calibrations have been performed that show the performance of the devices are in good agreement with calculations and will allow precise diagnostics of all of the interplanetary electron populations at the two STEREO spacecraft locations.

STEREO and Wind observations of intense cyclotron harmonic waves at the Earth's bow shock and inside the magnetosheath

“…In general, particle data are not available to facilitate this identification because the STEREO spacecraft were still in the commissioning phase during this time and the instruments were not fully operational. Despite this, flux levels are high enough on a few of the crossings that data from the Solar Wind Electron Analyzer (SWEA) [Sauvaud et al, 2008] were used to corroborate the identification of the bow shock crossing.…”

Multi-Spacecraft Observations: Stream Interactions and Associated Structures

“…This is also confirmed by the change of the suprathermal-electron pitch angle distribution (not shown) from IMPACT Solar Wind Electron Analyzer (SWEA, Sauvaud et al, 2008). Since the coronal field neutral line was about 10°north in Figure 1 (1), the crossing of HCS at STA and STB, both in the southern hemisphere, indicates a moderate inclination of the HCS.…”

The IMPACT Solar Wind Electron Analyzer (SWEA): Reconstruction of the SWEA Transmission Function by Numerical Simulation and Data Analysis

“…As part of the In situ Measurements of Particles and CME Transients (IMPACT) experiment (Luhmann et al 2008), the Solar Wind Electron Analyzer (SWEA) instruments (Sauvaud et al 2008) provide in situ electron measurements at both STEREO spacecraft. The SWEA instruments are hemispheric top-hat electrostatic analyzers (Carlson and McFaden 1998) with deflector plates mounted at the aperture and with microchannel plate (MCP) detectors.…”

“…In particular, it focuses on problems with the detection of electrons below 50 eV, apparent when the STEREO spacecraft are in heliocentric orbit, which in turn limit the availability of thermal core electron parameters. The primary SWEA measurements at the higher energies which are used for detecting the electron halo and strahl (heat flux) (Rosenbauer et al 1997) populations are not affected, and are available as described in the earlier report by Sauvaud et al (2008).…”