The Solar Wind Electron (SWE) Instrument for the Interstellar Mapping and Acceleration Probe Mission

The Solar Wind Electron (SWE) instrument of the Interstellar Mapping and Acceleration Probe (IMAP) mission is designed to measure the in situ solar wind thermal and suprathermal electrons at the spacecraft. SWE contributes to the IMAP science objective to understand particle injection and acceleration processes near the Sun and in the heliosphere and heliosheath, and provides context for the IMAP measurements of energetic neutral atoms from the outer heliosphere. SWE measures the solar wind thermal and suprathermal electron distribution from 1-5000 eV in 24 log-spaced steps with energy resolution $\Delta$ E/E of 14%. Electrons are measured at 7 polar angles relative to the spacecraft spin axis using 7 CEM detectors, and in 30 spin angle bins, giving coverage over ∼95% of phase space as the spacecraft spins. A subset of SWE measurements are transmitted in near real time as part of the IMAP I-ALiRT system, providing the first real time identification of counterstreaming solar wind electrons. We describe the SWE instrument design and performance, and SWE operations and data processing.