Early Observations from the Solar Orbiter SWA/Electron Analyser System

Abstract

<p>Solar Orbiter carries a total of 10 instrument suites making up the payload for the mission. &#160;One of these, the Solar Wind Analyser (SWA) instrument, is comprised of 3 sensor units which are together served by a central DPU unit. &#160;Of particular focus in this presentation are the early measurements from one of these sensors, the Electron Analyser System (EAS). &#160;EAS is a dual-head, top-hat electrostatic analyser system that is capable of making 3D measurements of solar wind electrons at energies below ~5 keV from a vantage point at the end of a 4-metre boom extending into the shadow of the spacecraft. &#160;The sensor was accommodated in this location to both maximise the unobstructed field of view and to minimise the effect of spacecraft related disturbances on the low-energy (less than a few tens of eV) electrons expected the core population of the solar wind.</p><p>To date the SWA instrument sensors have operated sporadically during the mission cruise phase, which began in June 2020. &#160;This is due to a number of operational issues faced by the SWA team, which mean we have not been able to take data in a continuous manner. &#160;However, the data that has been taken shows the clear promise of the SWA measurements, in general, once these issues can be overcome. &#160;For example, EAS is using a novel sample steering mechanism in burst mode which, with reference to a magnetic field vector shared onboard by the MAG instrument, allows the capture of the electron pitch angle distribution at unusually high time resolution. &#160;We discuss these observations here, and illustrate the potential science returns from the burst mode. &#160;We also present results from the new EAS observations in the vicinity of reconnecting current sheets in the solar wind, to more generally illustrate the capability of the sensor.&#160;</p>