SH036-0014
The Solar Orbiter Fast Ion Spectrometer PAS in-flight calibration and the first "ready for scientific use" data.
The Solar Orbiter Fast Ion Spectrometer PAS in-flight calibration and the first "ready for scientific use" data.
Monday, 14 December 2020
Poster
Abstract:
Solar Orbiter is an ESA/NASA mission that provides an unprecedented opportunity to discover the fundamental connections between the rapidly varying solar atmosphere and the solar wind. The mission was launched in February 2020 and is now providing data in the "cruise mode", when "in situ" instruments are permanently active. The Solar Wind Analyzer (SWA) plasma package is one of the "in situ" instruments, providing comprehensive measurements of the solar wind. In particular, the Proton-Alpha Spectrometer (PAS) is performing high time resolution measurements of the ion flow as 3D distribution functions, providing plasma density, plasma bulk velocity and temperature. PAS can sample up to 13 3D ion distribution functions per second. The instrument is continuously ON since July 2020.
To convert the raw PAS data to the physical 3D distribution functions, we need to perform an intensive in-flight calibration of the instrument. The detection efficiency of the PAS detectors at the very low deep space temperatures can be different from the properties measured during the ground calibration. To determine the real "in-flight" efficiency of detectors we use several approaches as follows: 1) comparison of PAS data with the density derived from the local plasma frequency measurements made by the RPW wave instrument, 2) comparison of PAS data with the data from the EAS electron spectrometer, 3) comparison of PAS angular bins during spacecraft rotation, 4) PAS 3D distribution function shall by gyrotropic in steady cases, and 5) PAS response from numerical simulations, and . All these efforts provide a stable procedure of PAS in-flight data calibration. The present paper shows the first examples of PAS "ready for scientific use" obtained in the high fluctuating solar wind flow.
To convert the raw PAS data to the physical 3D distribution functions, we need to perform an intensive in-flight calibration of the instrument. The detection efficiency of the PAS detectors at the very low deep space temperatures can be different from the properties measured during the ground calibration. To determine the real "in-flight" efficiency of detectors we use several approaches as follows: 1) comparison of PAS data with the density derived from the local plasma frequency measurements made by the RPW wave instrument, 2) comparison of PAS data with the data from the EAS electron spectrometer, 3) comparison of PAS angular bins during spacecraft rotation, 4) PAS 3D distribution function shall by gyrotropic in steady cases, and 5) PAS response from numerical simulations, and . All these efforts provide a stable procedure of PAS in-flight data calibration. The present paper shows the first examples of PAS "ready for scientific use" obtained in the high fluctuating solar wind flow.