Authors: Sarah A. Spitzer (University of Michigan), Susan T. Lepri (University of Michigan), Jim M. Raines (University of Michigan), Frederic Allegrini (Southwest Research Institute), Connor P. Raines (University of Michigan), Austin N. Glass (University of Michigan), Jason A. Gilbert (University of Michigan), Stefano Livi (Southwest Research Institute & University of Michigan)

Solar Orbiter was launched on 9 February, 2020 as a collaborative effort between ESA and NASA, and is an instrumental mission utilizing both remote sensing and in situ measurements to study how the Heliosphere is created and shaped by the Sun. Solar Orbiter provides a unique opportunity to observe the Sun away from its equator, reaching orbits as close to the Sun as ~2.8 AU at up to around 30 degrees out of the ecliptic in the extended mission. The Solar Orbiter Heavy Ion Sensor (SO-HIS) is an in situ triple-coincidence ion mass spectrometer intended to measure ion and elemental composition as well as 3D velocity distribution functions of ions in the range of He ‒ Fe with charge-states from He+ to Fe20+ in the full energy-per-charge (E/q) range 0.5 ‒ 80 keV/e. SO-HIS measures the bulk solar wind in the range 0.5 ‒ 18 keV/e and the suprathermal solar wind components of He, C, O, and Fe up to at least 60 keV/e in addition to pickup ions. SO-HIS uses 64 E/q steps with an energy resolution of 6 ‒ 10% and 16 elevation steps in the range +/-17 degrees with an angular resolution of <3.5 degrees and has a continuous azimuthal acceptance in the range -30 ‒ +66 degrees. We create a high resolution ion optical model (IOM) of the SO-HIS instrument from its CAD model using the SIMION software to characterize the instrument, specifically to determine the geometric factor (GF) under any instrument configuration. After validating SIMION outputs against laboratory measurements and presenting a function of the instrument’s GF under standard solar wind conditions, we now expand this study to include higher energy ions as well as angles outside the radial solar wind direction.