Assessing the Performance of the Solar Orbiter Heavy Ion Sensor via Cross Calibration with its Ion Optical Model

We report our methods and findings comparing the calibration of the Solar Orbiter Heavy Ion Sensor (SO-HIS) spaceflight instrument using laboratory measurements to that of its SIMION ion optical model counterpart. For any instrument, the flight model, flight spare, and engineering model each requires its own calibration in the laboratory due to manufacturing and integration differences. Similarly, the ion optical model will not be identical to a manufactured instrument due to these and other factors, such as model resolution, that will cause slight differences in behavior under identical conditions. While it is impossible to test all instrument configurations in the lab, it is critical to understand the response of the instrument under all conditions. Therefore, having an ion optical model of the instrument that can provide a similar instrument response proves a uniquely useful tool in determining instrument characterization, such as geometric factor (GF), under arbitrary conditions. Thus, to both achieve the benefits of having an ion optical model available on the ground and to maintain reasonable assurance of the transferability of instrument characterizations between the two, it is critical to perform a comparable calibration on both and assure that the responses are similar. We perform a voltage calibration on the ion optical model and then compare instrument responses using calculated GFs for both the laboratory instrument and ion optical model. We report here the first cross calibration for SO-HIS between spaceflight instrument and ion optical model.