Authors: Tyler Eddy (University of Michigan, Aidan Nakhleh (University of Michigan), Ryan Dewey (University of Michigan), Susan Lepri (University of Michigan), and Jim Raines (University of Michigan)

The Heavy Ion Sensor (HIS) is a time-of-flight plasma spectrometer onboard Solar Orbiter that measures the heavy ion populations (He, C, O, Mg, Si, and Fe) and their charge state distributions between 0.5- 75 keV/e. The velocity distribution functions (VDFs) of heavy ions carry critical information pertaining to anisotropies with respect to the magnetic field that lead to instabilities that determine the different thermal states found within the fast and slow solar wind. To date, 3D VDFs of heavy ions beyond helium have never been resolved in the solar wind. We present our ongoing efforts to calibrate the VDFs of protons, helium, and, for the first time, oxygen ions within the solar wind. The processes developed will provide the pipeline for future production of heavy ion VDFs measured by the Heavy Ion Sensor.