Iron Heating Across a Shock Observed by Solar Orbiter's Heavy Ion Sensor

<p>Ion mass-per-charge and shock geometry determine both shock injection and the number of times a charged particle is reflected across a shock. As such, they govern charged particle acceleration and heating at shock. Solar Obiter&#8217;s Heavy Ion Sensor (HIS) observed a quasi-parallel CME-driven shock on March 11, 2022. HIS has sufficient time, mass, and charge resolution that it measured individual distributions of iron 8+ through 12+ on the variable timescale of 2 to 5 minutes. Using these 1D velocity distribution functions (VDFs), we report that the thermal portion of the Fe distribution heats across the shock, that this heating increases with Q/M, and the heating increases with distance downstream from the shock.</p>