Proton acceleration during the interaction of magnetic structure with interplanery shock

We report the energetic proton dynamics around an interplanetary shock driven by a coronal mass ejection (CME). We use the high-resolution EPT instrument onboard the Solar Orbiter to study the local acceleration process of energetic protons. The interplanary shock is observed by the Solar Orbiter on March 14th 2023 at 0.6 au. A magnetic structure is also present 7-minute upstream the shock. The magnetic structure manifests as a B_N reservsal and mangetic depression with asymmteric magnetic magnitude on each side. A detailed analysis suggests that the magnetic structure is possibly related to a magnetic reconnection. The magnetic reconnection region is partially crossed by the Solar Orbiter, which passes through the reconnection upstream, the diffusion region and an extended exhaust region in sequence. Upstream the structure, the proton differential flux anisotropy is constant which is dominated by the parallel-propagating energetic protons from the shock. Interestingly, a bipolar-like flux anisotropy is present between the magnetic structure and the shock, while B_R>0 is satisfied all the time. This suggests that some local physical processes may play a role in proton acceleration due to the presence of magnetic reconnection. We also compare the flux spectra upstream and downstream the structure, the spectral indices of which are very different. Our work highlights the importance of magnetic structures/reconnection in particle acceleration, even when the structure is close to the shock.