Upgrade of the high-field side divertor Langmuir probe diagnostic system in J-TEXT tokamak

Langmuir probes on divertor target plates play a crucial role in studying boundary plasma parameters and phenomena such as divertor detachment. Former experimental results on J-TEXT tokamak indicate that, due to the steep heat flux gradient in the near-SOL region, the previously sparse Langmuir probes on the high-field-side (HFS) divertor target plate failed to capture the poloidal variation characteristics accurately. Therefore a newly designed Langmuir probe diagnostic system with high poloidal resolution has been constructed in the HFS divertor target plate, whose design addresses the magnetic flux line blockage at different poloidal positions through a segmented probe layout, and resolves installation space constraints and structural interference issues via an integrated mounting structure. Preliminary experimental results indicate that, benefiting from the improved poloidal spatial resolution, the new system is capable of measuring the spatial distributions of boundary physical parameters, including strike point positions and heat flux decay lengths on the target plate.