High-Time-Resolution Mirror Langmuir Probe Diagnostics for Transient Plasma Measurements in the MUSE Stellarator

Accurate measurements of plasma parameters in evolving or spatially localized regions are essential for understanding magnetic confinement devices. In the MUSE compact stellarator, this need will be addressed through a high-time-resolution diagnostic system based on the Mirror Langmuir Probe (MLP) [1]. Unlike double-tip probes, the MLP rapidly switches between pre-selected bias voltages, enabling precise, time-resolved measurements of electron temperature, electron density, and floating potential with a single probe tip —crucial for studying the core, edge, and scrape-off layer (SOL) regions.

Our system is based on an FPGA implementation of the MLP developed by Vincent et al. [2]. Contributions were focused on ensuring the robustness of the control and data acquisition software. Errors were diagnosed and resolved, the codebase was rebuilt within a Linux virtual machine using the Koheron make system, and the FPGA implementation was deployed to hardware. These efforts are essential for verifying system functionality and for integration of the MLP into the MUSE platform, enabling high-fidelity measurements of transient plasma dynamics.

This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-09CH11466 and funded by the Summer Undergraduate Laboratory Internship (SULI) program.