Thermal Analysis and Engineering Design of Nonintercepting Wire Calorimeters in the Photo-Neutralization Experiment Platform (PNEP)

To advance the development of neutral beam injection technology, a photo-neutralization experimental platform (PNEP) based on negative hydrogen ions (30 keV, 2 mA) is under construction at the Comprehensive Research Facility for Fusion Technology. As a key step in validating the feasibility of photo-neutralization, the beam’s shape, size, and spatial uniformity are crucial for matching the laser spot and enhancing neutralization efficiency. A tungsten-based wire calorimeter provides a nonintercepting diagnostic approach that can be directly exposed to the beam. This diagnostic enables online qualitative assessment of the beam spot shape and uniformity, and after electrical calibration, offers quantitative measurements of the beam power density. In this study, we design a wire calorimeter tailored for the PNEP and systematically investigate its performance characteristics, as well as the influence of major design parameters, through detailed thermodynamic simulations. The results establish a theoretical foundation and design reference for subsequent installation, commissioning, calibration experiments, and beam power distribution measurements of the wire calorimeter at the PNEP.