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Abstract The precise and continuous measurement of reactor core temperature is crucial for the safe and efficient operation of light water reactors. Current sensor technologies are limited in their capabilities for continuous monitoring, linearity, and multilocation detection. Magnetostrictive materials, which deform in response to magnetic fields or exhibit magnetization variation when stressed, offer a promising solution through ultrasonic waveguide thermometers. This study prototyped a high-temperature and radiation-tolerant UT consisting of a solenoid and a Galfenol waveguide, and quantified its performance as a thermometer up to 300 °C. The impact of waveguide diameter, ambient temperature, and thermal treatment on UT performance was then thoroughly assessed. Galfenol waveguides with diameters of 0.5 mm, 0.8 mm, and 1.0 mm showed uniform temperature-dependent behavior with minimal hysteresis error when cycled between RT and 300 °C. The acoustic attenuation coefficient decreased with increasing wire diameter, likely due to the combined effects of eddy currents and magneto-mechanical energy conversion. Although thermal annealing at 900 °C for an hour in a nitrogen environment caused significant surface damage to the waveguides, it effectively relieved internal stress, thus minimizing the nonlinearity in the acoustic attenuation coefficient. 

Abstract Inflatable structures, promising for future deep space exploration missions, are vulnerable to damage from micrometeoroid and orbital debris impacts. Polyvinylidene fluoride-trifluoroethylene (PVDF-trFE) is a flexible, biocompatible, and chemical-resistant material capable of detecting impact forces due to its piezoelectric properties. This study used a state-of-the-art material extrusion system that has been validated for in-space manufacturing, to facilitate fast-prototyping of consistent and uniform PVDF-trFE films. By systematically investigating ink synthesis, printer settings, and post-processing conditions, this research established a comprehensive understanding of the process-structure-property relationship of printed PVDF-trFE. Consequently, this study consistently achieved the printing of PVDF-trFE films with a thickness of around 40µm, accompanied by an impressive piezoelectric coefficient of up to 25 pC N⁻¹. Additionally, an all-printed dynamic force sensor, featuring a sensitivity of 1.18 V N⁻¹, was produced by mix printing commercial electrically-conductive silver inks with the customized PVDF-trFE inks. This pioneering on-demand fabrication technique for PVDF-trFE films empowers future astronauts to design and manufacture piezoelectric sensors while in space, thereby significantly enhancing the affordability and sustainability of deep space exploration missions.