Reliable steady-state magnetic diagnostics are a prerequisite for plasma control in long-pulse fusion devices like ITER and DEMO, where inductive sensors are limited by integrator drift. While antimony (Sb) Hall sensors offer the thermal resilience required for these harsh environments, previous designs have suffered from structural instability due to copper diffusion into the sensing layer at elevated temperatures. This paper reports on the development of a fourth-generation antimony Hall sensor incorporating a 500 nm tungsten–titanium (W–Ti) diffusion barrier. Accelerated aging tests confirm that the barrier effectively suppresses copper migration at temperatures exceeding 300 °C, preventing the degradation observed in earlier iterations. The sensors demonstrate constant sensitivity across a ±2.5 T magnetic field range and linear temperature dependence in a broad temperature range around 100 °C. These results validate the sensor’s suitability for the ITER outer vessel steady-state sensor system and establish a robust initial technological baseline for the development of such sensors for the high-radiation, high-temperature environment of DEMO.
Antimony Hall sensor testing at ITER and DEMO relevant temperatures