*Sandia National Laboratories developed a laser-based crystal sensor that accurately measures intense magnetic fields in radiation-heavy fusion environments, improving diagnostics and reactor reliability.*
A rare earth garnet used by Sandia National Laboratories researchers to measure intense magnetic fields, such as those needed for fusion research and high-energy physics experiments.

Researchers at Sandia National Laboratories have developed a compact laser-based crystal sensor capable of accurately measuring extremely intense magnetic fields in harsh environments, offering a promising current diagnostic tool for future fusion power plants. About the size of a pencil eraser, the device is designed to withstand radiation, electromagnetic interference and fusion plasma conditions that often overwhelm conventional magnetic field sensors.

The sensor uses a rare-earth garnet crystal together with a small laser, optical filters and a light detector. As laser light passes through the crystal, its polarization changes in response to the surrounding magnetic field.



By measuring these optical changes, the system can determine magnetic field strength with high precision. Researchers used crystals made from terbium scandium aluminum garnet (TSAG) and terbium gallium garnet (TGG), whose optical properties respond strongly to electromagnetic forces.

Development began in 2021 to improve magnetic field measurements inside Sandia’s Z Machine, the world’s most powerful laboratory radiation source. The technology was subsequently tested at Sandia’s High-Energy Radiation Megavolt Electron Source III (HERMES III) and the Short Pulse High Intensity Nanosecond X-Radiator (SPHINX), where it matched the performance of conventional sensors while delivering more consistent measurements under extreme conditions.

Unlike conventional metallic probes, the crystal-based sensor requires less frequent calibration and maintenance and is electrically insulating, preventing failures caused by radiati

📌 Tiny crystal sensor improves magnetic field measurements inside fusion reactors (Delhi)
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