SWEATERS: a gas detector-based ENA sensor for space weather and plasma monitoring

The SWEATERS project introduces an innovative sensor for detecting Energetic Neutral Atoms (ENAs) to advance space weather monitoring and plasma environment diagnostics. For the first time, an ENA sensor employs MICROMEGAS detector technology (which was originally developed at CERN for High-Energy Physics) adapted for low-energy neutral particles in the 1–100 keV range. This cross-disciplinary approach applies state-of-the-art gaseous detection technology to space instrumentation, addressing requirements for miniaturization, mechanical robustness, and multi-parameter measurement capability. The SWEATERS sensor will provide compact, low-power operation with simultaneous measurement of ENA mass, energy, and arrival direction, enabling detailed characterization of dynamic plasma populations in solar and magnetospheric phenomena. The detector uses a nanometer-thick entrance window and operates with low-pressure gas mixtures (50–150 mbar) to minimize particle scattering while maintaining structural integrity in vacuum. MICROMEGAS technology delivers excellent gain stability and energy resolution under these conditions. Laboratory characterization using a bulk MICROMEGAS prototype has validated the concept through systematic measurements of gas gain, energy resolution, and signal response under varying electric field configurations, gas pressures, and compositions. Testing with X-ray sources and ion beams has advanced the system to Technology Readiness Level (TRL) 3–4. SWEATERS establishes a foundation for next-generation gas-based ENA imagers with applications in planetary exploration, heliophysics, and space weather science.