A Laser Quenching Fluorescence Diagnostic System for Measuring Edge Recycling Particle Velocity Distribution

The recycling of neutral particles in the edge region of fusion plasma is critical for fueling and sustaining the plasma. However, this process can lead to uncontrollable increases in neutral particle density, affecting plasma density and potentially causing discharge termination. To address this, understanding hydrogen isotope recycling into the edge plasma requires precise control and measurement of neutral particle density. Laser-induced fluorescence (LIF) is a powerful spectroscopic technique used for local velocity distribution measurements of neutral particles and ions. This study introduces a novel diagnostic technique, laser-induced quenching (LIQ) diagnostic, as an alternative to the conventional two-photon absorption laser-induced fluorescence (TALIF) diagnostic. The LIQ diagnostic aims to overcome limitations of TALIF, such as background line radiation interference and low collision cross-section, which impact signal-to-noise ratio. LIQ shows promise for assessing Edge Recycling Particle Velocity Distribution in fusion reactor edge regions, offering improved diagnostic capabilities and accuracy in plasma edge region control.