Development and Application of Supersonic Molecular Beam Glow Discharge System

As a widely utilized fueling and boundary particle control technique in magnetic confinement fusion devices, supersonic molecular beam injection (SMBI) is extensively adopted due to its rapid delivery speed and excellent directionality. To optimize beam characteristics, a glow discharge system for measuring beam property distributions was developed. Based on the glow discharge principle, this system achieves collaborative operation with the SMBI offline testing platform through meticulous design of its structure and key components, and was applied to investigate beam configuration and parameters. Experimental results demonstrate that the beam ionization process occurs instantaneously. The high-speed camera integrated into the system captures well-defined beam structures, enabling precise measurement of critical parameters such as silent zone length and divergence angle. Comparative schlieren measurements of supersonic molecular beams validate the consistency and reliability of DC glow discharge beam parameters, effectively addressing the technical limitation of severe signal attenuation in low-density regions encountered by conventional optical diagnostics. During this process, the dynamic evolution of beam morphology reveals the Mach disk formation in supersonic molecular beams, characterized by its expansion from the nozzle exit followed by stabilization, thereby establishing a robust physical and empirical foundation for optimizing beam performance. The system exhibits a temporal resolution of ＜1 ms (0.7 ms measured), while the transient expansion phase of beam morphology culminating in hydrodynamic stabilization is completed within approximately 1 ms, demonstrating sufficient synchronization capability for capturing supersonic beam evolution dynamics. In neon-based supersonic molecular beam discharge experiments, an electrostatic probe displacement measurement system was established, which successfully derived axial velocity distributions from beam response measurements. The velocity profile characteristics near the Mach disk region align with predictions from supersonic beam evolution models, while the silence zone length obtained from velocity distribution measurements exhibits strong consistency with schlieren-based calibration relationships. These findings establish an experimental foundation for comprehensive profile measurements of supersonic molecular beams and in-depth investigations of beam-plasma interactions.