超声分子束束流辉光放电系统研制及应用

Development and Application of Supersonic Molecular Beam Glow Discharge System

  • 摘要: 超声分子束注入作为磁约束聚变装置中一种常用的加料及边界粒子控制技术,因其速度快、定向性优良等特点被广泛应用。为优化束流特性,一种用于测量束流特性分布的辉光放电系统被研制,并被应用于束流结构及参数的研究分析。实验结果表明,束流电离的过程可分辨条件下最快约为0.7 ms,系统配置的高速相机可捕获束流的清晰结构,该结构可准确用于束流寂静区长度及发散角度等关键信息测量。超声分子束束流纹影测量对比实验验证了直流辉光放电束流参数的一致性及可靠性。在此过程中,通过对束流形貌演化过程的研究,揭示了超声分子束的马赫盘形成机制,为其性能优化提供了物理和数据支撑。在氖气超声分子束放电实验中,扫描探针系统测得的束流响应给出了束流传播方向上的速度分布。马赫盘附近区域的速度分布结构特征与超声束流演化模型的预测相符,且通过速度分布测量获得的寂静区长度与纹影实验建立的定标关系呈现高度一致性,这为超声分子束的全剖面分布测量及其与等离子体相互作用的深入研究奠定了实验基础。

     

    Abstract: 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.

     

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