等离子体窗密封性能实验研究

等离子体窗具有高真空密封性和良好的束流通过性，在电子束焊接、加速器等领域有很大的应用前景. 针对传统等离子体窗应用孔径小的问题，本文在优化的三阴极源基础上研究了通道直径为7 mm和8 mm等离子体窗的密封特性，以及Ar、He、H2三种等离子窗压降系数随输入电流和气流量的变化关系. 结果显示，在输入电流120~210 A、气流量1000~5000 sccm范围内，Ar等离子体窗的压降系数随输入电流、气流量的增加呈先上升后下降的变化趋势，He、H2等离子体窗的压降系数随输入电流的增加逐渐上升，但随着气流量的增加，He等离子体窗的压降系数先上升后下降，H2等离子体窗的压降系数逐渐下降. 本实验获得的等离子体窗最大压降系数为2550，可隔绝的最大高压为1 atm，与已报道文献相比具备较好的竞争优势，展现了良好的密封性，在未来加速器等领域有很大的应用潜力.

Experimental study of plasma window sealing performance

Plasma windows with a high vacuum tightness and a good beam throughput have promising applications in electron beam welding, accelerators and so on. This paper, aiming at the small-size problems of traditional plasma window apertures, presents the sealing characteristics of the plasma windows with channel diameters of 7 mm and 8 mm on the basis of the optimized three cathode sources. The relationship between the pressure drop coefficient(PDC) of Ar, He and H2 and such experimental parameters as the input current and gas flow rate is studied, respectively. The input current was ranged from 120 to 210 A and the gas flow rate was done from 1000 to 5000 sccm. The results show that the PDC of the Ar plasma window firstly increases and then decreases with the increases of both the input current and gas flow rate. Differently, the PDC of the He and H2 plasma windows gradually increases with the increase of the input current,and with the increase of gas flow rate, the PDC of the He plasma window firstly increases and then decreases and the PDC of the H2 plasma window gradually decreases. The maximum PDC of the plasma windows obtained in this work is 2550, and the isolatable maximum high pressure is 1 atm. Compared with the reported literatures, these data mean that the developed plasma windows have a good competitive advantage and shows a good sealing performance for potential applications in fields of future accelerators.