节流孔板位置对空心阴极特性的影响研究

Study on Influence of Orificed Plate Position onPerformance of Hollow Cathode

关键词:  节流孔板  空心阴极  宽放电电流范围

Key words:  Orificed plate  Hollow cathode  Wide discharge current range

摘要:

为满足全电推进系统的宽放电电流范围需求，开展了节流孔板内移研究。将传统结构空心阴极的一部分发射体转移到节流孔板下游，即节流孔板夹放在两段发射体之间。对比测试发现，新结构阴极的阳极电压大约降低4V，空心阴极的内压提升约50%，供气管外壁最大温差由原来的94℃下降到25℃，阳极电压振荡小于8V。进一步，利用光谱诊断系统，对阴极羽流区进行了研究。通过对羽流区等离子体固定位置进行全谱（400nm~1000nm）扫描，发现节流孔板内移之后，阴极羽流区新出现了波长为529nm和542nm的光线。利用Kura相机拍摄的羽流区二维等离子体分布图像显示，当放电电流为4A时，阴极羽流区的Xe和Xe⁺的密度低于传统结构空心阴极。宏观特性测试结果显示节流孔板内置式阴极可以在更宽的电流范围内维持点模式工作。可用于需要宽放电电流范围的全电推进系统以及需要低阴极供气流量、高比冲的小型电推进平台。

Abstract:

In order to meet the wide discharge current range demand of all-electric propulsion systems, a hollow cathode with the built-in orifice plate is investigated. Part of the emitter of the traditional hollow cathode is moved to the downstream side of the orificed plate. Namely, the orificed plate is set between two sections of emitters. Compared with the traditional hollow cathode, the discharge voltage of the newly designed cathode decreases about 4V, the inner gas pressure increases about 50%, the maximum temperature difference of the gas supply tube decreases from 94℃ to 25℃, and the anode voltage oscillation is less than 8V. Furthermore, the optical diagnostic systems are used to study the emission spectral at the cathode plume region. By using full-spectrum (400nm~1000nm) scanning at the fixed position of the plume region, it shows that light with wavelengths of 529nm and 542nm appears in the cathode plume region of the new structure cathode. The 2-D plasma image taken by the Kura camera shows the density of Xe and Xe⁺ in the plume region of the cathode are lower than the conventional cathode when the discharge current is 4A. The results show that this new hollow cathode can maintain the spot mode in a wider discharge current range. It can be used in all electric propulsion systems with wide discharge current range and small electric propulsion systems with low gas flow rate and high specific impulse.