电推进空心阴极热子的寿命评估研究

Research on Life Assessment of Electric Propulsion Hollow Cathode Heater

关键词:  电推进  空心阴极  阴极热子  可靠性  寿命评估

Key words:  Electric propulsion  Hollow cathode  Cathode heater  Reliability  Life assessment

摘要:

为了评估阴极热子失效对阴极寿命的影响，在考虑空心阴极热子加热功率和蒸发速率的基础上，利用建模分析的方法研究了阴极热子阻值退化过程及热子初始半径对寿命的影响，分析了阴极热子寿命评估的误差传播特性和基于阻值变化的阴极热子寿命评估方法。结果表明阴极热子退化过程是一种典型的失稳过程；阴极热子寿命对初始半径的敏感度较高，热子半径每减少2μm，寿命减少约50%；热子初始半径误差在退化过程中会被剧烈放大，初始值的微小标准差经过这一发散过程后标准差从0.046增大到0.083，高于初始值近两倍，在空心阴极的加速寿命评估中恒流工作模式的稳定性较差。

Abstract:

In order to assess the effects of heater failure on lifetime of hollow cathode，on the basis of considering evaporation rate and heating power of the hollow cathode heater，the modeling analysis method was used to research resistance degradation processes of cathode heater and the influence of its initial radius on lifetime. The error propagation characteristics of the cathode heater life assessment and cathode heater life assessment method based on changes in resistance were analyzed. The results show that degradation process of cathode heater is a typical instability process，the life of cathode heater is more sensitive to initial radius，the radius of the heater is reduced each 2μm，the reduction of lifetime expectancy is by about 50%. Initial error of cathode heater radius will be severely enlarged in the degradation process，the small standard deviation of the initial value after the divergence process increases from 0.046 to 0.083，nearly twice higher than that of the initial value，and the stability of constant current mode in the accelerated life assessment of hollow cathode is lower.