A study of grid failure mode drivers and methods for accelerated life testing of a 30cm diameter ion thruster

In view of the high cost caused by the 1:1 lifetime verification test of ion thrusters, the lifetime acceleration test should be considered. This work uses the PIC-MCC(Particle-in-Cell MonteCarlo Collision) method to analyze the five failure factors that lead to the failure of the accelerator grid of a 30 cm diameter ion thruster under the working mode of 5 k W. Meanwhile,the acceleration stress levels corresponding to different failure factors are obtained. The results show that background pres...     

小行星探测及采样返回任务电推进系统方案设计

离子电推进具有高比冲、长寿命、多工作点可调的优势,能够很好的适用于小行星探测器巡航阶段主推进任务,可以大幅提升探测器的有效载荷比和空间进入能力。通过调研国外电推进在深空探测任务中的应用情况,结合我国小行星探测任务规划,在充分借鉴国外成功经验和全面继承我国电推进研制经验的基础上,依据任务需求,对可选用的多种电推进系统开展了对比分析,可以看出离子电推进系统具有显著优势。在此基础上,以既定任务为例,设计了不同配置的小行星探测离子电推进系统方案,对比分析了各方案的优劣势,最后对小行星探测离子电推进的关键技术进行了分析讨论。研究结果将为我国小行星探测任务提供参考。     

汽轮机组轴振值增高的原因分析与在线动平衡方法应用探究

某石化公司汽轮机组大修后进行机组联试。联试期间转速升至10 700 r/min时,汽轮机联轴器侧轴振测点VE3349A振动值为39μm,低压缸驱动侧轴振测点VE3244振动值为43μm,2处轴振值比检修前有所增高。根据振动波形频谱图、轴心轨迹图、Bode图进行分析,现场进行动平衡调整,取得明显效果,轴振值得以大幅减小,消除了故障隐患。     

兴能电厂600MW超临界锅炉运行与调整

叙述了山西兴能电厂二期600 MW超临界直流锅炉的运行调整方法,指出,锅炉汽温变化是运行调整的主要因素,提出了针对影响燃烧稳定性的调整措施。     

Plasma characteristics in the discharge region of a 20A emission current hollow cathode

Numerical calculation and fluid simulation methods were used to obtain the plasma characteristics in the discharge region of the LIPS-300 ion thruster’s 20 A emission current hollow cathode and to verify the structural design of the emitter.The results of the two methods indicated that the highest plasma density and electron temperature,which improved significantly in the orifice region,were located in the discharge region of the hollow cathode.The magnitude of plasma density was about 10~(21)m~(-3)in the emitter and orifice regions,as obtained by numerical calculations,but decreased exponentially in the plume region with the distance from the orifice exit.Meanwhile,compared to the emitter region,the electron temperature and current improved by about 36%in the orifice region.The hollow cathode performance test results were in good agreement with the numerical calculation results,which proved that that the structural design of the emitter and the orifice met the requirements of a 20 A emission current.The numerical calculation method can be used to estimate plasma characteristics in the preliminary design stage of hollow cathodes.     

A study of the influence of different grid structures on plasma characteristics in the discharge chamber of an ion thruster

The grid structure has significant effects on the discharge characteristics of an ion thruster.The discharge performances of a 30 cm diameter ion thruster with flat,convex and concave grids are studied.The analysis results show that the discharge chamber with a convex grid has a larger’magnetic-field free area’ than the others,and the parallelism of the magnetic-field isopotential lines and anode is generally the same in the three models.Plasma densities of the three structures at the grid outle...