空心阴极微推力器研究进展

空心阴极微推力器是一种通过空心阴极放电产生高密度的等离子体,并将其喷出产生相应推力的电推力器,具有体积小、结构简单、研制难度小、成本低的优点,非常适合作为微小卫星的电推进系统。概述了空心阴极微推力器的系统组成和工作原理,介绍了国内外空心阴极微推力器的研究进展和发展现状,分析了不同结构的空心阴极微推力器的性能参数和特点,并对其关键技术及发展趋势进行了初步讨论。     

用于汞离子推力器的中和器空心阴极的实验研究

一、中和器空心阴极在推力器中的工作电子轰击式汞离子推力器组成部分、启动过程及正常运行,在文献[1]中,结合示意图1和图2作了简叙。汞离子推力器用中和器,如图1所示。由汽化器(5)绝缘器(6)和空心阴极(7)三部分组成。空心阴极为一气体放电电子源,当阴极加热到点火温度后。触持极(8)加上点火电压,阴极一触持极间首先着火放电。进而,放电扩展至汞离子束I_B。中和器阴极向离子束中发射与离子流等量电荷的电子流I_N,使推力器系统呈电中性。维持推力器稳定工作。     

离子推力器空心阴极点火可靠性评价研究

空心阴极作为离子推力器放电室等离子体电离源初电子和束流中和电子的电子源,其点火可靠性直接影响到推力器的工作可靠性。以20 cm离子推力器在轨工作剖面为例,对空心阴极预期寿命下的可靠度进行了评价。采用小样本的可靠性试验与可靠性评价理论结合的方法,得到了LHC-5空心阴极点火6 000次时在置信区间0.90和0.95的点火可靠性好于0.98。结果证明LHC-5空心阴极可靠性满足空间应用要求。研究成果对空心阴极可靠性增长设计和电推进产品可靠性评价方法研究具有积极意义。     

用于电子轰击式汞离子推力器空心阴极的实验研究

本文叙述了空心阴极在电子轰击式汞离子推力器中的功能、推力器对空心阴极的要求。给出了阴极材料、结构、工艺及某些实验结果:即空心阴极的真空发射性能;阴极的放电形式及其伏安特性;阴极点火电压与阴极温度及通过阴极汞流率的关系,稳定放电时离子轰击阴极的加热特性。     

石墨触持极空心阴极性能实验研究

空心阴极触持极溅射腐蚀会导致离子推力器性能退化甚至失效,为确保离子推力器长期工作性能稳定性,触持极材料应选用溅射腐蚀速率尽可能低的材料。开展不同触持极结构对空心阴极放电性能的影响研究。最后,进行了1 000 h短期地面寿命实验。实验结果表明,石墨触持极空心阴极放电性能稳定,长期工作触持极表面的溅射腐蚀不明显,能够有效避免空心阴极长时间工作后因触持极溅射腐蚀导致的性能退化。     

LaB6空心阴极发射体失效的拓展寿命模型及可靠性定量评估北大核心CSCD

空心阴极的寿命是制约离子推力器寿命及可靠性的关键因素之一,而发射体殆尽失效又是制约空心阴极寿命及可靠性的关键因素。在前面工作中,已建立了LaB6空心阴极工作在额定发射电流下时发射体的损耗过程及工作寿命预测模型,文章在此寿命预测模型的基础上提出了一种发射体寿命扩展模型,即发射体进一步消耗发射体下游顶端高温区域,利用扩展模型重新计算了发射体耗尽失效模式下空心阴极的寿命,并用威布尔统计规律及分析方法定量分析了空心阴极的可靠性,较基本模型而言,扩展模型中空心阴极的寿命及可靠性均得到明显提升。并且发射体温度分布对发射体寿命及可靠性有重要影响。     

阴极挡板对30cm氙离子推力器性能影响的研究

束流分布是表征离子推力器性能的关键技术指标,直接影响到离子推力器的工作稳定性和可靠性。针对引出束流分布不均匀导致30 cm氙离子推力器离子光学系统打火保护的问题,开展了阴极挡板性能试验,研究分析了阴极挡板对离子光学系统引出束流的影响作用关系,以及设置阴极挡板前后和设置不同规格阴极挡板时推力器放电室性能变化规律。试验表明:设置阴极挡板可有效提高离子光学系统引出束流分布的均匀性,进而改善推力器的连续工作稳定性;同时,设置阴极挡板后,推力器在高功率工作模式下的放电室阳极电压、放电损耗与未设置阴极挡板相比有明显增大,且放电室阳极电压、放电损耗随阴极挡板直径的增大而增大。研究为提高30 cm氙离子推力器工作稳定性提供技术指导。     

离子推力器束流下降原因分析

离子推力器的推力与其引出的束流成正比,束流的大小直接确定了推力.离子推力器在点火启动后,在工作条件不变的条件下,其引出束流随工作时间而下降.为找出束流下降的原因,以离子推力器为研究对象,通过分析引起离子推力器束流下降的各种因素,并对这些因素进行分析与验证.经过对因素的分析定位,找出引起束流下降的主要原因.分析与验证表明：影响离子推力器束流下降的决定因素为栅极组件固有特性、磁场固有特性和阴极固有特性,其中阴极固有特性是导致束流下降的主要原因.     

离子发动机空心阴极寿命预测

为验证空心阴极的寿命,本文根据空心阴极LaB6发射体的损耗特点,采用数学建模方法对空心阴极的寿命进行了预测.预测结果表明兰州物理研究所研制的空心阴极工作在额定状态下(发射电流5.00 A),其寿命可达到40000 h以上.3500 h寿命试验后空心阴极解剖分析结果初步验证了预测模型的正确性.     

离子发动机空心阴极失效形式分析

空心阴极是离子发动机关键部件,研究其失效形式,对提高离子发动机的可靠性有重要意义.介绍了离子发动机空心阴极的工作原理,分析离子发动机空心阴极的主要失效形式,并根据分析结果,提出了一系列提高离子发动机空心阴极可靠性的途径.     

Numerical prediction of wall erosion on a Hall thruster

Hall thrusters are promising space propulsion options for spacecraft. Current major interest in Hall thrusters is their life time evaluation for long time operation. Sputtering erosion of the insulation wall determines the life time of the thrusters. In this study, we present two-dimensional Hybrid-PIC modeling of Hall thrusters, which predicts the wall erosion effect. The principle challenges of our modeling is (1) solving both the plasma generation and acceleration in the channel and the exhaust plume in the near field of the exit and (2) predicting the channel erosion by ion sputtering with deforming the calculation grid. As a result, it was shown that the modeling simulated successive operations and wall erosions by ion sputtering during 2000 h operation of a Hall thruster.     

Elektrische Antriebe für die Raumfahrt

Electric Propulsion for Space Flight This article describes electric rocket motors for satellites, probes and manned spacecraft based on principles used for material processing, too. The need for high exhaust velocities is explained and the limitations of conventional chemical thrusters are pointed out. Two important electric propulsion technologies, arcjet thrusters and gridded ion thrusters, together with their applications are described. Both types are currently successfully operated in space. Finally, a hybrid engine using an arcjet thruster and propellant heating by radiofrequency power is introduced. This concept is a potential solution for the propulsion demands of a future piloted mission to Mars.     

Model of an ion flow and a method for calculating the erosion of discharge-chamber walls in a stationary plasma thruster

Technical Physics Letters - Morozov’s stationary plasma thrusters (SPTs) are used effectively in motion-control systems of Russian and foreign spacecraft, and the field of their application...     

The Possibility of the Ionization and Acceleration Layer Shifting outside the Magnetic Poles Plane in a Morozov Stationary Plasma Thruster

Technical Physics Letters - Requirements for stationary Morozov plasma thrusters are increasing due to the expansion of their use. Therefore, attempts are made to improve the organization of...     

Effect of solute mixing in the liquid propellant of a pulsed plasma thruster

Sodium chloride or ammonia was dissolved in the water propellant of pulsed plasma thrusters to improve the performance. Pulsed plasma thrusters using liquid propellant utilize water as attractive alternative instead of Teflon. Water propellant enables in controlling propellant mass flow and leads to high specific impulse. However, liquid propellant pulsed plasma thrusters have larger plasma resistance and lower thrust power ratio than the common Teflon propellant thruster. Here, sodium chloride and ammonia solution of water were examined to decrease that plasma resistance. As a result, emission lines attributed from the solute were observed using sodium chloride aqueous solution propellant, and a 5% reduction of the plasma resistance was shown, and the thrust to power was increased. However, ammonia aqueous solution decreased the thruster performance.     

氙离子推力器放电室等离子体离子产生成本的测量与分析

离子推力器放电室等离子体离子的产生成本是影响推力器性能优劣的重要参数之一.从理论上分析了影响等离子体产生离子的能量消耗成本的基本因素,同时测量了不同工作条件下离子推力器的等离子体离子能量消耗成本值.试验结果与理论分析取得了良好的一致性.通过对试验结果的分析,得到离子推力器放电室等离子体离子消耗成本的最佳选取点.     

中高功率离子推力器的性能参数分析研究

此次系统调研在已有高功率离子推力器研制情况的基础上,对中高功率离子推力器的主要性能参数进行了分析研究,得到了离子推力器性能随功率变化的经验关系,并应用这些关系分析预测了中高功率离子推力器的性能极限,得出了基于现有技术的离子推力器难以满足未来高功率电推进使命需求的分析结论。     

Energy balance in a stationary plasma thruster

The wide use of stationary plasma thrusters (SPTs) in space vehicles poses the natural task of increasing their efficiency, which is among the most important parameters to be optimized. For the maximum expediency of research in this direction, it is important to know the distribution of energy supplied to the thruster. For this purpose, we have measured the temperatures of various elements in the construction of a typical SPT and studied heat fluxes that determine the energy balance of the system.     

Performance characteristics of very low power cylindrical Hall thrusters for the nano-satellite “PROITERES-3”

Development of Hall thrusters for nano, small and low power satellites below 100 W is expected. In lowering Hall thruster power, the cylindrical type Hall thruster is more advantage than conventional coaxial-type Hall thrusters. In this study, a very low power cylindrical Hall thruster for nano-satellite “PROITERES-3” under development in Osaka Institute of Technology was designed, and the thruster performance was measured. As a result, a stable operation was achieved even with 10 W. The anode specific impulse and the anode thrust efficiency were 1570 s and 18.1%, respectively, with 66 W. Also, the discharge current oscillation was lower compared with that of SPT-type Hall thruster.     

Vacuum Challenges for Ion Thruster Testing

Electrical propulsion is the keyword for nowadays movement of space vehicles. Ionized particles, usually xenon ions, are accelerated by thrusters in an electric field. State-of-the-art xenon thrusters emit a gas flow of 0.1 to 10 mg/sec. In order to maintain a high vacuum pressure at this flow in thruster test chambers, a large pumping speed is required, often in the range of 10'000 to 100'000 l/s for xenon. The advantage of a large ion mass for the propulsion system is a major challenge for vacuum pumps. Leybold has developed an optimized and simple cryogenic solution for Xe pumping. Strong single-stage Gifford-McMahon type cold heads carry metal discs which condense the Xe gas with a pumping speed at the edge of the theoretical limit. In this work, we will present the whole vacuum system for a thruster testing facility.