微型阴极电弧推力器阴极斑点运动特性及等离子体射流加速机理研究

The micro cathode arc thrusters (μCAT) with light quality, small volume, and low power consume could meet the badly demand of the attitude and orbit controls of the micro- and nano- satellites. The on orbit verification has been conducted by America in 2015. The motion characteristics of the cathode spots and the acceleration processes of plasma jet, which play the important roles in the working performance, efficiency and reliability of the μCAT, involves quite a lot of fundamental scientific problems and it is of great need to investigate related basic theory and key technology. Therefore, in order to improve the working performance, efficiency and reliability of the micro cathode arc thrusters, this research proposal intends to investigate the motion characteristics of the cathode spots and the acceleration processes of plasma jet in the micro cathode arc thrusters ,in which a complicated condition with coexistence of coupled thermal field, flow field, and electromagnetic field. By combination of theoretical modeling, numerical simulation and experimental diagnostics, this proposal plans to study electrode erosion mechanism coupled with the motion characteristics of the cathode spots, the transport mechanism of metal vapor arc plasma and acceleration mechanism of the metal plasma jet under the condition with coexistence of coupled multi physics fields, and the comprehensive regulation methods by means of key control factors including discharge parameters, electrode structures, electrode materials as well as the applied magnetic field for the purpose of improving thruster performance. With current investigations, the applicants attempt to solve the main obstacle restricting the thruster performance, and meet the application requirements of the micro- and nanosatellites. It is also deeply expected that current work can promote the development of the motion characteristics of the cathode spots and the acceleration mechanism of plasma jet under the condition with coexistence of coupled multi physics fields.

质量轻、体积小、功耗低的微型阴极电弧推力器（μCAT）可满足微纳卫星对姿轨控制的迫切需求，2015年美国已开始其在轨验证工作。阴极斑点运动特性和等离子体射流加速过程对μCAT推力器的工作性能、效率和可靠性有重要影响，涉及到大量科学问题，有待尽快开展相应的基础理论与关键技术研究。以提高工作性能、效率和可靠性为目标，本项目拟开展μCAT推力器阴极斑点运动特性和等离子体射流加速机理的研究，针对真空电弧内部及羽流区热场、气流场、电磁场等多物理场耦合的特点，理论研究、数值仿真和实验测试相结合，分别从阴极斑点运动特性和烧蚀耦合作用机制、多物理场耦合下金属蒸汽电弧输运和金属等离子体射流加速机理以及关键控制条件协同下推力器工作性能的综合调控方法三个方面进行探索，尝试解决制约推力器性能的主要问题，满足微纳卫星应用需求，促进多物理场耦合下阴极斑点运动特性和等离子体射流加速机理的完善和发展。

微阴极电弧推力器（μCAT）在满足了微纳卫星对推进模块提出的重量、体积、功耗等严格约束下实现了高集成、高精度的高效能动力输出，可服务于我国微纳星群长期轨道维持、高精度编队飞行（多星高精度协同、精细姿轨控制）和寿命末期主动离轨等任务，将进一步提升我国微纳星群执行任务多样性、恶劣环境适应性等能力。.本项目以自研的μCAT推力器样机为研究对象，建立和完善了实验测量系统，并进行了μCAT推力器主要性能（推力、比冲等）和特征参数（电压、电流等）的测量，获得了较为系统的实验测量结果；实现了推力器低电压起弧，通过实验观测加深了对阴极斑点运动特性及等离子体射流加速机理的理解，明细了推力器阴极烧蚀特性及作用机理，考察了μCAT推力器工作性能影响因素；研究了推力器寿命过程中放电特性变化，获得了推力器延寿方法；通过基于PIC/MCC的数值模拟方法，对μCAT推力器内等离子体射流的加速过程和机理、外加电磁场的影响规律等进行了研究，获得了与实验较为一致的结果和规律；获得了推力器综合调控方法和策略；完成了μCAT推力器在轨验证，特别是国际上首次完成了μCAT推力器工作参数对元冲量控制的在轨测试及验证，使真空电弧类推力器推力调节范围扩大三倍。.本项目的基础研究和关键技术攻关涉及到的金属电极烧蚀控制、低电压可靠放电触发、脉冲等离子体输运等过程，是等离子体应用领域的普遍问题，相关研究成果对我国其他类型的电推进技术水平的提升，以及军用和民用的长寿命电器可靠性提升、等离子体应用等也具有重要的意义。