Research On Static-State Arc Plasma Ionizations And Arc Characteristics For Aerospace Relays

With the fast development of aerospace technology, manned space flight technology of our country becomes mature day by day and deep exploration becomes an important developing direction. Aerospace relay is one of the most accessories in various deep exploring aerocraft. So its working life and reliability do great influence to the aerocraft. Arc will happen when the relay contacts break or close, which can make the contact working condition bad and influence the working life and reliability of aerospace relay badly. Therefore, it is very important to do some research on the arc characteristic of aerospace relay for improving its working life and reliability.Arc phenomenon is a traditional problem. Researchers in our country and abroad have done much work on it. However, most of their work is from macroscopic point, while few are from microscopic point. The microscopic model of arc plasma can do great help for people to know the inner physic process of arc deeply and be helpful to the research on the macroscopic process of arc plasma. Nevertheless, the research on this point has been scattered for a long period. This paper aims at the arc phenomenon of aerospace relay and does research on its theory model and experiment. Firstly, it sums up several main microscopic models on plasma, introduces their theory constructions, states the model change at whole thermodynamic equilibrium (WTE) and local thermodynamic equilibrium (LTE), compares various models simply and recommends Eindhoven model as a suitable model in engineering calculation.Secondly, the paper builds a microscopic model of aerospace relay, which based on Dalton's law, mass action law, charge neutral law and stoichiometric condition. It then gets non linear equations about number densities of various particles, combines the value of temperature and resolves them at several certain phenomena at two arc states WTE and LTE:â‘ pure nitrogen;â‘¡nitrogen with little metal vapor;â‘¢nitrogen with little metal oxygen;â‘£nitrogen with little metal water vapor. Then it discovers some influence on arc by impurity gases and does basic work for calculating other transport parameters of arc plasma future. In order to check the microscopic model, the paper does arc spectrum experiment, analyses arc spectrums of aerospace relay at aforementioned phenomena. This spectrum experiment and the theory research are supplements for each other, which practically improves the existance of each particle considered by microscopic model and reflects the existance of some particles never considered by the model. Based on the experiment results, it can do some amending work to the theory model.To research on the macroscopic parameters of arc burning, the paper designs a series of experiment. As the whole burning process of arc reflects the actual arc physical process, it records the process by high-speed photography. Based on the digital image processing on the photos, it gains some of the arc macroscopic parameters such as root radius, column radius, length, burning time, and so on. As the break capability of aerospace relay contact will be different at different load, the paper studys on the arc shape change while changing the load. And it draws some conclusions on the arc burning. What's more, it does some initial work on the mechanical action of contacts and gets the curve of the break speed changing with time.