| The propulsion system is used to provide impetus for motion and control of spacecraft, which can accomplish many functions, such as orbit raising, repositioning, maneuvering, and drag compensation of large satellites and space stations. At present, electric propulsion system has been widely applied in space fight missions and ascendant performance of electric propulsion makes it a substitution of traditional chemical propulsion system gradually. Arcjet is one of the highlight of electric propulsion investigation and application because of its high thrust density, high ratio of thrust and power, preferable specific impulse, better system successiveness and reliability. With the development of space technology and the demand of aerospace task, it is important significance to investigate the Arcjet system.A Langmuir probe diagnostic system for Arcjet plume is established first in China, in which Langmuir probe is employed to obtain the electron temperature of the Arcjet plume with argon propellant. The experiment result shows that the electronic temperature is much higher than excitation temperature in the axis of the Arcjet plume, and the difference of the two temperatures in the edge of the plume is not too much. So the plume is in higher non-equilibrium state in the axis than in the edge of the plume. The difference and its mechanism are analyzed through comparison of experiment data, and the influence of thermal non-equilibrium state on the measurement results is also discussed.An Arcjet with water propellant has been experiment studied, and related problem of the application of water propellant is studied. In a typical working condition for water propellant with current of 8A and flow rate of 15mg/s, the average arc voltage is 80.5V, the average specific impulse is 650s and the highest specific impulse is 840s, and the efficiency is about 55%~60%. The specific impulse and efficiency is higher than argon propellant, and is also higher than N2H4 propellant reported in documentations. |
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