System Design And Performance Test Of Micro-Cathode Arc Thruster

With the development of micro-nano satellites,the micro-propulsion system has been paid more attention to.The Micro-Cathode Arc Thruster(μ-CAT)is a new type of electric propulsion device based on vacuum arc discharge excitation and accelerating plasma injection to generate thrust.The thruster has many advantages such as small size,low power consumption and light weight.The thruster has a broad application prospects in the field of micro-nano satellites.In this paper,the working principle of the μ-CAT is analyzed in detail.The thrust system consists of three parts: the thruster head,the power process Unit(PPU)and the magnetic system.Its working principle is as follows: The thruster relies on the PPU to transfer DC input voltage into pulsed high voltage.The thruster head uses the pulsed high voltage to excite arc which generates the plasma.Then the plasma is accelerated by the magnetic filed to eject from the thruster to obtain the thrust force.Furthermore,the subsystems of the μ-CAT system are designed and developed under the guidance of relevant theories.The overall weight of the thruster does not exceed 300 g,and the size of it is not more than 1U(10cm × 10 cm × 10cm).In this paper,a set of μ-CAT ground experiment system is built on the platform of high vacuum electric propulsion,including the high vacuum platform,the discharge parameter measuring device and the plume probe.To carry out the test under high vacuum and record the discharge characteristic curve through the oscilloscope.The parameters of thruster such as discharge current,discharge voltage,discharge time and so on can be obtained.Using the self-made probe to detect the plume produced by the thruster,the velocity of the plasma is obtained,then the specific impulse is gained.The distribution of the plume ion current is measured by using a number of Faraday probes.Through the measurement the plume distribution can be achieved.In this paper,the experimental characteristics and test results of the thruster are summarized,and the performance characteristics and related parameters of the micro-arc cathode thruster are concluded.According to the plume observation results of the thruster,the coaxial type electrode structure is favorable for the discharge of the plasma.The cathodic spots on the cathode surface after the experiment show that the discharge cathode is ablated by the arc during the operation of the thruster.The cathode,not only as a discharge electrode,but also as a propellant is promoted by spring.So the thruster does not need to carry the propellant storage system,this feature is suitable for micro-nano-satellites.After the experimental measurement,the specific impulse of the thruster can reach several ten thousand meter per second.And with the increase of the magnetic induction strength,it effectively boosts the specific impulse.The plume flows into a divergent distribution,and the plume flows in the absence of an external magnetic field.Increasing the external magnetic field can play the role of plume flow,which can effectively avoid the pollution caused by plume backflow to the thruster.