Numerical Simulation Study Of Coaxial Micro-Cathode Arc Thruster

At present,with the gradual miniaturization and functionalization of satellite technology,the development momentum of micro-nano satellites is gradually rapid.μ-CAT has the advantages like small size,high specific impulse,and modularity,which can fully meet the needs of micro-nano satellites.This paper conducts simulation research onμ-CAT thruster,analyzes the particle transport process and mechanism in the thruster,studies the factors that affect the particle trajectory and performance,and analyzes the factors affecting the thruster life through simulation,and provides methods to improve the thruster life.（1）Based on the plasma particle simulation method,a two-dimensional axisymmetric model was established,and the particle transport process and mechanism of the coaxial micro-cathode arc thruster were studied by using the COMSOL particle tracking model.The study found that the electrons would form a high-density electron band on the magnetic field lines of the applied magnetic field,and the ions would gather near this low-potential channel.Due to the large difference in the moving speeds of electrons and ions,charge separation will occur in the computational domain,resulting in a large potential gradient difference.In this regard,the influence of different external magnetic field coil configurations on the particle trajectory of the thruster is studied,and it is found that the movement of the electromagnetic coil position will cause the magnetic field lines passing through the discharge area to become flat or steep,thereby affecting the ion velocity and specific impulse..The results show that when the electromagnetic coil head is placed parallel to the thruster cathode end face,the electrons and ions can be better restrained,and the ion velocity and specific impulse can be effectively improved.At the same time,I also study the effects of different magnetic field strength and discharge current on the performance of thrusters.It was found that the stronger the applied magnetic field and the greater the discharge current applied between anode and cathode,the more conducive to the improvement of the thruster performance.（2）Assuming that the discharge is in a local thermodynamic equilibrium state,the plasma is used as a conductive fluid medium,and the "DC-coupled discharge" interface in the COMSOL simulation software is used to simulate the plasma generated during the pulsed arc discharge.By incorporating the cathode and anode into the computational domain,the fluid-structure interaction method is used to ensure the continuity of current and heat transfer across the electrodes.The thermal field simulation research of the microcathode arc thruster is carried out because the heating problem of the thruster under longterm operation will affect the materials of the components inside the thruster,resulting in work failure and affecting the life of the thruster.The results show that when the material of the thruster shell is changed from 304 to aluminum,the life of the thruster can be more than doubled.Therefore,using a shell material with a higher surface emissivity and an insulating base material with a higher temperature resistance can reduce the thermal equilibrium temperature under a specific power and thus effectively increase the service life of the μ-CAT thruster.（3）According to the relevant theory,a coaxial μ-CAT thruster was designed and processed,and a vacuum experiment platform of the thruster was built.In the experiment,the discharge characteristics of the PPU were tested,the ignition discharge of the thruster was observed,the color of the plasma plume was observed under different vacuum degrees,and the ablation of the cathode was observed after the discharge of the μ-CAT thruster.Analyze the phenomena in the experiment.