Plume Control of a Cusped Field Thruster
The cusped field thruster uses several permanent ring magnets of alternating polarity to create a multistage cusp magnetic topology. It has demonstrated a long lifetime because of reduced plasma losses to the discharge channel surface. However, the high beam divergence problem has not been solved in this type of thruster. The purpose of this technical note is to describe a plume control method to reduce its plume angle. The results show that the magnetic field intensity in the plume region and the shape of the last separatrix have great influence on plume divergence.
Overview of Hall Electric Propulsion in China
Hall thruster is an attractive type of electric propulsion that is being developed to replace the chemical propulsion deployed in many tasks on satellites. The research on Hall thrusters in China has gradually progressed from basic theory to engineering applications, especially with the experience of on-orbit flight tests in low earth and geostationary equatorial orbits. This paper discusses the progress of research on Hall thrusters in China in recent years. This includes the beam focusing, scaling, high specific impulse, long lifetime, and effective magnetic field excitation techniques, as well as the stabilization technique of low-frequency oscillation, along with other types of Hall thrusters, such as cylindrical Hall, double-stage Hall, cusped field, nested-channel Hall, and anode layer Hall thrusters. In conclusion, this paper discusses the programs intended for the future focusing on the development of thrusters, their application prospects, and their use in space applications.
Investigation of the relative sensitivity of control of impulse X-ray television systems
Method of calculating the relative sensitivity for X-ray television systems based on X-ray screens, CCD cameras and impulse x-ray devices was proposed. To visualize the images formed by the pulsed X-ray radiation, an adjustable duration of accumulation on the CCD camera was used. The relative sensitivity of the control is determined by the intersection of dependences of the luminance and threshold contrast on the size of the defect. The comparison of calculated and experimental values of the relative sensitivity of control is made in this paper.