Like the hollow cathode,discharge instability also occurs during the operation of a plasma contactor.Voltage and current probes were employed to test the change of keeper voltage,keeper current,anode voltage,and anode...Like the hollow cathode,discharge instability also occurs during the operation of a plasma contactor.Voltage and current probes were employed to test the change of keeper voltage,keeper current,anode voltage,and anode current parameters with time under different working conditions.The anode current range corresponding to the discharge instability phenomenon is about 0.4 A to 1.2 A,and the emission characteristic curve in this area appears to bulge wherein the four parameters all produce different degrees of oscillation,the anode current oscillation being the greatest.Its waveform is considered to consist of a small-amplitude,high-frequency triangular wave and a large-amplitude,low-frequency sawtooth wave,and we have explained the shape of the wave.Each parameter shows hundreds of Hz in oscillation frequency and the phases of the four parameters appear to be regular.After fast Fourier transform processing,the frequency and amplitude of the main peak of the anode current oscillation tend to change with changes of the anode current,and there are differences in the trends under different keeper currents and xenon flows.展开更多
Hollow cathode,with the highest plasma density,current density,and temperature,becomes one of the most important components in the electro-thruster system.As the electric-propulsion thruster performance is directly re...Hollow cathode,with the highest plasma density,current density,and temperature,becomes one of the most important components in the electro-thruster system.As the electric-propulsion thruster performance is directly related to the ionization rate,reliability,and lifetime of the hollow cathode,this paper develops a global model to study the effects of discharge current,gas flow rate,and gas species on the discharge characteristics in the insert and orifice regions of the hollow cathode.The emitter wall temperatures of hollow cathodes predicted by the global model are compared with experimental results from NSTAR thruster neutralization cathodes,confirming the model's validity.The influence of hollow cathode emitter material and structure sizes on the plasma parameters in the internal regions was also evaluated.The simulation results show that there is an optimal matching relationship between the discharge current and gas flow rate to guarantee the maximum ionization rate.The optimal working region for the hollow cathode has been deter-mined under different energetic,regime and structural parameters.The global model established in this paper can quickly determine the key structure and operating parameters of hollow cathode at the design stage,and provide the theoretical basis for hollow cathode design and development.展开更多
基金financial support from National Natural Science Foundation of China(Nos.11402025,11475019,and 11702123)National Key Laboratory of Science and Technology on Vacuum Technology and Physics(No.ZWK1608)Advanced Space Propulsion Laboratory of BICE and Beijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology(No.Lab ASP-2018-03)。
文摘Like the hollow cathode,discharge instability also occurs during the operation of a plasma contactor.Voltage and current probes were employed to test the change of keeper voltage,keeper current,anode voltage,and anode current parameters with time under different working conditions.The anode current range corresponding to the discharge instability phenomenon is about 0.4 A to 1.2 A,and the emission characteristic curve in this area appears to bulge wherein the four parameters all produce different degrees of oscillation,the anode current oscillation being the greatest.Its waveform is considered to consist of a small-amplitude,high-frequency triangular wave and a large-amplitude,low-frequency sawtooth wave,and we have explained the shape of the wave.Each parameter shows hundreds of Hz in oscillation frequency and the phases of the four parameters appear to be regular.After fast Fourier transform processing,the frequency and amplitude of the main peak of the anode current oscillation tend to change with changes of the anode current,and there are differences in the trends under different keeper currents and xenon flows.
基金supported by the National Natural Science Foundation of China (Nos.U22B20120,NSFC52202460 and NSFC52177128)the National Key R&D Program of China (Nos.2020YFC2201100 and 2021YFC2202804,2022YFB3403504)+1 种基金the China Postdoctoral Science Foundation (Nos.2021M690392 and 2021TQ0036)the Advanced Space Propulsion Laboratory of BICE and Beijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology,China (No.LabASP-2021-04).
文摘Hollow cathode,with the highest plasma density,current density,and temperature,becomes one of the most important components in the electro-thruster system.As the electric-propulsion thruster performance is directly related to the ionization rate,reliability,and lifetime of the hollow cathode,this paper develops a global model to study the effects of discharge current,gas flow rate,and gas species on the discharge characteristics in the insert and orifice regions of the hollow cathode.The emitter wall temperatures of hollow cathodes predicted by the global model are compared with experimental results from NSTAR thruster neutralization cathodes,confirming the model's validity.The influence of hollow cathode emitter material and structure sizes on the plasma parameters in the internal regions was also evaluated.The simulation results show that there is an optimal matching relationship between the discharge current and gas flow rate to guarantee the maximum ionization rate.The optimal working region for the hollow cathode has been deter-mined under different energetic,regime and structural parameters.The global model established in this paper can quickly determine the key structure and operating parameters of hollow cathode at the design stage,and provide the theoretical basis for hollow cathode design and development.
