A 2MeV thermionic cathode test stand was established to meet the requirement of the large area thermionic cathode system.A 100ram in diameter type'B'thermionic dispenser cathode was developed.A 1000A emission ...A 2MeV thermionic cathode test stand was established to meet the requirement of the large area thermionic cathode system.A 100ram in diameter type'B'thermionic dispenser cathode was developed.A 1000A emission current was produced at the voltage of the diode about 1.8MV,the pulse width about 90ns(FWHM),and the cathode temperature about 1350℃.The emission current density is 12A/cm^2.The results indicate that a large area thermionic cathode which produces high quality and high current electron beams is visible.The results also indicate that the ability of cathode emission relies on the diode-vacuum and cathode-temperature.展开更多
As the performance of vacuum electron devices is essentially governed by the properties of their cathodes,developing efficient and durable thermionic cathode is necessary and highly desired to meet the boosting requir...As the performance of vacuum electron devices is essentially governed by the properties of their cathodes,developing efficient and durable thermionic cathode is necessary and highly desired to meet the boosting requirements of vacuum electron devices.This review summarized the progress made in the past decades with a detailed discussion on the occurred various thermionic cathodes and their features,and the understandings of the correlation between the emission properties and the composition,where structure and synthesis method are well illustrated.Furthermore,dispenser cathodes with novel structures and emission mechanism are highlighted to indicate the recent achievement in this area of research,and Sc-cathode is considered as a promising candidate for the next-generation vacuum electron devices due to the greatly improved efficiency.However,challenges still exist to meet the ever-growing demands of thermionic cathode with collaborative requirement of high performance,easy fabrication and inadequate reproducibility.展开更多
The microwave discharge cusped field thruster is a novel concept of electric micropropulsion device,which operatesμN level thrust in low mass flow rate conditions,making use of a coaxial transmission line resonator.W...The microwave discharge cusped field thruster is a novel concept of electric micropropulsion device,which operatesμN level thrust in low mass flow rate conditions,making use of a coaxial transmission line resonator.With its advantages of low thrust noise and high thrust resolution over a wide range of thrust,the thruster has emerged as a candidate thruster for the space-borne gravitational wave detection mission.The cathode effects commonly exist in many kinds of electric propulsion,and they are typically significant in micropropulsions.In order to find out the cathode position effects on a microwave discharge cusped field thruster,a thermionic cathode is mounted on a cross-slider for coupling.Under different cathode positions,the plume is analyzed by a Faraday probe and a retarding potential analyzer to analyze the performance and discharge characteristics.The results show that the magnetic mirror effect leads to significant degradation of anode current and an increase in low-energy ion ratio as the cathode moves away from the thruster exit.The electron conduction route also significantly impacts anode current efficiency,related to the cathode-exit distance and the thruster magnetic topology.展开更多
文摘A 2MeV thermionic cathode test stand was established to meet the requirement of the large area thermionic cathode system.A 100ram in diameter type'B'thermionic dispenser cathode was developed.A 1000A emission current was produced at the voltage of the diode about 1.8MV,the pulse width about 90ns(FWHM),and the cathode temperature about 1350℃.The emission current density is 12A/cm^2.The results indicate that a large area thermionic cathode which produces high quality and high current electron beams is visible.The results also indicate that the ability of cathode emission relies on the diode-vacuum and cathode-temperature.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.51534009)the Beijing Municipal High Level Innovative Team Building Program(Grant No.IDHT20170502).
文摘As the performance of vacuum electron devices is essentially governed by the properties of their cathodes,developing efficient and durable thermionic cathode is necessary and highly desired to meet the boosting requirements of vacuum electron devices.This review summarized the progress made in the past decades with a detailed discussion on the occurred various thermionic cathodes and their features,and the understandings of the correlation between the emission properties and the composition,where structure and synthesis method are well illustrated.Furthermore,dispenser cathodes with novel structures and emission mechanism are highlighted to indicate the recent achievement in this area of research,and Sc-cathode is considered as a promising candidate for the next-generation vacuum electron devices due to the greatly improved efficiency.However,challenges still exist to meet the ever-growing demands of thermionic cathode with collaborative requirement of high performance,easy fabrication and inadequate reproducibility.
基金supported by the National Key R&D Program of China(No.2020YFC2201000)National Natural Science Foundation of China(No.11927812)。
文摘The microwave discharge cusped field thruster is a novel concept of electric micropropulsion device,which operatesμN level thrust in low mass flow rate conditions,making use of a coaxial transmission line resonator.With its advantages of low thrust noise and high thrust resolution over a wide range of thrust,the thruster has emerged as a candidate thruster for the space-borne gravitational wave detection mission.The cathode effects commonly exist in many kinds of electric propulsion,and they are typically significant in micropropulsions.In order to find out the cathode position effects on a microwave discharge cusped field thruster,a thermionic cathode is mounted on a cross-slider for coupling.Under different cathode positions,the plume is analyzed by a Faraday probe and a retarding potential analyzer to analyze the performance and discharge characteristics.The results show that the magnetic mirror effect leads to significant degradation of anode current and an increase in low-energy ion ratio as the cathode moves away from the thruster exit.The electron conduction route also significantly impacts anode current efficiency,related to the cathode-exit distance and the thruster magnetic topology.
