The vacuum electronic device is the key components widely used in the fields of radar,navigation,electronic warfare and so on.Multi-brazing process is adopted in the manufacturing,and the leakage is easy to happen at ...The vacuum electronic device is the key components widely used in the fields of radar,navigation,electronic warfare and so on.Multi-brazing process is adopted in the manufacturing,and the leakage is easy to happen at many parts,such as brazed seams and base materials of tube shell,leading breakage of the devices.But now the brazing filler metal used in the stockage of vacuum electronic devices is very seldom.For the safe of vacuum electronic devices,stockage temperature must be lower than the brazing temperature.Gallium is liquid at room temperature,and has a lower vapor pressure.The Ga-based alloy can diffuse with the high melting point metal,and then form heat-resistance and a good sealing performance of solid-state alloys.In this study three kinds of Ga-based alloys used for the stockage were developed.The diffusion brazing for the stockage on three materials with defect,such as OFHC,kovar and Ag-Cu brazed seams was carried out.The influence factors such as parent materials,brazing filler metal and brazing temperature on the stockage quality were discussed.The results indicated that parent materials,brazing filler metals and brazing temperature had obvious influences on stockage.For OFHC and Ag-Cu filler with defects,the stockage effects were better than kovar.The effect of Ga-In-Cu alloy was the best because the compact diffusion layer was formed between the stockage brazing materials and base materials.As the brazing temperature went up,the diffusion layer formed between stockage material and OFHC,kovar became obviously thicker,the stockage effect got better.For Ag-Cu brazing seams,the stockage effect was satisfactory at 500℃,erosion will happen at the higher temperature.展开更多
Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, t...Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, the inherent velocity spread of the beam, which is difficult to measure in experiment, has a great influence on the operating frequency and efficiency of the vacuum electronic device. In this paper, the velocity distribution characteristics of the electron beam produced by a single-gap hollow cathode electron gun are numerically studied and a three-dimensional kinetic plasma simulation model of a single-gap hollow cathode electron gun is built by using particle in cell and Monte Carlo collision methods in Vorpal. Based on the simulation model, the time-dependent evolution of the plasma formation inside the hollow cathode and electron beam generation process are observed. It is demonstrated that the pseudospark-sourced electron beam has a relatively large velocity spread. The time-dependent velocity distribution of the beam is analyzed, and the dependence of the beam velocity distribution under various operating conditions such as anode–cathode potential difference, gas pressure, and cathode aperture size are also studied.展开更多
1.Introduction:High power microwave technology background and critical applications High power microwave(HPM)is defined as electromagnetic radia-tion exceeding 1 GW peak power or 1 MW average power within the frequenc...1.Introduction:High power microwave technology background and critical applications High power microwave(HPM)is defined as electromagnetic radia-tion exceeding 1 GW peak power or 1 MW average power within the frequency range of 300 MHz to 300 GHz.This perspective focuses on vacuum electronic device-based HPM sources,which rely on controlled magnetic fields for beam confinement and wave-beam interactions.The fundamental operating principle involves the conversion of kinetic energy from high-energy electron beams into electromagnetic energy through beam-wave interactions.展开更多
基金National Nature Science Foundation of China(51033026)
文摘The vacuum electronic device is the key components widely used in the fields of radar,navigation,electronic warfare and so on.Multi-brazing process is adopted in the manufacturing,and the leakage is easy to happen at many parts,such as brazed seams and base materials of tube shell,leading breakage of the devices.But now the brazing filler metal used in the stockage of vacuum electronic devices is very seldom.For the safe of vacuum electronic devices,stockage temperature must be lower than the brazing temperature.Gallium is liquid at room temperature,and has a lower vapor pressure.The Ga-based alloy can diffuse with the high melting point metal,and then form heat-resistance and a good sealing performance of solid-state alloys.In this study three kinds of Ga-based alloys used for the stockage were developed.The diffusion brazing for the stockage on three materials with defect,such as OFHC,kovar and Ag-Cu brazed seams was carried out.The influence factors such as parent materials,brazing filler metal and brazing temperature on the stockage quality were discussed.The results indicated that parent materials,brazing filler metals and brazing temperature had obvious influences on stockage.For OFHC and Ag-Cu filler with defects,the stockage effects were better than kovar.The effect of Ga-In-Cu alloy was the best because the compact diffusion layer was formed between the stockage brazing materials and base materials.As the brazing temperature went up,the diffusion layer formed between stockage material and OFHC,kovar became obviously thicker,the stockage effect got better.For Ag-Cu brazing seams,the stockage effect was satisfactory at 500℃,erosion will happen at the higher temperature.
基金Project supported by the Sichuan Science and Technology Program, China (Grant No. 2019YJ0188)the National Natural Science Foundation of China (Grant Nos. 61671116 and 11905026).
文摘Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, the inherent velocity spread of the beam, which is difficult to measure in experiment, has a great influence on the operating frequency and efficiency of the vacuum electronic device. In this paper, the velocity distribution characteristics of the electron beam produced by a single-gap hollow cathode electron gun are numerically studied and a three-dimensional kinetic plasma simulation model of a single-gap hollow cathode electron gun is built by using particle in cell and Monte Carlo collision methods in Vorpal. Based on the simulation model, the time-dependent evolution of the plasma formation inside the hollow cathode and electron beam generation process are observed. It is demonstrated that the pseudospark-sourced electron beam has a relatively large velocity spread. The time-dependent velocity distribution of the beam is analyzed, and the dependence of the beam velocity distribution under various operating conditions such as anode–cathode potential difference, gas pressure, and cathode aperture size are also studied.
文摘1.Introduction:High power microwave technology background and critical applications High power microwave(HPM)is defined as electromagnetic radia-tion exceeding 1 GW peak power or 1 MW average power within the frequency range of 300 MHz to 300 GHz.This perspective focuses on vacuum electronic device-based HPM sources,which rely on controlled magnetic fields for beam confinement and wave-beam interactions.The fundamental operating principle involves the conversion of kinetic energy from high-energy electron beams into electromagnetic energy through beam-wave interactions.
