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RSS2025 Vol. 37, No. 4
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2025,
37: 1-2.
2025,
37: 043001.
doi: 10.11884/HPLPB202537.240274
Abstract:
This paper investigates the application of waveguide slot array antennas in high-power microwave technology and proposes a novel design method, with particular emphasis on the slot coupling, sidelobe levels, and matching between the antenna and the feed. The new method leverages modern computing technology to rapidly compute the slot conductance function considering slot coupling effects, thereby enabling efficient design of waveguide slot array antennas. This method avoids complex calculations or external structures, ensuring system compactness and demonstrating high effectiveness in designing waveguide slot planar arrays. Simulation results indicate that antennas designed using the new method exhibit excellent matching performance. At the center frequency f = 2.458 GHz, the reflection coefficient for each port of antenna designed using the new method ranges from −37.2 dB to −27.7 dB. Compared with the range from −11 dB to −8.7 dB of antennas designed using the Stevenson formula for the same target parameters, the reflection coefficient of antennas designed with the new method is reduced by at least 19 dB. Moreover, the antennas designed with this new method achieve a low sidelobe level of −30.2 dB and a high power capacity of 332.6 MW.
This paper investigates the application of waveguide slot array antennas in high-power microwave technology and proposes a novel design method, with particular emphasis on the slot coupling, sidelobe levels, and matching between the antenna and the feed. The new method leverages modern computing technology to rapidly compute the slot conductance function considering slot coupling effects, thereby enabling efficient design of waveguide slot array antennas. This method avoids complex calculations or external structures, ensuring system compactness and demonstrating high effectiveness in designing waveguide slot planar arrays. Simulation results indicate that antennas designed using the new method exhibit excellent matching performance. At the center frequency f = 2.458 GHz, the reflection coefficient for each port of antenna designed using the new method ranges from −37.2 dB to −27.7 dB. Compared with the range from −11 dB to −8.7 dB of antennas designed using the Stevenson formula for the same target parameters, the reflection coefficient of antennas designed with the new method is reduced by at least 19 dB. Moreover, the antennas designed with this new method achieve a low sidelobe level of −30.2 dB and a high power capacity of 332.6 MW.
2025,
37: 043002.
doi: 10.11884/HPLPB202537.240374
Abstract:
Traditionally, bulky external vacuum pumps are used to obtain and maintain vacuum state of the high power microwave system, which significantly increase the size and weight of the system, and limit its practical application. To achieve lightweight and miniaturization of the high power microwave system and improve its practicality, a vacuum-sealed device is designed for X-band repetitively pulsed high power microwave system. Ceramic-metal brazing technology is used at the interface between the pulse transmission line and diode, as well as between the horn mouth of the microwave antenna and the air, while knife-edge sealing technology is used at other interfaces of the system, thus to achieve vacuum packaging inside the high power microwave generation, transmission, and emission cavity. By using methods of vacuum acquisition in the field of vacuum electronics, such as material surface cleaning and baking, the system can maintain a pressure of the order of 10−7 Pa for nearly 100 h in non-operating conditions. The non-evaporable getter pumps are installed on the cylinder of the diode and the horn of the microwave antenna, which can effectively capture the gas released in the cavity when the system is powered up and maintain vacuum dynamically. The experimental results show that the system can run more than 10 000 shots stably at the pulse repetition frequency of 10−30 Hz.
Traditionally, bulky external vacuum pumps are used to obtain and maintain vacuum state of the high power microwave system, which significantly increase the size and weight of the system, and limit its practical application. To achieve lightweight and miniaturization of the high power microwave system and improve its practicality, a vacuum-sealed device is designed for X-band repetitively pulsed high power microwave system. Ceramic-metal brazing technology is used at the interface between the pulse transmission line and diode, as well as between the horn mouth of the microwave antenna and the air, while knife-edge sealing technology is used at other interfaces of the system, thus to achieve vacuum packaging inside the high power microwave generation, transmission, and emission cavity. By using methods of vacuum acquisition in the field of vacuum electronics, such as material surface cleaning and baking, the system can maintain a pressure of the order of 10−7 Pa for nearly 100 h in non-operating conditions. The non-evaporable getter pumps are installed on the cylinder of the diode and the horn of the microwave antenna, which can effectively capture the gas released in the cavity when the system is powered up and maintain vacuum dynamically. The experimental results show that the system can run more than 10 000 shots stably at the pulse repetition frequency of 10−30 Hz.
2025,
37: 043003.
doi: 10.11884/HPLPB202537.240295
Abstract:
A variable polarization beam scanning antenna based on variable inclination continuous transverse stub antenna (VICTS) antenna and multi-layer all metal cross hole lens is proposed. By adjusting the rotation angles of the polarization layer, radiation layer, and antenna as a whole, free switching between linear polarization and left-hand (right-hand) circular polarization can be achieved, and two-dimensional beam scanning under different polarization outputs can be realized. A K-band antenna with a diameter of 150 mm was designed and simulated. The results show that the maximum gain of the circularly polarized radiation is 27.61 dB, the axial ratio is 1.05 dB, and the aperture efficiency is 58.7%; When the beam is scanned to 26°, the gain is 25.72 dB and the axial ratio is 2.58 dB. The maximum gain of linearly polarized radiation is 27.6 dB, and the aperture efficiency is 58.7%; When the beam is scanned to 26°, the gain is 25.82 dB. According to the metal breakdown threshold of 50 MV/m in vacuum, the power capacity of the VICTS antenna is 9.6 GW/m2, and the power capacity of the polarization layer exceeds 10 GW/m2. This variable polarization beam scanning antenna has the potential to be applied in the high-power microwave field.
A variable polarization beam scanning antenna based on variable inclination continuous transverse stub antenna (VICTS) antenna and multi-layer all metal cross hole lens is proposed. By adjusting the rotation angles of the polarization layer, radiation layer, and antenna as a whole, free switching between linear polarization and left-hand (right-hand) circular polarization can be achieved, and two-dimensional beam scanning under different polarization outputs can be realized. A K-band antenna with a diameter of 150 mm was designed and simulated. The results show that the maximum gain of the circularly polarized radiation is 27.61 dB, the axial ratio is 1.05 dB, and the aperture efficiency is 58.7%; When the beam is scanned to 26°, the gain is 25.72 dB and the axial ratio is 2.58 dB. The maximum gain of linearly polarized radiation is 27.6 dB, and the aperture efficiency is 58.7%; When the beam is scanned to 26°, the gain is 25.82 dB. According to the metal breakdown threshold of 50 MV/m in vacuum, the power capacity of the VICTS antenna is 9.6 GW/m2, and the power capacity of the polarization layer exceeds 10 GW/m2. This variable polarization beam scanning antenna has the potential to be applied in the high-power microwave field.
2025,
37: 043004.
doi: 10.11884/HPLPB202537.240300
Abstract:
This paper presents a modular multi-magnetron unit design based on the mutual coupling phase-locking scheme, configuring it as an axially output module to address the issue of azimuthal non-uniformity in radial output magnetrons in large-scale array applications and significantly improve system robustness. The magnetrons are connected via phase-locking bridges, and the traditional designs based on single magnetron modules lack flexibility. Additionally, due to the non-uniform azimuthal electric field distribution of radial output magnetrons, adding coupling structures to the phase-locking bridge at different positions causes changes in the characteristic impedance of the magnetrons and alters the proportion of energy in the phase-locking bridge relative to the total system energy, thereby affecting output characteristics and phase-locking efficiency. Initially, various topological structures of magnetron phase-locking units were designed and simulated, showing that the opening position and number of the bridge significantly impact phase-locking performance due to the azimuthal field uniformity. Subsequently, an end-to-end series module, suitable for modular design, was selected for further study, and a four-in-one power combiner was designed based on this structure, making the unit output axially. After power synthesis, the output power of the four-tube phase-locking modular unit reached 988 kW, approximately four times that of a single free-running magnetron, with a phase-locking efficiency of 97%.
This paper presents a modular multi-magnetron unit design based on the mutual coupling phase-locking scheme, configuring it as an axially output module to address the issue of azimuthal non-uniformity in radial output magnetrons in large-scale array applications and significantly improve system robustness. The magnetrons are connected via phase-locking bridges, and the traditional designs based on single magnetron modules lack flexibility. Additionally, due to the non-uniform azimuthal electric field distribution of radial output magnetrons, adding coupling structures to the phase-locking bridge at different positions causes changes in the characteristic impedance of the magnetrons and alters the proportion of energy in the phase-locking bridge relative to the total system energy, thereby affecting output characteristics and phase-locking efficiency. Initially, various topological structures of magnetron phase-locking units were designed and simulated, showing that the opening position and number of the bridge significantly impact phase-locking performance due to the azimuthal field uniformity. Subsequently, an end-to-end series module, suitable for modular design, was selected for further study, and a four-in-one power combiner was designed based on this structure, making the unit output axially. After power synthesis, the output power of the four-tube phase-locking modular unit reached 988 kW, approximately four times that of a single free-running magnetron, with a phase-locking efficiency of 97%.
2025,
37: 043005.
doi: 10.11884/HPLPB202537.240288
Abstract:
In this paper, four typical types of high purity graphite and their titanium carbide coating modified materials were tested as anodes in high current electron beam diodes. The results show that the currents of the diodes were obviously different when the graphite anodes were under electron beam bombardment with voltage 860 kV, current 11 kA and pulse width 40 ns. The current curve for graphite 4# was normal even after interaction of 167 electron pulses while the other graphite current curves showed different degrees of tail erosion. The ablative experiments of titanium carbide coating on graphite further verified the difference of the graphite, indicating that the thermal conductivity of graphite has an important effect on its ablative resistance. The higher the thermal conductivity of graphite, the lower the degree of recrystallization of titanium carbide, the better the corrosion resistance of graphite. Therefore, graphite 4# has an excellent resistance to electron beam bombardment and would be promising for application as collector materials in relativistic traveling wave tubes.
In this paper, four typical types of high purity graphite and their titanium carbide coating modified materials were tested as anodes in high current electron beam diodes. The results show that the currents of the diodes were obviously different when the graphite anodes were under electron beam bombardment with voltage 860 kV, current 11 kA and pulse width 40 ns. The current curve for graphite 4# was normal even after interaction of 167 electron pulses while the other graphite current curves showed different degrees of tail erosion. The ablative experiments of titanium carbide coating on graphite further verified the difference of the graphite, indicating that the thermal conductivity of graphite has an important effect on its ablative resistance. The higher the thermal conductivity of graphite, the lower the degree of recrystallization of titanium carbide, the better the corrosion resistance of graphite. Therefore, graphite 4# has an excellent resistance to electron beam bombardment and would be promising for application as collector materials in relativistic traveling wave tubes.
2025,
37: 043006.
doi: 10.11884/HPLPB202537.240340
Abstract:
The complexity of unmanned aerial vehicle (UAV) systems and the diversity of their fault modes present significant challenges to their reliability, stability, and safety. To address the issue of incomplete fault UAV data samples, a fault simulation dataset was constructed using a predefined fault injection method. This dataset is based on four models of faults: bias faults, drift faults, lock faults, and scale faults, allowing equivalent simulation of the drone in fault-free states, actuator failures, and sensor failures. Furthermore, the dataset was evaluated using deep learning networks. Simulation results demonstrate that the three deep learning architectures—WDCNN, ResNet, and QCNN—validate the completeness and effectiveness of the construction method and the fault simulation dataset in this paper. In terms of precision, WDCNN achieved over 82%, ResNet exceeded 90%, and QCNN surpassed 92%. The methods proposed in this study provides a complete dataset and evaluation method for data-driven research on UAV fault diagnosis.
The complexity of unmanned aerial vehicle (UAV) systems and the diversity of their fault modes present significant challenges to their reliability, stability, and safety. To address the issue of incomplete fault UAV data samples, a fault simulation dataset was constructed using a predefined fault injection method. This dataset is based on four models of faults: bias faults, drift faults, lock faults, and scale faults, allowing equivalent simulation of the drone in fault-free states, actuator failures, and sensor failures. Furthermore, the dataset was evaluated using deep learning networks. Simulation results demonstrate that the three deep learning architectures—WDCNN, ResNet, and QCNN—validate the completeness and effectiveness of the construction method and the fault simulation dataset in this paper. In terms of precision, WDCNN achieved over 82%, ResNet exceeded 90%, and QCNN surpassed 92%. The methods proposed in this study provides a complete dataset and evaluation method for data-driven research on UAV fault diagnosis.
2025,
37: 043007.
doi: 10.11884/HPLPB202537.240309
Abstract:
A dual-band antenna based on the quarter-mode substrate integrated waveguide (QMSIW) operating at 5.2GHz and 5.8GHz is designed and implemented. The QMSIW structure reduces the volume of the antenna while maintaining the characteristics of low loss and low profile of the substrate integrated waveguide (SIW). By adding two rows of metallized through holes to the QMSIW and etching two rectangular slots and asymmetric Y-shaped slots, the size is reduced and high isolation is achieved. After testing, the antenna gains at 5.2 GHz and 5.8 GHz are 6.0 and 6.1 dBi, respectively, with cross-polarization ratios greater than 25 dB and 20 dB, respectively. The proposed antenna achieves good miniaturization and high isolation (greater than 34 dB), with dimensions of 0.42λ0×0.42λ0× 0.01λ0. The test results agree well with the simulation results.
A dual-band antenna based on the quarter-mode substrate integrated waveguide (QMSIW) operating at 5.2GHz and 5.8GHz is designed and implemented. The QMSIW structure reduces the volume of the antenna while maintaining the characteristics of low loss and low profile of the substrate integrated waveguide (SIW). By adding two rows of metallized through holes to the QMSIW and etching two rectangular slots and asymmetric Y-shaped slots, the size is reduced and high isolation is achieved. After testing, the antenna gains at 5.2 GHz and 5.8 GHz are 6.0 and 6.1 dBi, respectively, with cross-polarization ratios greater than 25 dB and 20 dB, respectively. The proposed antenna achieves good miniaturization and high isolation (greater than 34 dB), with dimensions of 0.42λ0×0.42λ0× 0.01λ0. The test results agree well with the simulation results.
2025,
37: 044001.
doi: 10.11884/HPLPB202537.240396
Abstract:
Yunguang II accelerator adopts induction voltage adder technique route. The whole system consists of 12 Marx generators, 24 water lines, 12 induction cavities and a long magnetically insulated transmission line. Because of its large scale, many series and complex structure, the alignment measurement technique is required to ensure the whole assembly precision, especially the coaxiality of the induction cavity and the magnetically insulated transmission line. Aiming at the technical defects of complex and complicated measuring system of similar equipment in foreign countries, an all-system alignment measuring scheme using laser tracker as the core means is put forward. The alignment and adjustment of the generator output flange, induction cavity guide rail, magnetically insulation transmission line and its guide rail are completed respectively, especially a measuring mechanism of target base which can realize double-direction inner hole centering is designed. With high precision and efficiency, the alignment measurement and adjustment of 12-stage induction cavity in series is realized, which lays a good technical foundation for the construction of larger-scale facilities.
Yunguang II accelerator adopts induction voltage adder technique route. The whole system consists of 12 Marx generators, 24 water lines, 12 induction cavities and a long magnetically insulated transmission line. Because of its large scale, many series and complex structure, the alignment measurement technique is required to ensure the whole assembly precision, especially the coaxiality of the induction cavity and the magnetically insulated transmission line. Aiming at the technical defects of complex and complicated measuring system of similar equipment in foreign countries, an all-system alignment measuring scheme using laser tracker as the core means is put forward. The alignment and adjustment of the generator output flange, induction cavity guide rail, magnetically insulation transmission line and its guide rail are completed respectively, especially a measuring mechanism of target base which can realize double-direction inner hole centering is designed. With high precision and efficiency, the alignment measurement and adjustment of 12-stage induction cavity in series is realized, which lays a good technical foundation for the construction of larger-scale facilities.
2025,
37: 044002.
doi: 10.11884/HPLPB202537.240276
Abstract:
The electron beam in the electron beam welding machine has the characteristics of high-power density (106−108 W/cm2) and small focal spot size (several hundreds micrometers). Its beam density distribution is an important beam quality parameter and is of great significance to welding process research. However, traditional electron beam density measurement methods, such as fluorescence imaging, cannot be used at such high-power densities. We studied a measurement method based on a combination of a water-cooled Faraday cup with a micro aperture and high-frequency beam scanning. Adding a high-frequency (1−10 kHz) signal to the deflection coil of the electron beam welding machine causes the electron beam to scan within a larger size range, thereby reducing the power density of the electron beam deposited on the surface of the Faraday cup to avoid being burned. Water-cooled Faraday cups that can be used in vacuum chambers are specially designed to take away the heat deposited by the electron beam on the surface of the Faraday cup through water cooling. There is a micro aperture with a size of tens of micrometers on the surface of the Faraday cup. When the electron beam passes through the micro aperture periodically, a small amount of the electron beam passes through the aperture and enters the Faraday cup, forming an electrical signal that is amplified by an amplifier integrated in the Faraday cup and then collected. The electron beam power density distribution can be reconstructed from the collected current signal in the time domain. Experiments have shown that this method can accurately measure the density distribution of high power density electron beams in electron beam welding machines, while having an imaging accuracy of about 23 μm.
The electron beam in the electron beam welding machine has the characteristics of high-power density (106−108 W/cm2) and small focal spot size (several hundreds micrometers). Its beam density distribution is an important beam quality parameter and is of great significance to welding process research. However, traditional electron beam density measurement methods, such as fluorescence imaging, cannot be used at such high-power densities. We studied a measurement method based on a combination of a water-cooled Faraday cup with a micro aperture and high-frequency beam scanning. Adding a high-frequency (1−10 kHz) signal to the deflection coil of the electron beam welding machine causes the electron beam to scan within a larger size range, thereby reducing the power density of the electron beam deposited on the surface of the Faraday cup to avoid being burned. Water-cooled Faraday cups that can be used in vacuum chambers are specially designed to take away the heat deposited by the electron beam on the surface of the Faraday cup through water cooling. There is a micro aperture with a size of tens of micrometers on the surface of the Faraday cup. When the electron beam passes through the micro aperture periodically, a small amount of the electron beam passes through the aperture and enters the Faraday cup, forming an electrical signal that is amplified by an amplifier integrated in the Faraday cup and then collected. The electron beam power density distribution can be reconstructed from the collected current signal in the time domain. Experiments have shown that this method can accurately measure the density distribution of high power density electron beams in electron beam welding machines, while having an imaging accuracy of about 23 μm.
2025,
37: 044003.
doi: 10.11884/HPLPB202537.240279
Abstract:
For the 120 keV positive ion source, the insulation support system for the accelerator was designed, and the connection mode and basic parameters of the insulators and support flanges were determined. The optimization design of the insulation support system was studied through the finite element analysis method for the problems of electric field concentration and connection support. The electrostatic simulations of insulators and grid plates were carried out to determine the material and structural parameters of insulators, so as to study the insulating properties of the accelerator. The study shows that the maximum electric field around each insulator is less than 4 kV/mm, and the maximum electric field between grids is about 14 kV/mm, which can meet the voltage withstand requirements of 120 keV positive ion source accelerator. Secondly, considering the vertical installation of ion source, the connecting bolts of EG support flange and insulator would bear great normal stress and shear stress under the action of ion source gravity, thus the mechanical properties of the accelerator were studied. After mechanical analysis, the maximum normal stress of the bolt is 26.336 MPa, and the shear force is 1.292 MPa. The maximum normal stress of the bolt in the finite element analysis is 25.867 MPa, which is 1.78% different from the theoretical solution and less than the tensile strength of the material. The maximum shear force is 1.295 MPa, which is 0.23% different from the theoretical solution and less than the shear strength of the material. The results show that the mechanical properties of the 120 keV positive ion source accelerator meet the design requirements.
For the 120 keV positive ion source, the insulation support system for the accelerator was designed, and the connection mode and basic parameters of the insulators and support flanges were determined. The optimization design of the insulation support system was studied through the finite element analysis method for the problems of electric field concentration and connection support. The electrostatic simulations of insulators and grid plates were carried out to determine the material and structural parameters of insulators, so as to study the insulating properties of the accelerator. The study shows that the maximum electric field around each insulator is less than 4 kV/mm, and the maximum electric field between grids is about 14 kV/mm, which can meet the voltage withstand requirements of 120 keV positive ion source accelerator. Secondly, considering the vertical installation of ion source, the connecting bolts of EG support flange and insulator would bear great normal stress and shear stress under the action of ion source gravity, thus the mechanical properties of the accelerator were studied. After mechanical analysis, the maximum normal stress of the bolt is 26.336 MPa, and the shear force is 1.292 MPa. The maximum normal stress of the bolt in the finite element analysis is 25.867 MPa, which is 1.78% different from the theoretical solution and less than the tensile strength of the material. The maximum shear force is 1.295 MPa, which is 0.23% different from the theoretical solution and less than the shear strength of the material. The results show that the mechanical properties of the 120 keV positive ion source accelerator meet the design requirements.
2025,
37: 044004.
doi: 10.11884/HPLPB202537.240285
Abstract:
To carry out research on the overall technology of C-band miniaturized accelerators under localization conditions, the Institute of Applied Electronics of the Chinese Academy of Engineering Physics has developed various C-band miniaturized standing wave accelerator tubes. At the same time, a C-band accelerator X-ray source system with mainly domestic components (magnetron, ring resonator, high-voltage power supply, etc.) has been established, and further high-power hot test experiments have been carried out using the accelerator as a testing platform. In the hot test experiment, the main performance indicators of the accelerator were tested according to the testing principles and methods specified in the national standard “GB/T 20129-2015 Electron Linear Accelerator for Non-destructive Testing”. The energy of the accelerator was tested using the steel attenuation method, and the focal size of the accelerator was tested using the “sandwich” method. The final test results indicate that the accelerator focal size is approximately 1.2 mm, and the accelerator’s energy can be continuously adjusted within the range of 3-4 MeV. The dose rate fluctuation of the accelerator within 20 minutes is less than ± 3%. The research results indicate that the supporting environment and overall performance of domestic C-band miniaturized accelerator can basically meet the development and use requirements of miniaturized accelerator systems.
To carry out research on the overall technology of C-band miniaturized accelerators under localization conditions, the Institute of Applied Electronics of the Chinese Academy of Engineering Physics has developed various C-band miniaturized standing wave accelerator tubes. At the same time, a C-band accelerator X-ray source system with mainly domestic components (magnetron, ring resonator, high-voltage power supply, etc.) has been established, and further high-power hot test experiments have been carried out using the accelerator as a testing platform. In the hot test experiment, the main performance indicators of the accelerator were tested according to the testing principles and methods specified in the national standard “GB/T 20129-2015 Electron Linear Accelerator for Non-destructive Testing”. The energy of the accelerator was tested using the steel attenuation method, and the focal size of the accelerator was tested using the “sandwich” method. The final test results indicate that the accelerator focal size is approximately 1.2 mm, and the accelerator’s energy can be continuously adjusted within the range of 3-4 MeV. The dose rate fluctuation of the accelerator within 20 minutes is less than ± 3%. The research results indicate that the supporting environment and overall performance of domestic C-band miniaturized accelerator can basically meet the development and use requirements of miniaturized accelerator systems.
2025,
37: 044005.
doi: 10.11884/HPLPB202537.240286
Abstract:
The Rhodotron is a compact and highly efficient accelerator. This accelerator requires an electron gun with high repetition frequency, short pulses and low emittance, to ensure optimal acceleration performance. This paper shows the physical design, simulation, prototype development and beam testing of such an electron gun. The electron gun is designed as a grid-controlled electron gun based on a barium-tungsten thermionic cathode. The electron gun adopts a Pierce structure. It has a cathode voltage of −40 kV, an operating repetition frequency of 10.75 MHz, a design emission current of 200 mA maximum, and a single minimum pulse length of 3 ns. In the actual test, the electron gun measured a peak emission current of 204 mA with the cathode heater operating at 0.95 A/6.7 V, loaded cathode DC voltage −40 kV, and gate control voltage 290 V/10 MHz. When the beam pulse length is 2.7 ns, the beam current amplitude is 39.2 mA, and the actual beam emittance is less than 2 mm mrad. This result meets the design and accelerator application requirements.
The Rhodotron is a compact and highly efficient accelerator. This accelerator requires an electron gun with high repetition frequency, short pulses and low emittance, to ensure optimal acceleration performance. This paper shows the physical design, simulation, prototype development and beam testing of such an electron gun. The electron gun is designed as a grid-controlled electron gun based on a barium-tungsten thermionic cathode. The electron gun adopts a Pierce structure. It has a cathode voltage of −40 kV, an operating repetition frequency of 10.75 MHz, a design emission current of 200 mA maximum, and a single minimum pulse length of 3 ns. In the actual test, the electron gun measured a peak emission current of 204 mA with the cathode heater operating at 0.95 A/6.7 V, loaded cathode DC voltage −40 kV, and gate control voltage 290 V/10 MHz. When the beam pulse length is 2.7 ns, the beam current amplitude is 39.2 mA, and the actual beam emittance is less than 2 mm mrad. This result meets the design and accelerator application requirements.
2025,
37: 044006.
doi: 10.11884/HPLPB202537.240343
Abstract:
The Anhui Laboratory of Advanced Photon Science and Technology has beer developing a 6 MeV compact microtron, which can be used to drive compact microfocus X-ray sources or compact terahertz free electron lasers. To achieve a more compact accelerator design, the CST Electromagnetic suite was used to design and calculate the second type RF cavity of the microtron. The frequency of the RF cavity is2998.2 MHz, and an accelerating voltage of over 1 MV can be obtained in the RF cavity gap. The electron energy gain can reach about 0.9 MeV per pass. At the same time, CST Particle Studio was used to simulate the electron generation and acceleration process in the ultra-high frequency cavity with thermionic cathode. The effects of microwave power amplitude, magnetic field strength, cathode emission position, and beam channel on the microtron were studied. The coupler design considering beam loading was also completed, and the operating parameters of the RF cavity during steady-state operation were obtained. The simulation results show that when the beam loading reaches steady state, with a cathode emission capacity of 20 A/cm2, a current of 24 mA can be induced, a beam energy of 6 MeV, an energy spread of 0.64%, and a transverse RMS size of 3.3 mm × 1.8 mm can be obtained.
The Anhui Laboratory of Advanced Photon Science and Technology has beer developing a 6 MeV compact microtron, which can be used to drive compact microfocus X-ray sources or compact terahertz free electron lasers. To achieve a more compact accelerator design, the CST Electromagnetic suite was used to design and calculate the second type RF cavity of the microtron. The frequency of the RF cavity is
2025,
37: 044007.
doi: 10.11884/HPLPB202537.240419
Abstract:
Beam profile is one of the key performance indicators for high-intensity proton accelerators. A new residual gas ionization profile monitor has been installed at the Linac of the China Spallation Neutron Source for non-destructive, real-time measurement of parameters such as the transverse beam profile at critical locations. This paper presents the selection, structural design rationale, and beam test results of this profile monitor. The detector adopts a compact structure, offering a high-resolution design within a limited space. The compact design eliminates the equipotential strips that uniformly act on the electric field and adds a field grid at the lower plate apertures to improve the uniformity of the electric field and reduce the electric field components. Beam tests evaluated the performance of the new detector in measuring orbit and profile parameters, with calibration performed in comparison to the BPM near the detector’s location. The error between the transverse profile measurement and theoretical calculation was less than 8.3%, meeting the beam measurement requirements.
Beam profile is one of the key performance indicators for high-intensity proton accelerators. A new residual gas ionization profile monitor has been installed at the Linac of the China Spallation Neutron Source for non-destructive, real-time measurement of parameters such as the transverse beam profile at critical locations. This paper presents the selection, structural design rationale, and beam test results of this profile monitor. The detector adopts a compact structure, offering a high-resolution design within a limited space. The compact design eliminates the equipotential strips that uniformly act on the electric field and adds a field grid at the lower plate apertures to improve the uniformity of the electric field and reduce the electric field components. Beam tests evaluated the performance of the new detector in measuring orbit and profile parameters, with calibration performed in comparison to the BPM near the detector’s location. The error between the transverse profile measurement and theoretical calculation was less than 8.3%, meeting the beam measurement requirements.
2025,
37: 044008.
doi: 10.11884/HPLPB202537.240278
Abstract:
In high-current accelerator beam tubes, the flow of charged particles induces a high-frequency field within the tube, which affects the current and stability of the beam. Additionally, this field leads to extra heat loss during the operation of the superconducting cavity, impacting its operational stability. Therefore, it is necessary to effectively control the high-order mode. This study employs ferrite as an absorbing material to absorb high-order modes. The ferrites were welded to copper substrates through metallization and brazing, and then they were joined with the copper beam tube and cooling system to create a ferrite high-order mode damper. The microwave performance of the ferrite high-order mode damper at various frequencies was simulated using CST software, and compared with the measured results. It is found that the high-order mode can be effectively suppressed in the test frequency band, but there are some differences between the two results in a certain frequency band. Additionally, COMSOL software was utilized to simulate the temperature distribution of the ferrite high-order mode damper during operation, and these simulations were compared with experimental data. The test results for loaded power show that the absorption efficiency reaches 77.4% when the absorbed power is 10.14 kW. Furthermore, results of vacuum leak rates, ultimate vacuum and water-resistant all conform to the design requirements for superconducting high-frequency cavities.
In high-current accelerator beam tubes, the flow of charged particles induces a high-frequency field within the tube, which affects the current and stability of the beam. Additionally, this field leads to extra heat loss during the operation of the superconducting cavity, impacting its operational stability. Therefore, it is necessary to effectively control the high-order mode. This study employs ferrite as an absorbing material to absorb high-order modes. The ferrites were welded to copper substrates through metallization and brazing, and then they were joined with the copper beam tube and cooling system to create a ferrite high-order mode damper. The microwave performance of the ferrite high-order mode damper at various frequencies was simulated using CST software, and compared with the measured results. It is found that the high-order mode can be effectively suppressed in the test frequency band, but there are some differences between the two results in a certain frequency band. Additionally, COMSOL software was utilized to simulate the temperature distribution of the ferrite high-order mode damper during operation, and these simulations were compared with experimental data. The test results for loaded power show that the absorption efficiency reaches 77.4% when the absorbed power is 10.14 kW. Furthermore, results of vacuum leak rates, ultimate vacuum and water-resistant all conform to the design requirements for superconducting high-frequency cavities.
2025,
37: 044009.
doi: 10.11884/HPLPB202537.240236
Abstract:
At the initial stage of beam commissioning, the turn-by-turn beam loss signals from the electron storage ring directly display the injection and accumulation of the beam. This paper introduces the types of beam loss mechanisms and enumerates several common types of beam loss monitors and their parameters. Based on the parameters of the upgrade project of the Beijing Electron Positron Collider (BEPCII) , beam loss was simulated using Geant4. The distribution of shower electrons and photons outside the vacuum chamber was analyzed. A scintillator coupled with a photomultiplier tube (PMT) monitor was chosen to detect the turn-by-turn beam loss signals. Beam tests were conducted at BEPCII, and the self-developed electronic system was used for signal acquisition and processing. To address the issue of inconsistent performance among scintillator beam loss monitors, sensitivity calibration was performed, followed by beam verification at BEPCII. This paper also introduces the signal acquisition and processing in electronics, along with the calculation and analysis of the measurement accuracy. These experiments has laid the foundation for the application of scintillation beam loss monitors in high energy photon source.
At the initial stage of beam commissioning, the turn-by-turn beam loss signals from the electron storage ring directly display the injection and accumulation of the beam. This paper introduces the types of beam loss mechanisms and enumerates several common types of beam loss monitors and their parameters. Based on the parameters of the upgrade project of the Beijing Electron Positron Collider (BEPCII) , beam loss was simulated using Geant4. The distribution of shower electrons and photons outside the vacuum chamber was analyzed. A scintillator coupled with a photomultiplier tube (PMT) monitor was chosen to detect the turn-by-turn beam loss signals. Beam tests were conducted at BEPCII, and the self-developed electronic system was used for signal acquisition and processing. To address the issue of inconsistent performance among scintillator beam loss monitors, sensitivity calibration was performed, followed by beam verification at BEPCII. This paper also introduces the signal acquisition and processing in electronics, along with the calculation and analysis of the measurement accuracy. These experiments has laid the foundation for the application of scintillation beam loss monitors in high energy photon source.
2025,
37: 044010.
doi: 10.11884/HPLPB202537.240388
Abstract:
To observe whether the high-power electron accelerator achieves the design index performance and disinfection effect, the performance of the high-power electron accelerator using the methods and procedures specified in the standard was tested and evaluated, and the inactivation effect of the electron beam output from the electron accelerator on microorganisms such as Staphylococcus aureus, Escherichia coli, Bacillus cereus, coronavirus, was explored. At the same time, examined how different material loads affected the inactivation efficiency. The high-power electron accelerator, can output a high-energy electron beam with an energy of 10.27 MeV and a power of 25 kW and it was found to have a certain level of penetration capability for surrogate materials. The electron beam achieves a disinfection effect of 3 log reductions or higher against microorganisms such as Staphylococcus aureus, Escherichia coli, Bacillus cereus, and coronaviruses. After penetrating a certain thickness of load material, the electron beam can still achieve a disinfection effect of 3 log reductions or higher against Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Bacillus subtilis (black variant) spores. The designed electron accelerator meets the performance specifications and has a certain level of penetration capacity, effectively achieving the required disinfection effect against the studied microorganisms.
To observe whether the high-power electron accelerator achieves the design index performance and disinfection effect, the performance of the high-power electron accelerator using the methods and procedures specified in the standard was tested and evaluated, and the inactivation effect of the electron beam output from the electron accelerator on microorganisms such as Staphylococcus aureus, Escherichia coli, Bacillus cereus, coronavirus, was explored. At the same time, examined how different material loads affected the inactivation efficiency. The high-power electron accelerator, can output a high-energy electron beam with an energy of 10.27 MeV and a power of 25 kW and it was found to have a certain level of penetration capability for surrogate materials. The electron beam achieves a disinfection effect of 3 log reductions or higher against microorganisms such as Staphylococcus aureus, Escherichia coli, Bacillus cereus, and coronaviruses. After penetrating a certain thickness of load material, the electron beam can still achieve a disinfection effect of 3 log reductions or higher against Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Bacillus subtilis (black variant) spores. The designed electron accelerator meets the performance specifications and has a certain level of penetration capacity, effectively achieving the required disinfection effect against the studied microorganisms.
2025,
37: 044011.
doi: 10.11884/HPLPB202537.240404
Abstract:
A scintillator detector for monitoring dense plasma focus (DPF) device neutron yield and waveform was developed. The size parameters of the scintillator were determined by simulating the curve of the variation of the photons emitted by the scintillator with the thickness, and the sensitivity of the detector was obtained by relative calibration. The scattering distribution in the experimental environment was simulated according to the Monte-Carlo method, and the experimental layout was designed according to factors such as the linear range of the probe. The D-D pulse neutron yield and time waveform of the self-developed DPF device were measured using the developed scintillator detector, and the measurement results were analyzed and discussed. The test results indicate that the scintillation detector has detected the hard X-rays and neutron waveforms generated by the DPF device. The time difference between their peak signals matches the flight time of 2.45 MeV neutrons, with a neutron pulse width of about hundreds of nanoseconds.
A scintillator detector for monitoring dense plasma focus (DPF) device neutron yield and waveform was developed. The size parameters of the scintillator were determined by simulating the curve of the variation of the photons emitted by the scintillator with the thickness, and the sensitivity of the detector was obtained by relative calibration. The scattering distribution in the experimental environment was simulated according to the Monte-Carlo method, and the experimental layout was designed according to factors such as the linear range of the probe. The D-D pulse neutron yield and time waveform of the self-developed DPF device were measured using the developed scintillator detector, and the measurement results were analyzed and discussed. The test results indicate that the scintillation detector has detected the hard X-rays and neutron waveforms generated by the DPF device. The time difference between their peak signals matches the flight time of 2.45 MeV neutrons, with a neutron pulse width of about hundreds of nanoseconds.
2025,
37: 045001.
doi: 10.11884/HPLPB202537.240319
Abstract:
This paper presents the design of a D-dot monitor for measuring nanosecond high voltage pulses, including the design, simulation, and experiments of the probe and integrator. The electrode of the probe can be replaced and its axial length can be adjusted according to different measurement requirements. The structure of the probe is optimized according to the results of simulation on electrostatic field by CST. The amplitude-frequency response of the monitor is simulated by Pspice to ensure that the operating frequency of the monitor meets the design requirements. The D-dot monitor is applied to measure the high voltage pulses with nanosecond level pulse width. The experimental results show that the D-dot monitor meets the measurement requirements for high voltage pulses with rise time of about 37 ns and voltage amplitude of about 597 kV.
This paper presents the design of a D-dot monitor for measuring nanosecond high voltage pulses, including the design, simulation, and experiments of the probe and integrator. The electrode of the probe can be replaced and its axial length can be adjusted according to different measurement requirements. The structure of the probe is optimized according to the results of simulation on electrostatic field by CST. The amplitude-frequency response of the monitor is simulated by Pspice to ensure that the operating frequency of the monitor meets the design requirements. The D-dot monitor is applied to measure the high voltage pulses with nanosecond level pulse width. The experimental results show that the D-dot monitor meets the measurement requirements for high voltage pulses with rise time of about 37 ns and voltage amplitude of about 597 kV.
2025,
37: 045002.
doi: 10.11884/HPLPB202537.240416
Abstract:
The study on the self-breakdown characteristics of air-insulated gas switches at different environmental temperatures can improve the adaptability of pulsed power devices, especially in the fields of shale oil and gas resource exploitation. By establishing a research platform for the high-temperature performance study of coaxial gas switches, the self-breakdown voltage distribution of gas switches at different temperatures was experimentally studied. The main factors and laws of temperature on the self-breakdown discharge process were analyzed in combination with Townsend discharge theory. The results show that, the main factors affecting the self-breakdown voltage are the density of the air and the distance of the switch at different temperatures. For cavity-exchangeable gas switches, the self-breakdown voltage decreases with the increase of temperature. However, with the increase of environmental temperature, the high-temperature particles sprayed during the ablation process of the electrode cause molecular pyrolysis and gas adsorption on the surface of the insulating material, as well as the chemical reaction of gas molecules in the process of high-current discharge, resulting in obvious changes in the composition of the gas and the reduction of the stability of the switch discharge. The research results in this paper can provide a technical reference for the reliable operation of gas switches in high-temperature environments.
The study on the self-breakdown characteristics of air-insulated gas switches at different environmental temperatures can improve the adaptability of pulsed power devices, especially in the fields of shale oil and gas resource exploitation. By establishing a research platform for the high-temperature performance study of coaxial gas switches, the self-breakdown voltage distribution of gas switches at different temperatures was experimentally studied. The main factors and laws of temperature on the self-breakdown discharge process were analyzed in combination with Townsend discharge theory. The results show that, the main factors affecting the self-breakdown voltage are the density of the air and the distance of the switch at different temperatures. For cavity-exchangeable gas switches, the self-breakdown voltage decreases with the increase of temperature. However, with the increase of environmental temperature, the high-temperature particles sprayed during the ablation process of the electrode cause molecular pyrolysis and gas adsorption on the surface of the insulating material, as well as the chemical reaction of gas molecules in the process of high-current discharge, resulting in obvious changes in the composition of the gas and the reduction of the stability of the switch discharge. The research results in this paper can provide a technical reference for the reliable operation of gas switches in high-temperature environments.
2025,
37: 055003.
doi: 10.11884/HPLPB202537.240275
Abstract:
In this study, Cr2O3 was applied to the surface of Al2O3 ceramic via a dip-coating method. Subsequently, the final coated ceramic was obtained through high-temperature sintering. The effects of the Cr2O3 coating on material composition, microstructure, secondary electron emission coefficient, surface resistivity, and vacuum surface hold-off voltage performance were systematically investigated. The results indicate that the surface of the coated ceramic appears dark red, representing a mixture of three materials: Al2O3-Cr2O3 solid solution, MgAl2O4, and Cr2O3. Compared to the Al2O3 ceramic, both the grain size and pore size on the surface are reduced, and the homogeneity of the grain size is significantly enhanced. After high-temperature sintering, Al and Cr diffuse into each other. Additionally, a small amount of glass phase, likely migrating from the ceramic substrate, is detected in the coating. Owing to the high-temperature sintering of the Cr2O3 coating, the secondary electron emission coefficient is reduced to 3.22, and the surface resistivity is also lowered to 4.52×1011 Ω. Furthermore, the vacuum surface hold-off electric field strength of the coated ceramic increases to 34.44 kV/cm, which is approximately 108% higher than that of the Al2O3 ceramic.
In this study, Cr2O3 was applied to the surface of Al2O3 ceramic via a dip-coating method. Subsequently, the final coated ceramic was obtained through high-temperature sintering. The effects of the Cr2O3 coating on material composition, microstructure, secondary electron emission coefficient, surface resistivity, and vacuum surface hold-off voltage performance were systematically investigated. The results indicate that the surface of the coated ceramic appears dark red, representing a mixture of three materials: Al2O3-Cr2O3 solid solution, MgAl2O4, and Cr2O3. Compared to the Al2O3 ceramic, both the grain size and pore size on the surface are reduced, and the homogeneity of the grain size is significantly enhanced. After high-temperature sintering, Al and Cr diffuse into each other. Additionally, a small amount of glass phase, likely migrating from the ceramic substrate, is detected in the coating. Owing to the high-temperature sintering of the Cr2O3 coating, the secondary electron emission coefficient is reduced to 3.22, and the surface resistivity is also lowered to 4.52×1011 Ω. Furthermore, the vacuum surface hold-off electric field strength of the coated ceramic increases to 34.44 kV/cm, which is approximately 108% higher than that of the Al2O3 ceramic.
2025,
37: 045004.
doi: 10.11884/HPLPB202537.240336
Abstract:
A pulse generator based on pulse forming line and variable impedance transmission line of glycerol medium is studied. The generator is composed of a gas main switch at its rear, a Tesla transformer, a double helix Blumlein line, a variable impedance transmission line and a load. This paper mainly researches the design of insulation and voltage resistance technology of the double helix Blumlein line and the variable impedance transmission line in the common outer cylinder, and the influence of switch position on the output waveform of the generator. Through theoretical analysis, simulation, structural optimization and experimental research, key problems such as structural design, insulation and voltage resistance and load matching are solved. Thus, the compactness and miniaturization of the driving source are improved. The experimental results show that the high power pulse generator can realize quasi-square wave pulse signal with the output peak voltage of 177 kV, the output pulse width of 101.4 ns on the load of 50 Ω.
A pulse generator based on pulse forming line and variable impedance transmission line of glycerol medium is studied. The generator is composed of a gas main switch at its rear, a Tesla transformer, a double helix Blumlein line, a variable impedance transmission line and a load. This paper mainly researches the design of insulation and voltage resistance technology of the double helix Blumlein line and the variable impedance transmission line in the common outer cylinder, and the influence of switch position on the output waveform of the generator. Through theoretical analysis, simulation, structural optimization and experimental research, key problems such as structural design, insulation and voltage resistance and load matching are solved. Thus, the compactness and miniaturization of the driving source are improved. The experimental results show that the high power pulse generator can realize quasi-square wave pulse signal with the output peak voltage of 177 kV, the output pulse width of 101.4 ns on the load of 50 Ω.
2025,
37: 045005.
doi: 10.11884/HPLPB202537.240284
Abstract:
Numerous studies have demonstrated that vertical graphene coatings on material surfaces can significantly reduce the secondary electron yield, with the maximum secondary electron yield typically occurring at incident electron energies in the range of hundreds of electron volts. Under actual electron beam irradiation conditions, the microstructure of vertical graphene undergoes complex dynamic evolution processes. These structural changes exhibit diverse characteristic patterns, leading to varying degrees of alteration in secondary electron emission properties, with distinct underlying mechanisms. To systematically investigate the influence of electron beam irradiation parameters on the microstructural evolution of vertical graphene and its secondary electron emission characteristics, employing a combined approach of theoretical simulation and experimental verification, this study has independently designed and developed a dedicated electron beam irradiation system specifically for vertical graphene research.
Numerous studies have demonstrated that vertical graphene coatings on material surfaces can significantly reduce the secondary electron yield, with the maximum secondary electron yield typically occurring at incident electron energies in the range of hundreds of electron volts. Under actual electron beam irradiation conditions, the microstructure of vertical graphene undergoes complex dynamic evolution processes. These structural changes exhibit diverse characteristic patterns, leading to varying degrees of alteration in secondary electron emission properties, with distinct underlying mechanisms. To systematically investigate the influence of electron beam irradiation parameters on the microstructural evolution of vertical graphene and its secondary electron emission characteristics, employing a combined approach of theoretical simulation and experimental verification, this study has independently designed and developed a dedicated electron beam irradiation system specifically for vertical graphene research.
2025,
37: 045006.
doi: 10.11884/HPLPB202537.240434
Abstract:
Dielectric barrier discharge (DBD) technology, an emerging method for air disinfection, has drawn considerable interest due to its capacity to generate low-temperature plasma at ambient temperatures, thereby effectively neutralizing airborne bacteria and viruses. To cater to the practical requirements of DBD technology, the development of a DBD discharge pulse power supply has been successfully completed. This power supply incorporates a voltage doubling circuit to charge the front-stage capacitor, not only ensuring the zero-current shutdown of the IGBT (insulated gate bipolar transistor) but also mitigating the risk of breakdown potentially caused by short circuits in the back-stage to the solid-state switch. By leveraging the voltage amplification of a pulse transformer in conjunction with the pulse sharpening effect of a magnetic switch, the system achieves a rapid leading edge and a high peak load output voltage. This design not only alleviates the load on the preamplifier system but also substantially enhances the system’s lifespan and operational frequency. Experimental data reveal that the peak load output voltage of this power supply can reach 27 kV, with a pulse width of 650 ns, a pulse rise time of 60 ns, and a continuously adjustable repetition frequency ranging from 0 to 500 Hz
Dielectric barrier discharge (DBD) technology, an emerging method for air disinfection, has drawn considerable interest due to its capacity to generate low-temperature plasma at ambient temperatures, thereby effectively neutralizing airborne bacteria and viruses. To cater to the practical requirements of DBD technology, the development of a DBD discharge pulse power supply has been successfully completed. This power supply incorporates a voltage doubling circuit to charge the front-stage capacitor, not only ensuring the zero-current shutdown of the IGBT (insulated gate bipolar transistor) but also mitigating the risk of breakdown potentially caused by short circuits in the back-stage to the solid-state switch. By leveraging the voltage amplification of a pulse transformer in conjunction with the pulse sharpening effect of a magnetic switch, the system achieves a rapid leading edge and a high peak load output voltage. This design not only alleviates the load on the preamplifier system but also substantially enhances the system’s lifespan and operational frequency. Experimental data reveal that the peak load output voltage of this power supply can reach 27 kV, with a pulse width of 650 ns, a pulse rise time of 60 ns, and a continuously adjustable repetition frequency ranging from 0 to 500 Hz
2025,
37: 045007.
doi: 10.11884/HPLPB202537.240341
Abstract:
The gas-puff load is widely used in the Z-pinch researches because of its simple installation and excellent performance. The initial distribution of the gas-flow mass of the puff load is the most important parameter for optimizing the nozzle size structure, improving the implosion dynamics process, and finally improving the X-ray radiation yield. In this paper, the feasibility of using Rayleigh scattering to diagnose the airflow field of a gas-puff is introduced. The time-resolved images of the airflow filed have been obtained. The images show that the gas flowing from the nozzle forms a hollow shell with lower density within the length 1 cm and the flow expands in radical direction like a horn. The experimental images are compared with the calculation results using the ballistic-gas-flow model, and it is found that the model can well illustrate the flow field if the parameters are selected properly. The density of the airflow deduced from the Rayleigh scattering images is 3−4 orders of magnitude higher than the calculated results by ballistic transport model. The reason is that clusters are formed when the airflow field is in low temperature and low density, and they can greatly increase the Rayleigh scattering effect of gas flow. Nevertheless, the relative intensity distribution of the gas flow field can be obtained by the Rayleigh scattering with distinct details.
The gas-puff load is widely used in the Z-pinch researches because of its simple installation and excellent performance. The initial distribution of the gas-flow mass of the puff load is the most important parameter for optimizing the nozzle size structure, improving the implosion dynamics process, and finally improving the X-ray radiation yield. In this paper, the feasibility of using Rayleigh scattering to diagnose the airflow field of a gas-puff is introduced. The time-resolved images of the airflow filed have been obtained. The images show that the gas flowing from the nozzle forms a hollow shell with lower density within the length 1 cm and the flow expands in radical direction like a horn. The experimental images are compared with the calculation results using the ballistic-gas-flow model, and it is found that the model can well illustrate the flow field if the parameters are selected properly. The density of the airflow deduced from the Rayleigh scattering images is 3−4 orders of magnitude higher than the calculated results by ballistic transport model. The reason is that clusters are formed when the airflow field is in low temperature and low density, and they can greatly increase the Rayleigh scattering effect of gas flow. Nevertheless, the relative intensity distribution of the gas flow field can be obtained by the Rayleigh scattering with distinct details.
