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, Available online , doi: 10.11884/HPLPB202537.240352
Abstract:
As an advanced 4th generation synchrotron radiation facility, the Shenzhen Innovation Light-source Facility (SILF) storage ring is based on multi-bend achromat (MBA) lattices, enabling one to two orders of magnitude reduction in beam emittance compared to the 3rd generation storage ring. This significantly enhance the radiation brightness and coherence. The multipole magnets of many types for SILF storage ring are under preliminary design, which require high integral field homogeneity. As a result, a dedicated pole tip optimization procedure with high efficiency is developed for quadrupole and sextupole magnets with Opera-2D® python script. The procedure considers also the 3D field effect which makes the optimization more straightforward. In this paper, the design of the quadrupole and sextupole magnets for SILF storage ring is first presented, followed by a detailed description of the implemented pole shape optimization method.
As an advanced 4th generation synchrotron radiation facility, the Shenzhen Innovation Light-source Facility (SILF) storage ring is based on multi-bend achromat (MBA) lattices, enabling one to two orders of magnitude reduction in beam emittance compared to the 3rd generation storage ring. This significantly enhance the radiation brightness and coherence. The multipole magnets of many types for SILF storage ring are under preliminary design, which require high integral field homogeneity. As a result, a dedicated pole tip optimization procedure with high efficiency is developed for quadrupole and sextupole magnets with Opera-2D® python script. The procedure considers also the 3D field effect which makes the optimization more straightforward. In this paper, the design of the quadrupole and sextupole magnets for SILF storage ring is first presented, followed by a detailed description of the implemented pole shape optimization method.
, Available online , doi: 10.11884/HPLPB202537.240131
Abstract:
The petawatt laser-driven proton accelerator at Peking University develops a laser proton radiotherapy system in response to the needs of proton radiation tumor treatment. The common collection section of its horizontal and vertical beam lines mainly consists of three superconducting solenoids (S1-S3). Large stresses are generated in the solenoids during the cooling down and excitation process, in addition, the superconducting solenoids are operated by fast ramping, and the AC loss in the process will have an important impact on the solenoid excitation speed and stable operation. In this paper, the highest field strength and the most complex structure of 7.8T-120 mm solenoid S1 is taken as the research object, COMSOL Multiphysics software is used to carry out the stress analysis of superconducting solenoids under multi-field conditions, and at the same time, the simulation of the AC loss due to the rapid change of the current is carried out. The corresponding experimental studies were carried out to obtain the variation curves of strain with temperature, correlations between current, magnetic field and strain correspondingly. According to the experiment data, there is a significant positive correlation between the measured values of the magnetic field, the strain and the change of current, which verifies the rationality of the superconducting solenoid design. This study provides experience and reference for the subsequent design and development of similar superconducting magnets.
The petawatt laser-driven proton accelerator at Peking University develops a laser proton radiotherapy system in response to the needs of proton radiation tumor treatment. The common collection section of its horizontal and vertical beam lines mainly consists of three superconducting solenoids (S1-S3). Large stresses are generated in the solenoids during the cooling down and excitation process, in addition, the superconducting solenoids are operated by fast ramping, and the AC loss in the process will have an important impact on the solenoid excitation speed and stable operation. In this paper, the highest field strength and the most complex structure of 7.8T-120 mm solenoid S1 is taken as the research object, COMSOL Multiphysics software is used to carry out the stress analysis of superconducting solenoids under multi-field conditions, and at the same time, the simulation of the AC loss due to the rapid change of the current is carried out. The corresponding experimental studies were carried out to obtain the variation curves of strain with temperature, correlations between current, magnetic field and strain correspondingly. According to the experiment data, there is a significant positive correlation between the measured values of the magnetic field, the strain and the change of current, which verifies the rationality of the superconducting solenoid design. This study provides experience and reference for the subsequent design and development of similar superconducting magnets.
, Available online , doi: 10.11884/HPLPB202537.240270
Abstract:
Traditional methods for analyzing superconduction radio-frequency (SRF) cavity faults rely on a priori knowledge, featuring high labor and time costs, poor accuracy and low consistency. They are less efficient when dealing with complex devices and large amounts of data. In this paper, a method for classifying SRF cavity faults based on machine learning algorithms is investigated. Using the SRF cavity fault data generated during the operation of BEPCII, the classification of SRF cavity faults is achieved through image information extraction, feature selection and optimization, machine learning algorithm training, and analyzing the accuracy and consistency of the model via K-fold cross validation. The results of the study show that Random Forest, Support Vector Machine and Bagging algorithms have better classification results when dealing with faulty pictures. The accuracy and consistency of supervised learning methods are significantly higher than those of unsupervised learning. The fault classification realized in this research achieves high accuracy and consistency. It enables to quickly and efficiently distinguish the faults occurring on the SRF cavity of BEPCII. It also provides a reference for the diagnosis of SRF cavity faults in other particle accelerators.
Traditional methods for analyzing superconduction radio-frequency (SRF) cavity faults rely on a priori knowledge, featuring high labor and time costs, poor accuracy and low consistency. They are less efficient when dealing with complex devices and large amounts of data. In this paper, a method for classifying SRF cavity faults based on machine learning algorithms is investigated. Using the SRF cavity fault data generated during the operation of BEPCII, the classification of SRF cavity faults is achieved through image information extraction, feature selection and optimization, machine learning algorithm training, and analyzing the accuracy and consistency of the model via K-fold cross validation. The results of the study show that Random Forest, Support Vector Machine and Bagging algorithms have better classification results when dealing with faulty pictures. The accuracy and consistency of supervised learning methods are significantly higher than those of unsupervised learning. The fault classification realized in this research achieves high accuracy and consistency. It enables to quickly and efficiently distinguish the faults occurring on the SRF cavity of BEPCII. It also provides a reference for the diagnosis of SRF cavity faults in other particle accelerators.
, Available online , doi: 10.11884/HPLPB202537.240435
Abstract:
With the in-depth study of particle accelerator physics experiments, the requirements higher for beam quality have gradually increased. To obtain a magnetic field environment with extremely high stability and extremely low noise, a high-precision DC excitation power supply combining switching mode and linear mode was analyzed and designed. The front-end switching power supply provides a stable power source, and the back-end linear power supply is connected in series to control the linear amplification of the current for output. Based on the control loop of power supply current and tube voltage drop, the stability of the output current has been further improved through temperature compensation measures for key components. Through the modular design of the back-end linear power supply, the volume of the power supply has been reduced and the convenience of operation and maintenance has been improved. The measured results show that the long-term current stability for 8 h reaches 1.3×10−6, and the noise is extremely low.
With the in-depth study of particle accelerator physics experiments, the requirements higher for beam quality have gradually increased. To obtain a magnetic field environment with extremely high stability and extremely low noise, a high-precision DC excitation power supply combining switching mode and linear mode was analyzed and designed. The front-end switching power supply provides a stable power source, and the back-end linear power supply is connected in series to control the linear amplification of the current for output. Based on the control loop of power supply current and tube voltage drop, the stability of the output current has been further improved through temperature compensation measures for key components. Through the modular design of the back-end linear power supply, the volume of the power supply has been reduced and the convenience of operation and maintenance has been improved. The measured results show that the long-term current stability for 8 h reaches 1.3×10−6, and the noise is extremely low.
, Available online , doi: 10.11884/HPLPB202537.250014
Abstract:
Strong electromagnetic pulse can induce nanosecond rising edge pulse conduction disturbance on the cable in the form of field-transmission line coupling, which poses a great threat to the equipment at the end of the cable. For a certain type of relay protection device, the immunity performance is tested first, and then the high-altitude electromagnetic pulse irradiation test under the field-line coupling path is carried out to obtain the coupling characteristics of the device port. The device malfunctions when the common mode current coupled to the signal port reaches 32.45 A and above. At the same time, the pulse current injection test is carried out. When the pulse current injected into the signal port reaches 36.92 A or more, the device malfunctions, further confirming the critical interference threshold of the device port. Through the establishment of the field-line coupling model of the secondary cable in the substation and the signal cable in the protective panel cabinet, the coupling quantity of high-altitude electromagnetic pulse in different scenarios is calculated, and the key points of field-line coupling protection are proposed. The research results can provide reference for the evaluation of anti-interference ability and protection technology of relay protection devices in strong electromagnetic pulse environments.
Strong electromagnetic pulse can induce nanosecond rising edge pulse conduction disturbance on the cable in the form of field-transmission line coupling, which poses a great threat to the equipment at the end of the cable. For a certain type of relay protection device, the immunity performance is tested first, and then the high-altitude electromagnetic pulse irradiation test under the field-line coupling path is carried out to obtain the coupling characteristics of the device port. The device malfunctions when the common mode current coupled to the signal port reaches 32.45 A and above. At the same time, the pulse current injection test is carried out. When the pulse current injected into the signal port reaches 36.92 A or more, the device malfunctions, further confirming the critical interference threshold of the device port. Through the establishment of the field-line coupling model of the secondary cable in the substation and the signal cable in the protective panel cabinet, the coupling quantity of high-altitude electromagnetic pulse in different scenarios is calculated, and the key points of field-line coupling protection are proposed. The research results can provide reference for the evaluation of anti-interference ability and protection technology of relay protection devices in strong electromagnetic pulse environments.
, Available online , doi: 10.11884/HPLPB202537.250093
Abstract:
When a MV triggered gas switch (TGS) is triggered by an electric pulse, a good electrical connection between the trigger generator and the TGS is required to ensure the trigger effect. Additionally a protective method is also necessary to avoid the damage to the trigger generator which feeds back from the MV main pulse after the TGS closes. In this paper, a novel trigger pulse feed and protection method is introduced. The trigger pulse is introduced via a protective resistor, which is placed between the inner and outer cylindrical electrodes of the pulse transmission line. The MV pulse is attenuated because the voltage is resistively divided by the resistor and trigger cable arrangement. Both the complex breakdown processes of the switch and its insulation issues are experimentally studied. The function and the beneficial effects of the protective resistor, installed with an additional inductor, are discussed. Finally, the parameters of these two protective components are set to 500 Ω and 2 μH, under which conditions the switch is demonstrated to operate successfully at 2.6 MV.
When a MV triggered gas switch (TGS) is triggered by an electric pulse, a good electrical connection between the trigger generator and the TGS is required to ensure the trigger effect. Additionally a protective method is also necessary to avoid the damage to the trigger generator which feeds back from the MV main pulse after the TGS closes. In this paper, a novel trigger pulse feed and protection method is introduced. The trigger pulse is introduced via a protective resistor, which is placed between the inner and outer cylindrical electrodes of the pulse transmission line. The MV pulse is attenuated because the voltage is resistively divided by the resistor and trigger cable arrangement. Both the complex breakdown processes of the switch and its insulation issues are experimentally studied. The function and the beneficial effects of the protective resistor, installed with an additional inductor, are discussed. Finally, the parameters of these two protective components are set to 500 Ω and 2 μH, under which conditions the switch is demonstrated to operate successfully at 2.6 MV.
, Available online , doi: 10.11884/HPLPB202537.240280
Abstract:
To improve the vacuum surface flashover performance of insulators, a kind of composite surface structure consisting of micro grooves and molecule self-assembly membrane was proposed and prepared on the surface of alumina vacuum insulators by laser carving, water cleaning and molecule self-assembly. Meanwhile, insulators with only micro grooves or pure molecule membrane were also prepared. The secondary electron emission yield test showed that both the micro groove structure and molecule self-assembly could reduce the secondary electron emission yield of the alumina insulator. Their combination (the composite surface structure) could further reduce the secondary electron emission yield. Correspondingly, the surface flashover voltage test indicated that surface micro groove construction and molecule self-assembly could both improve the surface flashover voltages and their combination could further improve the flashover voltages. The results demonstrate that molecule membrane and the micro grooves in the composite structure can form dual suppression on the development of the vacuum flashover.
To improve the vacuum surface flashover performance of insulators, a kind of composite surface structure consisting of micro grooves and molecule self-assembly membrane was proposed and prepared on the surface of alumina vacuum insulators by laser carving, water cleaning and molecule self-assembly. Meanwhile, insulators with only micro grooves or pure molecule membrane were also prepared. The secondary electron emission yield test showed that both the micro groove structure and molecule self-assembly could reduce the secondary electron emission yield of the alumina insulator. Their combination (the composite surface structure) could further reduce the secondary electron emission yield. Correspondingly, the surface flashover voltage test indicated that surface micro groove construction and molecule self-assembly could both improve the surface flashover voltages and their combination could further improve the flashover voltages. The results demonstrate that molecule membrane and the micro grooves in the composite structure can form dual suppression on the development of the vacuum flashover.
, Available online , doi: 10.11884/HPLPB202537.250042
Abstract:
Under the driving of explosive-emission cathodes, relativistic gyrotrons frequently suffer from virtual cathode phenomena induced by ultrahigh beam currents (＞300 A), where electron beams readily impact the inner conductor surfaces, accompanied by unintended excitations of cyclotron resonance and backward-wave oscillation (BWO) modes. This study systematically investigates the electromagnetic characteristics of an X-band coaxial gyrotron cavity driven by an intense relativistic electron beam (IREB), combining theoretical analysis with three-dimensional particle-in-cell (PIC) simulations. The results demonstrate that stable IREB transmission and TE01 single-mode operation can be achieved through cavity geometry optimization and electron beam parameter matching. The cavity quality factor (Qcav) plays a critical role in suppressing parasitic mode competition: TE21-BWO modes are excited when Qcav＜65, while TE31 cyclotron resonance modes emerge when Qcav＞90. Stable TE01 single-mode oscillation with an output power of 35 MW (voltage: 300 kV, current: 500 A, transverse-to-longitudinal velocity ratio: 1.2) and efficiency of 34.4% are maintained within the Qcav range of 65-90. Further studies reveal that the cavity exhibits significant robustness against electron beam velocity spread (Δβ＜25%), providing critical insights for high-power microwave source design.
Under the driving of explosive-emission cathodes, relativistic gyrotrons frequently suffer from virtual cathode phenomena induced by ultrahigh beam currents (＞300 A), where electron beams readily impact the inner conductor surfaces, accompanied by unintended excitations of cyclotron resonance and backward-wave oscillation (BWO) modes. This study systematically investigates the electromagnetic characteristics of an X-band coaxial gyrotron cavity driven by an intense relativistic electron beam (IREB), combining theoretical analysis with three-dimensional particle-in-cell (PIC) simulations. The results demonstrate that stable IREB transmission and TE01 single-mode operation can be achieved through cavity geometry optimization and electron beam parameter matching. The cavity quality factor (Qcav) plays a critical role in suppressing parasitic mode competition: TE21-BWO modes are excited when Qcav＜65, while TE31 cyclotron resonance modes emerge when Qcav＞90. Stable TE01 single-mode oscillation with an output power of 35 MW (voltage: 300 kV, current: 500 A, transverse-to-longitudinal velocity ratio: 1.2) and efficiency of 34.4% are maintained within the Qcav range of 65-90. Further studies reveal that the cavity exhibits significant robustness against electron beam velocity spread (Δβ＜25%), providing critical insights for high-power microwave source design.
, Available online , doi: 10.11884/HPLPB202537.250032
Abstract:
In this paper, a miniaturized Planar Inverted-F Electromagnetic Protective Antenna is proposed, which achieves adaptive switching between the normal operation mode and the electromagnetic protection mode by loading a U-shaped protective structure on the planar inverted-F antenna. The U-shaped structure is connected to the antenna feed line via PIN diodes. Under normal operation, when the received signal power is below the threshold, the PIN diodes remain in the cutoff state, allowing the antenna to maintain its radiation characteristics without interference from the U-shaped structure. When under high-power microwave attacks, a strong induced electric field is generated across the PIN diodes in the U-shaped structure, causing them to rapidly switch to achieve a low-impedance conduction state. At this point, the U-shaped structure forms a closed loop with the feed line, effectively preventing high-power microwave signals from entering the backend electronic equipment, thereby achieving electromagnetic protection. By optimizing the geometric parameters of the U-shaped structure and the number of loaded diodes, the design maintains its compact size while delivering excellent radiation performance and protection capability. Measurement results show that the antenna achieves a relative bandwidth of 17.2%, with a gain of 2.36 dBi at the center frequency of 1.57 GHz. Simulation results demonstrate a protection level of 16.4 dB in the electromagnetic protection state. The radiator’s electrical dimension is only 0.25λ×0.06λ, realizing a miniaturized design for the electromagnetic protective antenna.
In this paper, a miniaturized Planar Inverted-F Electromagnetic Protective Antenna is proposed, which achieves adaptive switching between the normal operation mode and the electromagnetic protection mode by loading a U-shaped protective structure on the planar inverted-F antenna. The U-shaped structure is connected to the antenna feed line via PIN diodes. Under normal operation, when the received signal power is below the threshold, the PIN diodes remain in the cutoff state, allowing the antenna to maintain its radiation characteristics without interference from the U-shaped structure. When under high-power microwave attacks, a strong induced electric field is generated across the PIN diodes in the U-shaped structure, causing them to rapidly switch to achieve a low-impedance conduction state. At this point, the U-shaped structure forms a closed loop with the feed line, effectively preventing high-power microwave signals from entering the backend electronic equipment, thereby achieving electromagnetic protection. By optimizing the geometric parameters of the U-shaped structure and the number of loaded diodes, the design maintains its compact size while delivering excellent radiation performance and protection capability. Measurement results show that the antenna achieves a relative bandwidth of 17.2%, with a gain of 2.36 dBi at the center frequency of 1.57 GHz. Simulation results demonstrate a protection level of 16.4 dB in the electromagnetic protection state. The radiator’s electrical dimension is only 0.25λ×0.06λ, realizing a miniaturized design for the electromagnetic protective antenna.
, Available online , doi: 10.11884/HPLPB202537.240349
Abstract:
To improve the performance of waveform digital readout systems based on Analog to Digital Converter (ADC) technology, this paper proposes a multi-channel mismatch error estimation calibration method. It uses two domestically produced high-speed ADCs to form a Time-interleaved A/D Conversion (TIADC) system, and the estimation of channel mismatch error (Gain, Time-skew and Offset) can be obtained by integrating particle swarm optimization (PSO) algorithm and gradient descent (GD) method. Meanwhile, it uses filter equations and Kaiser window truncation to obtain compensation calibration filter coefficient values. This compensation method can be directly implemented on the TIADC hardware platform using Field-Programmable Gate Array(FPGA) as the central processing unit. Moreover, this algorithm can achieve online reconstruction of sampling system data. The experimental results show that the algorithm can effectively compensate for channel mismatch errors, and using the behavior level simulation of Vivado development software, the spurious free dynamic range (SFDR) is increased from 32.1 dBFS to 53.1 dBFS, the SFDR is improved to 60.8 dBFS during hardware platform testing. This signal reconstruction method is also easy to implement in hardware systems and is not limited by the number of channels.
To improve the performance of waveform digital readout systems based on Analog to Digital Converter (ADC) technology, this paper proposes a multi-channel mismatch error estimation calibration method. It uses two domestically produced high-speed ADCs to form a Time-interleaved A/D Conversion (TIADC) system, and the estimation of channel mismatch error (Gain, Time-skew and Offset) can be obtained by integrating particle swarm optimization (PSO) algorithm and gradient descent (GD) method. Meanwhile, it uses filter equations and Kaiser window truncation to obtain compensation calibration filter coefficient values. This compensation method can be directly implemented on the TIADC hardware platform using Field-Programmable Gate Array(FPGA) as the central processing unit. Moreover, this algorithm can achieve online reconstruction of sampling system data. The experimental results show that the algorithm can effectively compensate for channel mismatch errors, and using the behavior level simulation of Vivado development software, the spurious free dynamic range (SFDR) is increased from 32.1 dBFS to 53.1 dBFS, the SFDR is improved to 60.8 dBFS during hardware platform testing. This signal reconstruction method is also easy to implement in hardware systems and is not limited by the number of channels.
, Available online , doi: 10.11884/HPLPB202537.240397
Abstract:
The deterministic calculation method based on multi-group cross section has always been an important approach in the design of nuclear reactors. The accuracy of multi-group cross section directly affects the precision of nuclear reactor physics calculations. To generate high-precision cross section data for fast reactors, North China Electric Power University developed the high-precision cross section processing code MGGC2.0. This paper conducts benchmark verification and validation of the code. The infinite homogeneous mixed media UO2, MOX, and U-TRU-Zr fuels are calculated based on the ENDF/B-VII.1 library, and the macroscopic cross sections generated by MGGC2.0 are compared with those produced by MCNP to verify the accuracy of the program in generating multi-group cross sections. The relative deviation of the macroscopic multi-group total cross section from the reference solution of MCNP is generally within 5%. Subsequently, calculations are performed for the Russian fast reactor BFS97-1 experiment, and a homogenization method of the fuel few-group cross section for various fuel arrangements is proposed. The collision probability method in MGGC2.0 is used to calculate the few-group cross section data for the fuel, and the DIF3D program is employed for core calculations. Additionally, this study compares the results obtained using different cross section homogenization methods. The research findings indicate that for BFS97-1, if the cross sections generated directly by critical search are used, the absolute deviation of the keff calculated by DIF3D from that calculated by MCNP is 2.541×10−2. This paper improves the calculation method of axial fuel inhomogeneity, reducing the deviation to below 5.0×10−4. The deviations between the calculated results for BFS97-1, BFS97-2, BFS97-5, and BFS97-6 and the MCNP results are all within3.0×10−3, validating the high accuracy of the code in generating multi-group and few-group cross section, which meets the requirements of engineering design.
The deterministic calculation method based on multi-group cross section has always been an important approach in the design of nuclear reactors. The accuracy of multi-group cross section directly affects the precision of nuclear reactor physics calculations. To generate high-precision cross section data for fast reactors, North China Electric Power University developed the high-precision cross section processing code MGGC2.0. This paper conducts benchmark verification and validation of the code. The infinite homogeneous mixed media UO2, MOX, and U-TRU-Zr fuels are calculated based on the ENDF/B-VII.1 library, and the macroscopic cross sections generated by MGGC2.0 are compared with those produced by MCNP to verify the accuracy of the program in generating multi-group cross sections. The relative deviation of the macroscopic multi-group total cross section from the reference solution of MCNP is generally within 5%. Subsequently, calculations are performed for the Russian fast reactor BFS97-1 experiment, and a homogenization method of the fuel few-group cross section for various fuel arrangements is proposed. The collision probability method in MGGC2.0 is used to calculate the few-group cross section data for the fuel, and the DIF3D program is employed for core calculations. Additionally, this study compares the results obtained using different cross section homogenization methods. The research findings indicate that for BFS97-1, if the cross sections generated directly by critical search are used, the absolute deviation of the keff calculated by DIF3D from that calculated by MCNP is 2.541×10−2. This paper improves the calculation method of axial fuel inhomogeneity, reducing the deviation to below 5.0×10−4. The deviations between the calculated results for BFS97-1, BFS97-2, BFS97-5, and BFS97-6 and the MCNP results are all within3.0×10−3, validating the high accuracy of the code in generating multi-group and few-group cross section, which meets the requirements of engineering design.
, Available online , doi: 10.11884/HPLPB202537.250056
Abstract:
To investigate the effects of contact and axial power on the thermodynamic performance of the heat pipe cooled reactor core, a thermal-mechanical coupling program was developed based on the FEniCS platform. The program uses a simplified method to solve 2D and 3D contact pressure, primarily including gap heat transfer, linear elastic mechanics, and multidimensional contact pressure solution models. Taking the MegaPower reactor as the subject, the study first validated the accuracy of the program using ANSYS, and then a thermal-mechanical simulation of the core was performed to analyze temperature and Mises stress fields. The results indicate that when considering contact, the peak temperature of the fuel pin significantly decreases and the Mises stress decreases slightly; the peak temperature of the monolith changes little, but the Mises stress increases markedly. The axial power mainly affects the Mises stress of the fuel pin, while the Mises stress of the monolith is primarily influenced by contact pressure.
To investigate the effects of contact and axial power on the thermodynamic performance of the heat pipe cooled reactor core, a thermal-mechanical coupling program was developed based on the FEniCS platform. The program uses a simplified method to solve 2D and 3D contact pressure, primarily including gap heat transfer, linear elastic mechanics, and multidimensional contact pressure solution models. Taking the MegaPower reactor as the subject, the study first validated the accuracy of the program using ANSYS, and then a thermal-mechanical simulation of the core was performed to analyze temperature and Mises stress fields. The results indicate that when considering contact, the peak temperature of the fuel pin significantly decreases and the Mises stress decreases slightly; the peak temperature of the monolith changes little, but the Mises stress increases markedly. The axial power mainly affects the Mises stress of the fuel pin, while the Mises stress of the monolith is primarily influenced by contact pressure.
, Available online , doi: 10.11884/HPLPB202537.250116
Abstract:
Improving the wide-temperature operation ability of fiber lasers can effectively enhance the environmental adaptability and operation reliability of fiber lasers under extreme high- and low-temperature conditions. This ensure their stable output under complex working conditions, and provides support for technological innovation and industrial upgrading in related fields. Recently, the National University of Defense Technology achieved a near-single-mode all-fiber laser oscillator that can operate stably within the temperature range of −50 to 50 ℃ by directly pumping with fiber-coupled semiconductor lasers. The output power reached 2 kW, which is the highest output power level of fiber lasers operating in such a wide temperature range reported publicly so far.
Improving the wide-temperature operation ability of fiber lasers can effectively enhance the environmental adaptability and operation reliability of fiber lasers under extreme high- and low-temperature conditions. This ensure their stable output under complex working conditions, and provides support for technological innovation and industrial upgrading in related fields. Recently, the National University of Defense Technology achieved a near-single-mode all-fiber laser oscillator that can operate stably within the temperature range of −50 to 50 ℃ by directly pumping with fiber-coupled semiconductor lasers. The output power reached 2 kW, which is the highest output power level of fiber lasers operating in such a wide temperature range reported publicly so far.
, Available online , doi: 10.11884/HPLPB202537.240413
Abstract:
In high-energy laser systems, the performance parameters of large-aperture sampling optics determine the accuracy of beam testing and evaluation, as well as the precision of overall system performance control. This paper focuses on the performance testing requirements of sampling optics with high-reflectivity (HR) on the front surface and anti-reflectivity (AR) on the back surface. Utilizing the cavity-ring-down (CRD)-based reflectivity uniformity testing of large-aperture sampling optics, the reflectivity distribution, optical loss, and high-resolution scanning imaging of defects of sampling optics are obtained by scanning measuring the incident light from both the reflective film surface and the anti-reflective film surface, respectively. Furthermore, by comparing and analyzing the defect distribution maps, the classification of defects in the reflective film, transmissive film, and substrate of the sampling optics is achieved. Finally, by establishing a dual channel CRD system, the residual reflectance distribution of anti-reflective film and the types of defects in the transmissive film were obtained. The testing and analysis method proposed in this paper provides a systematic and comprehensive characterization tool for the performance evaluation and defect analysis of sampling optics.
In high-energy laser systems, the performance parameters of large-aperture sampling optics determine the accuracy of beam testing and evaluation, as well as the precision of overall system performance control. This paper focuses on the performance testing requirements of sampling optics with high-reflectivity (HR) on the front surface and anti-reflectivity (AR) on the back surface. Utilizing the cavity-ring-down (CRD)-based reflectivity uniformity testing of large-aperture sampling optics, the reflectivity distribution, optical loss, and high-resolution scanning imaging of defects of sampling optics are obtained by scanning measuring the incident light from both the reflective film surface and the anti-reflective film surface, respectively. Furthermore, by comparing and analyzing the defect distribution maps, the classification of defects in the reflective film, transmissive film, and substrate of the sampling optics is achieved. Finally, by establishing a dual channel CRD system, the residual reflectance distribution of anti-reflective film and the types of defects in the transmissive film were obtained. The testing and analysis method proposed in this paper provides a systematic and comprehensive characterization tool for the performance evaluation and defect analysis of sampling optics.
, Available online , doi: 10.11884/HPLPB202537.250002
Abstract:
In ultrafast high-power laser systems, achromatic lens groups are typically used to replace standard beam expanders to eliminate spatio-temporal coupling (STC) distortions caused by chromatic aberrations. However, alignment errors in these achromatic lens groups can introduce new STC distortions, reducing far-field power density and compromising the desired correction. This paper quantitatively analyzes the STC distortions induced by three types of alignment errors using a broad-spectrum pulse laser transmission model and a thick lens equivalent phase screen model. The impact of these errors on far-field focusing power density is evaluated, and permissible error ranges for each type are established.
In ultrafast high-power laser systems, achromatic lens groups are typically used to replace standard beam expanders to eliminate spatio-temporal coupling (STC) distortions caused by chromatic aberrations. However, alignment errors in these achromatic lens groups can introduce new STC distortions, reducing far-field power density and compromising the desired correction. This paper quantitatively analyzes the STC distortions induced by three types of alignment errors using a broad-spectrum pulse laser transmission model and a thick lens equivalent phase screen model. The impact of these errors on far-field focusing power density is evaluated, and permissible error ranges for each type are established.
, Available online , doi: 10.11884/HPLPB202537.240401
Abstract:
This paper introduces the working principle, composition and configuration of a miniaturized high-throughput neutron source system. It systematically introduces the piezoelectric pulse power source technology, nuclear reaction design technology, spherical electromagnetic field generation technology, particle proximity acceleration technology, particle polarization and resonance collision technology required for the development of this neutron source system. A complete neutron source physical system was developed and tested for energy spectrum and flux. The expected physical phenomena were observed in the experiments, and the occurrence of nuclear reactions was proved by online and offline neutron measurement methods, and the test results showed that the neutron radiation flux of the new miniature neutron source with a diameter of 2 cm and a length of 4 cm reached the level of 1010 n/(cm2·s), which belongs to strong neutron radiation source.
This paper introduces the working principle, composition and configuration of a miniaturized high-throughput neutron source system. It systematically introduces the piezoelectric pulse power source technology, nuclear reaction design technology, spherical electromagnetic field generation technology, particle proximity acceleration technology, particle polarization and resonance collision technology required for the development of this neutron source system. A complete neutron source physical system was developed and tested for energy spectrum and flux. The expected physical phenomena were observed in the experiments, and the occurrence of nuclear reactions was proved by online and offline neutron measurement methods, and the test results showed that the neutron radiation flux of the new miniature neutron source with a diameter of 2 cm and a length of 4 cm reached the level of 1010 n/(cm2·s), which belongs to strong neutron radiation source.
, Available online , doi: 10.11884/HPLPB202537.240400
Abstract:
To effectively solve the problem of strong electromagnetic pulse power required to drive particle reactions, a new pulse power synchronous amplification technology based on hydrogen plasma loading and wave-particle resonance mechanism is studied on the basis of piezoelectric ceramic stack pulse source. The amplification mechanism is as follows: first, the energy of hydrogen molecule bonding orbitals is lower than that of antibonding orbitals, and internal energy will be released during the ionization process to promote the efficient occurrence of the ionization process driven by pulse power; Second, after the ionization of hydrogen atoms, the electromagnetic field and electrons undergo wave-particle resonance, and the electron energy is synchronously converted into electromagnetic field energy. After the amplification of wave-particle resonance, a stronger electromagnetic pulse is obtained, which can form a spherical electromagnetic field when applied to the spiral electrode, and has an extremely high acceleration gradient, which can accelerate a large number of protons produced after efficient ionization of hydrogen atoms. The above theory is effectively proved through experimental tests and simulation analysis, and this research is expected to lay a foundation for a miniaturized and low-cost proton generator driven by strong electromagnetic pulses.
To effectively solve the problem of strong electromagnetic pulse power required to drive particle reactions, a new pulse power synchronous amplification technology based on hydrogen plasma loading and wave-particle resonance mechanism is studied on the basis of piezoelectric ceramic stack pulse source. The amplification mechanism is as follows: first, the energy of hydrogen molecule bonding orbitals is lower than that of antibonding orbitals, and internal energy will be released during the ionization process to promote the efficient occurrence of the ionization process driven by pulse power; Second, after the ionization of hydrogen atoms, the electromagnetic field and electrons undergo wave-particle resonance, and the electron energy is synchronously converted into electromagnetic field energy. After the amplification of wave-particle resonance, a stronger electromagnetic pulse is obtained, which can form a spherical electromagnetic field when applied to the spiral electrode, and has an extremely high acceleration gradient, which can accelerate a large number of protons produced after efficient ionization of hydrogen atoms. The above theory is effectively proved through experimental tests and simulation analysis, and this research is expected to lay a foundation for a miniaturized and low-cost proton generator driven by strong electromagnetic pulses.
, Available online , doi: 10.11884/HPLPB202537.240163
Abstract:
The quantitative study of combat effectiveness index is crucial for the informatization construction of the armed forces. To solve the problems of limits of quantitative research, low method accuracy, and weak robustness in the study of combat effectiveness index, and to break through the limitations of dominating complex rules, multivariate mathematical models, and strong coupling of influencing factors in the combat effectiveness index function, inspired by the mathematical analysis methods of rules in fuzzy logic theory, we proposed a local approximation based method for fitting combat effectiveness index function. Combining the powerful self-learning and self-deduction capabilities of neural networks, we constructed a corresponding quantitative calculation model based on radial basis function (RBF). Simulation comparative experiments show that the proposed method has an error rate of about 2% and 6% lower than the current best performing method using global approximation, and exhibits stronger robustness. Our method has strong practicality, can be migrated to other military fields, and has good engineering application prospects.
The quantitative study of combat effectiveness index is crucial for the informatization construction of the armed forces. To solve the problems of limits of quantitative research, low method accuracy, and weak robustness in the study of combat effectiveness index, and to break through the limitations of dominating complex rules, multivariate mathematical models, and strong coupling of influencing factors in the combat effectiveness index function, inspired by the mathematical analysis methods of rules in fuzzy logic theory, we proposed a local approximation based method for fitting combat effectiveness index function. Combining the powerful self-learning and self-deduction capabilities of neural networks, we constructed a corresponding quantitative calculation model based on radial basis function (RBF). Simulation comparative experiments show that the proposed method has an error rate of about 2% and 6% lower than the current best performing method using global approximation, and exhibits stronger robustness. Our method has strong practicality, can be migrated to other military fields, and has good engineering application prospects.
