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, Available online , doi: 10.11884/HPLPB202537.250024
Abstract:
Background Purpose Methods Results Conclusions
High-repetition-rate electron accelerators face beam instabilities induced by wake fields from beam-vacuum chamber interactions. Geometric discontinuities at ubiquitous Con Flat (CF) knife-edge flange connections are a dominant source of beam-induced impedance in all-metal vacuum chambers.
To mitigate this impedance, this paper designs an RF-shielded flange-gasket connection structure achieving a smooth post-tightening transition at the interface, thereby minimizing impedance.
1. Electromagnetic Simulation: 3D simulations (CST) analyzed impedance effects of radial step heights and axial gaps at the transition, establishing allowable parameter ranges. 2. Deformation Simulation: ANSYS simulations modeled the shielded flange-copper gasket assembly to preliminarily determine inner diameter specifications for various gasket models. 3. Vacuum Sealing Tests: Verified ultra-high vacuum integrity under applied tightening torque. 4. Transition Geometry Testing: Measured the achieved radial step and axial gap post-tightening to define optimal copper gasket dimensions and tightening torque. 5. Comparative Simulation: CST simulations compared power loss and impedance for smooth chambers, standard flange-gasket transitions, and the proposed shielded transition.
1. Electromagnetic simulations defined critical tolerance ranges for radial step and axial gap. 2. Deformation simulations provided initial gasket inner diameter specifications. 3. Vacuum tests confirmed effective sealing at a tightening torque≥6 N·m. 4. Transition testing established the optimal tightening torque and key copper gasket dimensions ensuring minimal geometric discontinuity. 5. Comparative simulations demonstrated that the RF-shielded flange-gasket transition significantly reduces power loss and impedance compared to a standard CF transition, achieving performance close to that of a smooth vacuum chamber.
The designed RF-shielded flange-gasket connection structure effectively minimizes geometric discontinuity at the joint. Through combined electromagnetic, mechanical, and vacuum testing, critical parameters (radial step, axial gap, gasket dimensions, tightening torque≥6 N · m) were optimized. Electromagnetic verification confirms this design provides effective impedance shielding, offering a solution to mitigate wake-field-induced instabilities at flange connections in high-energy accelerators.
, Available online , doi: 10.11884/HPLPB202537.250055
Abstract:
Background Purpose Methods Results Conclusions
With the increasing requirement of beam stability in particle accelerators, the accuracy of engineering control network is required to be higher.
This study aims to elaborate the specific observation scheme for large-scale tunnel control network, and introduce the control network layout, measurement mode and data processing.
In this paper, taking the booster of High Energy Photon Source (HEPS) with the circumference of 454 m as an example, aiming at the disadvantages of narrow space in the tunnel, the control network layout scheme and measurement method based on laser tracker precision measurement are proposed. At the same time, in the face of the problem of data validity detection of multiple stations and close points in the measurement process, the quality control method of adjacent single station fitting and multi-station fitting is proposed, and the point fitting error RMS is better than 0.1 mm.
Finally, the absolute point error RMS of radial, tangential and elevation coordinate components of the control network reaches 0.2 mm, which meets the installation accuracy requirements of the equipment. At the same time, in order to monitor the stability of the enhancer after the initial construction, two phases of the enhancer control network were observed in one year. The measurement results show that the deformation of the booster tunnel is about 10 mm in one year. The specific manifestation is that the tunnel foundation expands outward in the three areas of southeast, northwest and southwest.
Overall, the point accuracy of the three directions of the control network is different. The correctness and reliability of the results of the control network can be ensured through multiple control network measurements and data processing and analysis, which provides a reference for other synchrotron radiation light source.
, Available online , doi: 10.11884/HPLPB202537.250106
Abstract:
Background Purpose Methods Results Conclusions
In the Hard X-ray Free Electron Laser (SHINE), the normal-conducting L-band buncher plays a critical role in the compression of electron bunches, significantly improving beam quality meeting the stringent injection requirements of low emittance and low energy spread.
Due to its 2-cell structure, a dedicated digital low-level RF control system was developed.
This system, based on an architecture comprising FPGA and RF front-end boards, and adopts I/Q demodulation techniques. It incorporates amplitude and phase feedback, frequency tuning, and multi-motor coordinated for field flatness control.
During 10 kW continuous-wave (CW) operation the amplitude stability (peak-to-peak) improved from ±0.17% in open-loop to within ±0.03% under closed-loop, while the phase stability (peak-to-peak) was controlled within ±0.05°, and field flatness was maintained within ±2%, fully meeting design specifications. Additionally, a radio-frequency (RF) power calibration method based on ADC acquisition of LLRF was proposed.
Experimental results showed calibration error within ±2% when compared with power meter, demonstrating this method’s reliability as an alternative solution for RF power calibration.
, Available online , doi: 10.11884/HPLPB202537.250022
Abstract:
Background Purpose Methods Results Conclusions
Free electron lasers have emerged as significant advanced light sources owing to their unique advantages, including high power, excellent coherence, and wavelength tunability. Given that the peak and average brightness of an FEL depend on the quality of the electron beam generated by its injector, the optimization of the beam injector constitutes a key technical challenge in FEL development. The Hefei Infrared Free Electron Laser facility, a state-of-the-art, oscillator-type user facility providing continuously tunable mid-to-far-infrared radiation.
The injector structure of Hefei Infrared Free Electron Laser is optimized to obtain electron beams with lower emittance, shorter beam length, smaller energy spread and higher peak current intensity, so as to improve the performance of driving infrared free electron laser light source.
The optimization research is carried out by combining beam dynamics simulation with numerical simulation. Based on the previous optimization of the electron gun’s grid structure, the improved design is carried out. A new 12th sub-harmonic buncher is added to the front stage of the existing 6th sub-harmonic buncher, and then the beam is bunched and accelerated by using the appropriate traveling-wave buncher. Key parameters including the beam injection phase and the phase velocity variation in the traveling-wave buncher’s tapered section are systematically scanned to achieve 100% bunch capture efficiency and accelerate the electron beam to near-light-speed energy during the bunching stage.
Finally, the beam energy is increased to 64 MeV, and the root mean square length of the whole bunch reaches 8.5 ps. The high-energy scattered electrons are filtered out, and the electron beams scattered by ±1% bunch energy are counted. The optimized beam core achieves a root-mean-square longitudinal bunch length of 3.1 ps with an energy spread below 0.23 MeV, while the normalized transverse emittance is reduced to 9.8 mm·mrad. At the same time, the peak current intensity reaches 270 A, which is 2.7 times that of the original optimization results.
The simulation shows that the longitudinal length, energy dispersion and emittance of the core region of the bunch are significantly reduced after optimization, and the peak current intensity is greatly improved. Compared with the original structure, this scheme has significant advantages in the key performance of free electron laser, which has important engineering value for light source upgrading. The optimization method can be extended to the design of other light source injectors.
, Available online , doi: 10.11884/HPLPB202537.250051
Abstract:
Background Purpose Methods Results Conclusions
Single-phase AC-input low-ripple DC regulated power supplies are critical for sensitive applications. However, conventional designs often suffer from complex power circuit configurations, increasing cost and size while potentially compromising reliability. Achieving simultaneously low output voltage ripple, high steady-state accuracy, and wide output voltage adjustability remains a significant challenge in power electronics.
This study aims to overcome the limitations of existing topologies by proposing a novel single-phase AC-input low-ripple adjustable DC regulated power supply circuit. Furthermore, it develops a dedicated advanced control strategy to meet stringent low-ripple and high-stability performance requirements.
The fundamental principles of the proposed topology were analyzed, and its mathematical model established to characterize voltage transmission. A composite control scheme integrating reference output voltage amplitude self-compensation using improved Iterative Learning Control (ILC), and a dual-loop Proportional Complex Integral (PCI) control structure, was designed for precise low-ripple regulation and stability. Effectiveness was validated via simulation and experimental testing on a prototype.
Validation confirmed successful operation. Comparative analysis demonstrated the topology's advantages: simpler/compact structure, wide adjustable output voltage, significantly reduced ripple, and improved steady-state accuracy. The control strategy effectively ensured stability and met performance targets.
The combined novel topology and advanced control provide a viable solution for high-quality single-phase AC-input adjustable DC supplies.
, Available online , doi: 10.11884/HPLPB202537.250012
Abstract:
Background Purpose Methods Results Conclusions
When the primary system of nuclear reactors experiences overpressure, the overpressure discharge system can be utilized to release the high-temperature and high-pressure fluid through the safety valve and downstream pipelines to achieve pressure reduction.
However, the rapid opening of the safety valve can lead to a violent release of the fluid, which may impose severe transient load impacts on the pipelines and the pool.
Analyzing the typical characteristics and influencing factors of the emission phenomenon can provide references for system operation and design. A systematic analysis model including the pressure vessel, pipelines, and water pool was established. The model was finely divided, with the length of the pipeline control body not exceeding 0.3 m, and the water pool was composed of multiple control bodies. The load solution is carried out using the momentum balance method, and calculation results are compared with the EPRI/CE international test. The established analysis model can quickly obtain the thermal response and load response during the discharge process.
The results show that during the overpressure discharge process, there is a water seal at the valve inlet and the opening time reduction will cause the peak load on the pipelines and the water pool to increase.
A decrease in the nozzle immersion depth or an increase in the water pool cross-sectional area will result in a reduction in the peak load at the water pool location.
, Available online , doi: 10.11884/HPLPB202537.250061
Abstract:
Background Purpose Methods Results Conclusions
Tritium production pathways are well-established for large pressurized water reactors (PWRs). Integrated small reactors (ISRs), however, operate without soluble boron reactivity control and use no chemical additives (e.g., lithium hydroxide) for pH adjustment, necessitating dedicated analysis of their tritium sources.
This study aims to identify tritium production pathways in ISRs, establish a computational model for quantifying tritium source terms, and propose design optimizations to minimize tritium generation.
A theoretical model was established by solving differential equations for tritium production and removal based on identified neutron activation reaction mechanisms. Key parameters included neutron flux and nuclear cross-sections derived from Monte Carlo simulations of the ISR core. Validation was performed against normalized operational tritium release data from boiling water reactors (BWRs) with analogous B4C control rods and Sb-Be neutron sources, considering thermal power and load factors.
The annual tritium production in ISR primary coolant is 1.81 TBq. The primary contributors are neutron-activated products from Sb-Be and B4C material, accounting for 46% and 51% of the total production, respectively. Analysis of tritium discharge data from operational BWRs validates the conservatism of the theoretical results.
Optimizing secondary neutron sources (canceling Sb-Be or using double encapsulated cladding) and replacing B4C control rods with non-tritigenic absorbers (e.g., Ag-In-Cd or hafnium) could reduce ISR tritium production significantly. These measures are technically feasible based on PWRs operational experience and are recommended for ISR design enhancements. Future work will refine release fractions of control rods using plant-specific operational data.
, Available online , doi: 10.11884/HPLPB202537.250009
Abstract:
[ Background] Shutdown dose rate (SDR) analysis plays a critical role in ensuring radiation safety during reactor maintenance, transportation, and decommissioning. Traditional methods like the direct one-step (D1S) method and the rigorous two-step (R2S) method face limitations in accuracy and implementation, especially for compact and complex geometries such as vehicle-mounted micro-nuclear power systems. [ Purpose ] This study aims to develop and validate a cell-in-mesh-based R2S method for SDR calculations, with enhanced sampling efficiency and spatial resolution. The goal is to enable accurate prediction of post-shutdown radiation fields for both benchmarking and practical reactor applications. [Methods ] An improved R2S methodology was implemented by integrating nested cell-in-mesh geometry with a Monte Carlo (MC) transport framework. Photon source sampling was optimized using bounding box division and local mesh-based distribution sampling. The method was validated using the ITER shutdown dose rate benchmark and applied to the Megapower microreactor model, which employs HALEU fuel, heat pipe cooling, and composite shielding. [ Results ] The developed method produced SDR distributions with statistical deviations below 2% and matched international benchmark results within 4% deviation. In the Megapower case, the highest dose rate (16.3 mSv/h) at a radial location 30 cm occurred near the heat pipe outlet, primarily due to activated structural materials and neutron streaming along the heat pipe path. [ Conclusions ] The cell-in-mesh-based R2S method improves the accuracy and resolution of SDR calculations without significantly increasing computational cost. It is suitable for advanced shielding analysis of compact nuclear systems and provides a reliable tool for guiding safety design, maintenance planning, and decommissioning strategies.
[ Background] Shutdown dose rate (SDR) analysis plays a critical role in ensuring radiation safety during reactor maintenance, transportation, and decommissioning. Traditional methods like the direct one-step (D1S) method and the rigorous two-step (R2S) method face limitations in accuracy and implementation, especially for compact and complex geometries such as vehicle-mounted micro-nuclear power systems. [ Purpose ] This study aims to develop and validate a cell-in-mesh-based R2S method for SDR calculations, with enhanced sampling efficiency and spatial resolution. The goal is to enable accurate prediction of post-shutdown radiation fields for both benchmarking and practical reactor applications. [Methods ] An improved R2S methodology was implemented by integrating nested cell-in-mesh geometry with a Monte Carlo (MC) transport framework. Photon source sampling was optimized using bounding box division and local mesh-based distribution sampling. The method was validated using the ITER shutdown dose rate benchmark and applied to the Megapower microreactor model, which employs HALEU fuel, heat pipe cooling, and composite shielding. [ Results ] The developed method produced SDR distributions with statistical deviations below 2% and matched international benchmark results within 4% deviation. In the Megapower case, the highest dose rate (16.3 mSv/h) at a radial location 30 cm occurred near the heat pipe outlet, primarily due to activated structural materials and neutron streaming along the heat pipe path. [ Conclusions ] The cell-in-mesh-based R2S method improves the accuracy and resolution of SDR calculations without significantly increasing computational cost. It is suitable for advanced shielding analysis of compact nuclear systems and provides a reliable tool for guiding safety design, maintenance planning, and decommissioning strategies.
, Available online , doi: 10.11884/HPLPB202537.240438
Abstract:
In this paper, view factors are crucial for radiative heat transfer calculation in high-temperature pebble beds. Traditional numerical calculation of view factors demands complex integration, and different formulas are needed for various geometries, leading to high computational complexity. To address this issue, we proposed a view factors model based on ray tracing and combined with particle radiation characteristics. This model eliminates the need for discrete analysis in particle modeling; it only requires particle coordinates and radii for computation. When comparing the results of ray tracing and the numerical method for tangent particles, we found that when the optical density reaches a certain value, the relative error between the two results is within 1%. particle-particle radiation mainly concentrates along the center line, and its intensity decreases in all directions following a cosine function. When we analyzed a single particle from the randomly accumulated pebble bed particles, we determined that the radiation range was mainly within twice the diameter. This was accompanied by a cumulative angular coefficient exceeding 0.98 and the number of particles is within 100. When examining the radiation range within three times the diameter of the particles, we discovered that when the cumulative angular coefficient surpassed 0.99. This paper presents a simpler method for calculating the view factor of complex pebble beds, providing technical support for analyzing the heat radiation transfer characteristics in high-temperature pebble beds.
In this paper, view factors are crucial for radiative heat transfer calculation in high-temperature pebble beds. Traditional numerical calculation of view factors demands complex integration, and different formulas are needed for various geometries, leading to high computational complexity. To address this issue, we proposed a view factors model based on ray tracing and combined with particle radiation characteristics. This model eliminates the need for discrete analysis in particle modeling; it only requires particle coordinates and radii for computation. When comparing the results of ray tracing and the numerical method for tangent particles, we found that when the optical density reaches a certain value, the relative error between the two results is within 1%. particle-particle radiation mainly concentrates along the center line, and its intensity decreases in all directions following a cosine function. When we analyzed a single particle from the randomly accumulated pebble bed particles, we determined that the radiation range was mainly within twice the diameter. This was accompanied by a cumulative angular coefficient exceeding 0.98 and the number of particles is within 100. When examining the radiation range within three times the diameter of the particles, we discovered that when the cumulative angular coefficient surpassed 0.99. This paper presents a simpler method for calculating the view factor of complex pebble beds, providing technical support for analyzing the heat radiation transfer characteristics in high-temperature pebble beds.
Effects of electromagnetic pulse and single event effect on electrical characteristics of SOI MOSFET
, Available online , doi: 10.11884/HPLPB202537.250047
Abstract:
Background Purpose Methods Results Conclusions
In space environments, electronic systems are vulnerable to various adverse effects, including electromagnetic pulses (EMP) and particle radiation, which can significantly degrade device performance and reliability. Silicon-On-Insulator (SOI) MOSFETs are widely used in aerospace applications due to their excellent electrical characteristics, but their response to combined radiation effects needs further investigation.
This study aims to analyze the effects of electromagnetic pulses and heavy-ion induced single-particle events on the electrical characteristics of short-channel SOI MOSFETs. It also explores the synergistic impact when both effects occur simultaneously, providing insights for improving device robustness in harsh space conditions.
A two-dimensional TCAD-based numerical model of short-channel SOI MOSFETs was developed, incorporating impact ionization, carrier generation and recombination, heat transfer, and thermodynamic effects. Electromagnetic pulses were modeled as transient voltage pulses with varying amplitudes, while heavy-ion effects were simulated through charge deposition profiles characterized by LET parameters. The influence of gate voltage, channel length, and LET on device behavior was systematically studied.
Simulation results indicate that EMP-induced voltage transients can cause avalanche breakdown in the drain PN junction, with breakdown voltage decreasing as gate bias increases or channel length shortens. The internal electric field, current density, and device temperature intensify during breakdown. Heavy-ion irradiation generates electron-hole pairs, causing transient increases in drain current, which lower the avalanche breakdown threshold when combined with EMP. Higher LET values further exacerbate device degradation by increasing ionization effects and reducing breakdown voltages. The combined effects produce more severe electrical deterioration compared to single effects.
The research demonstrates that both EMP and heavy-ion irradiation can markedly weaken the electrical stability of short-channel SOI MOSFETs. These findings underscore the importance of designing radiation-hardened devices for space applications. The study provides a theoretical basis for future investigations into the synergistic effects of radiation phenomena on power semiconductor devices.
, Available online , doi: 10.11884/HPLPB202537.250151
Abstract:
Background Purpose Methods Results Conclusions
In the design process of microwave absorbing structures, due to the larger wavelength of low-frequency electromagnetic waves, the thickness of the corresponding absorbing body will also increase. Therefore, achieving low-frequency broadband absorption in the microwave band with a thin thickness is a challenge.
To address the technical bottleneck of limited bandwidth in thin microwave absorbing materials at low frequenciesthis study proposes a new absorbing body design scheme based on a double-layer magnetic medium and mortise structure, focusing on breaking through the constraint relationship between material thickness and absorption bandwidth to achieve efficient absorption of electromagnetic waves in the L/S frequency bands.
The metamaterial is constructed with a double-layer structure using magnetic material, combined with surface periodically arranged mortise-type metal resonant units, and utilizes the synergistic effect of magnetic loss and structural resonance to enhance electromagnetic energy dissipation.
Simulation results show that within the working frequency band, there are two absorption peaks at f1=1.36 GHz and f2=2.29 GHz, and the absorption rate exceeds 90% in the 1.16-2.82 GHz frequency band, effectively covering the L band and extending to part of the S band. Under thin-layer conditions, it achieves a wideband absorption of 1.66 GHz, resolving the inherent contradiction between thickness and bandwidth of low-frequency absorbing materials.
The novel metamaterial absorber based on double magnetic media and mortise structure can provide a feasible solution for the engineering application of the next-generation thin broadband absorbing bodies.
, Available online , doi: 10.11884/HPLPB202537.250133
Abstract:
Optical scattering characteristics are crucial features of space targets and play a vital role in target recognition and detection systems. Traditional methods are limited in simulating optical scattering properties -which only provide optical cross-section (OCS), scattering characteristics, or synthetic target images. To address the above limitations and meet requirements of rendering spatial target, this paper conducts a comprehensive study on the computational modeling of optical scattering characteristics for space targets. A systematic workflow is proposed, along with formulas for calculating target OCS, target irradiance, sky background luminance, target magnitude, signal-to-noise ratio (SNR), and detection probability. By integrating solar radiation properties, observer-site positioning, and celestial-terrestrial background sphere radiation characteristics, a graphics processing unit (GPU) accelerated framework combined with shading languages is implemented to compute time-dependent optical scattering properties, including target OCS, detector-received target/background optical power, target magnitude, SNR, detection probability, and synthetic brightness imagery. Experimental validation using spherical and cylindrical objects confirms the accuracy of the OCS calculations. Simulations under varying observer locations, reflective properties, and detection windows demonstrate the rationality of the computed optical scattering characteristics. This study provides a complete set of formulas, parameters, and results, offering significant value for research on space target optical scattering modeling and image-based recognition.
Optical scattering characteristics are crucial features of space targets and play a vital role in target recognition and detection systems. Traditional methods are limited in simulating optical scattering properties -which only provide optical cross-section (OCS), scattering characteristics, or synthetic target images. To address the above limitations and meet requirements of rendering spatial target, this paper conducts a comprehensive study on the computational modeling of optical scattering characteristics for space targets. A systematic workflow is proposed, along with formulas for calculating target OCS, target irradiance, sky background luminance, target magnitude, signal-to-noise ratio (SNR), and detection probability. By integrating solar radiation properties, observer-site positioning, and celestial-terrestrial background sphere radiation characteristics, a graphics processing unit (GPU) accelerated framework combined with shading languages is implemented to compute time-dependent optical scattering properties, including target OCS, detector-received target/background optical power, target magnitude, SNR, detection probability, and synthetic brightness imagery. Experimental validation using spherical and cylindrical objects confirms the accuracy of the OCS calculations. Simulations under varying observer locations, reflective properties, and detection windows demonstrate the rationality of the computed optical scattering characteristics. This study provides a complete set of formulas, parameters, and results, offering significant value for research on space target optical scattering modeling and image-based recognition.
, Available online , doi: 10.11884/HPLPB202537.250118
Abstract:
Aiming at the phenomenon that unmanned aerial vehicle (UAV) data links in the battlefield environment are easily affected by electromagnetic interference (EMI) and lead to frame synchronization failure, this paper takes the Direct Sequence Spread Spectrum (DSSS) type data link as the research object. Through mechanistic analysis of interference, and specifically addressing the front-door coupling effect of such interference, loss-of-lock threshold models for two typical interference scenarios, in-band single-source single-tone and dual-source dual-tone interferences, are proposed. To validate the effectiveness of the model, taking a certain type of UAV data link as the test object, EMI injection tests are conducted for both single-source and dual-source interference scenarios. The loss-of-lock thresholds of different interferences are obtained. The results demonstrate that the theoretical values of the loss-of-lock threshold align with the experimental trends, thereby verifying the model's validity. These models can provide a theoretical b1asis for experimental design. Finally, the impact patterns of single-source and dual-source interference on the data link are investigated. The study reveals: the trends of the single-source interference loss-of-lock thresholds with the working signal power and interference frequency, and the powers of interference 1 at loss-of-lock status in dual-source interferences with the working signal power, interference 1 frequency, and interference 2 power and frequency.
Aiming at the phenomenon that unmanned aerial vehicle (UAV) data links in the battlefield environment are easily affected by electromagnetic interference (EMI) and lead to frame synchronization failure, this paper takes the Direct Sequence Spread Spectrum (DSSS) type data link as the research object. Through mechanistic analysis of interference, and specifically addressing the front-door coupling effect of such interference, loss-of-lock threshold models for two typical interference scenarios, in-band single-source single-tone and dual-source dual-tone interferences, are proposed. To validate the effectiveness of the model, taking a certain type of UAV data link as the test object, EMI injection tests are conducted for both single-source and dual-source interference scenarios. The loss-of-lock thresholds of different interferences are obtained. The results demonstrate that the theoretical values of the loss-of-lock threshold align with the experimental trends, thereby verifying the model's validity. These models can provide a theoretical b1asis for experimental design. Finally, the impact patterns of single-source and dual-source interference on the data link are investigated. The study reveals: the trends of the single-source interference loss-of-lock thresholds with the working signal power and interference frequency, and the powers of interference 1 at loss-of-lock status in dual-source interferences with the working signal power, interference 1 frequency, and interference 2 power and frequency.
, Available online , doi: 10.11884/HPLPB202537.250120
Abstract:
Background Purpose Methods Results Conclusions
Unmanned aerial vehicles (UAVs), representing advanced combat capabilities in new domains, have become essential weaponry in modern warfare. The proliferation of frequency-dependent equipment and rapid advancements in counter-UAV technologies have resulted in increasingly complex electromagnetic environments. High-power microwave (HPM) radiation, characterized by high power, tunable carrier frequency, and complex coupling effects, can effectively jam or damage UAV systems. The datalink, acting as the UAV’s ‘brain,’ is particularly vulnerable to HPM interference. Consequently, research into HPM coupling mechanisms and protection methods for UAV datalink is vital for enhancing UAV resilience.
This study investigates the coupling laws and protection methods of HPM radiation on the RF front-end of UAV datalink.
Models of the datalink antenna and RF front-end circuit PCB were developed using Computer Simulation Technology (CST) software. The antenna was irradiated with HPM pulses varying in carrier frequency, pulse width, polarization direction, and rise time. The coupled voltage waveforms at the antenna output ports were analyzed. These voltages were injected into the receiver circuit model to determine the coupled voltage at the pins of the RF chip (Si24R1), simulating the complete HPM field-to-circuit coupling process. A 2.45 GHz PIN limiter was implemented for electromagnetic protection.
(1) The amplitude of the coupled voltage at the Si24R1 RF chip pins exhibited spiking behavior at high carrier frequencies. (2) Coupled voltage decreased significantly with increasing polarization angle. (3) Variations in pulse width and rise time had minimal effect on coupled voltage amplitude. (4) The PIN limiter significantly reduced the coupled voltages while maintaining signal reception quality, enhancing the datalink’s electromagnetic protection.
This work quantifies HPM coupling laws on RF front-end circuit under varying parameters. Implementing PIN limiter on the RF front-end significantly attenuates electromagnetic interference, providing a validated reference for UAV electromagnetic protection.
, Available online , doi: 10.11884/HPLPB202537.250069
Abstract:
A trapezoidal double ridge waveguide slow wave structure has been proposed to further enhance the interaction impedance and output power of backward wave oscillators. Compared to conventional sine double ridge waveguide and flat-roofed sine double ridge waveguide, significant improvements in both the axial interaction impedance at the center of the electron beam channel and the average interaction impedance across the cross-section are observed, while maintaining a similar normalized phase velocity. Simulation results indicate that within the frequency range of 320～360 GHz, the average interaction impedance of the trapezoidal double ridge waveguide is increased by 78.33% to 86.97% compared to the sine double ridge waveguide, and by at least 46.65% compared to the flat-roofed sine double ridge waveguide. Under the same operating conditions and frequency range, the output power of the trapezoidal double ridge waveguide backward wave oscillator in the 340 GHz band is measured to be 5.55～8.03 W, representing an increase of 26.97% to 73.44% compared to the sine double ridge waveguide and an enhancement of 33.65% to 52.47% over the flat-roofed sine double ridge waveguide. At this point, all three types of backward wave oscillators are optimized for tube length, with the trapezoidal double ridge waveguide backward wave oscillator being at least 16.5% shorter than the other two structures.
A trapezoidal double ridge waveguide slow wave structure has been proposed to further enhance the interaction impedance and output power of backward wave oscillators. Compared to conventional sine double ridge waveguide and flat-roofed sine double ridge waveguide, significant improvements in both the axial interaction impedance at the center of the electron beam channel and the average interaction impedance across the cross-section are observed, while maintaining a similar normalized phase velocity. Simulation results indicate that within the frequency range of 320～360 GHz, the average interaction impedance of the trapezoidal double ridge waveguide is increased by 78.33% to 86.97% compared to the sine double ridge waveguide, and by at least 46.65% compared to the flat-roofed sine double ridge waveguide. Under the same operating conditions and frequency range, the output power of the trapezoidal double ridge waveguide backward wave oscillator in the 340 GHz band is measured to be 5.55～8.03 W, representing an increase of 26.97% to 73.44% compared to the sine double ridge waveguide and an enhancement of 33.65% to 52.47% over the flat-roofed sine double ridge waveguide. At this point, all three types of backward wave oscillators are optimized for tube length, with the trapezoidal double ridge waveguide backward wave oscillator being at least 16.5% shorter than the other two structures.
, Available online , doi: 10.11884/HPLPB202537.250152
Abstract:
Background Purpose Methods Results Conclusions
High Power Microwave can destroy key components of communication system through front door coupling, resulting in system performance degradation or failure. For receivers with a single RF channel, the degree of system performance degradation can generally be evaluated using the effect results at the device level.
However, for phased array communication systems, the assessment of the system-level damage effect of HPM is a challenge. This is because there are numerous RF channels in the system, and the damage of each channel is not consistent, making it difficult to apply the effect results at the device level to evaluate the system performance.
To verify the asymmetric damage effect of HPM on phased array communication systems and assess the impact of this asymmetric damage on system performance, based on theoretical analysis, this paper established a semi-physical simulation experiment and system-level irradiation experiment method, and conducted research on the asymmetric damage effect of typical phased array communication systems. The study investigated the additional impact of amplitude and phase inconsistency on system performance and carried out system-level verification experiments.
The results show that when the phased array communication system was damaged by HPM, asymmetric damage occurs between channels, affecting the synthesis of the phased array antenna beam, and further deteriorating the system performance.
Moreover, the greater the amplitude and phase inconsistency, especially the greater the phase inconsistency, the greater the additional loss of system performance.
, Available online , doi: 10.11884/HPLPB202537.250048
Abstract:
In order to achieve broadband high-power synthesis output in the microwave wave band, this paper designs and develops a novel high-power, broadband four-way rectangular waveguide TE10 mode to circular waveguide TE01 mode conversion power synthesizer. This mode conversion power synthesizer consists of two parts, namely the structure of four rectangular waveguide TE10 mode synthesis and transformation to cross waveguide TE22 mode, and the structure of cross waveguide TE22 mode transformation to over mode circular waveguide TE01 mode. The simulation results show that in the Ku-band of 15.2−18.2 GHz, the synthesis conversion efficiency of TE10-TE01 mode is greater than 99.4%, and it can withstand a maximum pulse power output of 1.6 MW. The back-to-back cold test experiment of the experimental verification sample shows that the lowest synthesis efficiency of the power synthesizer in the frequency range of 15.2−18.2 GHz is 94%. The simulation results and cold test experiments show that the mode conversion power synthesizer has the characteristics of large working bandwidth, high synthesis efficiency, and large power capacity, which can effectively solve the problem of high-power synthesis output in microwave band and millimeter wave low-end band.
In order to achieve broadband high-power synthesis output in the microwave wave band, this paper designs and develops a novel high-power, broadband four-way rectangular waveguide TE10 mode to circular waveguide TE01 mode conversion power synthesizer. This mode conversion power synthesizer consists of two parts, namely the structure of four rectangular waveguide TE10 mode synthesis and transformation to cross waveguide TE22 mode, and the structure of cross waveguide TE22 mode transformation to over mode circular waveguide TE01 mode. The simulation results show that in the Ku-band of 15.2−18.2 GHz, the synthesis conversion efficiency of TE10-TE01 mode is greater than 99.4%, and it can withstand a maximum pulse power output of 1.6 MW. The back-to-back cold test experiment of the experimental verification sample shows that the lowest synthesis efficiency of the power synthesizer in the frequency range of 15.2−18.2 GHz is 94%. The simulation results and cold test experiments show that the mode conversion power synthesizer has the characteristics of large working bandwidth, high synthesis efficiency, and large power capacity, which can effectively solve the problem of high-power synthesis output in microwave band and millimeter wave low-end band.
, Available online , doi: 10.11884/HPLPB202537.250107
Abstract:
Background Purpose Methods Results Conclusions
The operational reliability of Unmanned Aerial Vehicles (UAVs) is critically dependent on their Global Navigation Satellite Systems (GNSS). However, in increasingly contested electromagnetic environments, the inherent weakness of GNSS signals makes them highly susceptible to suppression jamming, leading to performance degradation or mission failure. Existing test standards often focus on single-jammer, static scenarios and lack the quantitative rigor needed to assess the performance of advanced multi-element antenna systems under complex, dynamic conditions.
This research aims to address this gap by developing and validating a standardized, quantitative test methodology for evaluating the anti-suppression-jamming performance of UAV GNSS systems. The objective is to create a reproducible framework that can simulate dynamic, multi-source interference and provide a comprehensive assessment from the RF front-end to the complete system level.
A hybrid test methodology integrating direct Radio Frequency (RF) injection and over-the-air (OTA) spatial irradiation was established within a microwave anechoic chamber. This “injection-irradiation” approach facilitates a full-link evaluation. Both static and dynamic tests were conducted on a seven-element GNSS adaptive array receiver. Static tests involved assessing performance against an increasing number of jammers (one to six) from fixed spatial locations. Dynamic tests simulated UAV maneuvers by placing the receiver on a turntable rotating at 2°/s, exposing it to a changing interference geometry. Performance was quantified by the jamming-to-signal (J/S) ratio threshold, carrier-to-noise ratio, and positioning success rate.
Static tests quantified a distinct saturation effect on the receiver’s spatial filtering capability; the J/S ratio threshold for positioning failure decreased from 106 dB against a single continuous-wave jammer to 60 dB against six broadband noise jammers. Critically, dynamic tests revealed a complex spatio-temporal coupling effect. In the six-jammer scenario, the system maintained a 100% positioning success rate at a J/S ratio of 70 dB while rotating, paradoxically outperforming its 60 dB static failure threshold. This demonstrates that the constant change in interference geometry can prevent the algorithm from settling into a worst-case nulling solution.
The proposed combined injection-irradiation and dynamic test methodology provides a robust and standardized framework for the quantitative assessment of UAV GNSS anti-jamming capabilities. The findings reveal that static tests alone are insufficient for predicting performance, as dynamic conditions can fundamentally alter the system’s response to multi-source interference. This research offers a critical tool for the realistic evaluation, design optimization, and validation of navigation systems intended for operation in complex electromagnetic environments.
, Available online , doi: 10.11884/HPLPB202537.250085
Abstract:
Background Purpose Methods Results Conclusions
Transient intense electromagnetic pulses, characterized by extremely high peak field strength and broad frequency domain distribution, pose severe electromagnetic safety threats to electronic systems. Their accurate measurement is crucial for evaluating radiation source performance and the effectiveness of protection measures. However, ground-reflected waves often cause significant waveform distortion in far-field measurements. Existing narrow-spectrum suppression methods fail due to bandwidth limitations, environmental adjustment approaches are impractical in complex scenarios, and traditional array beamforming techniques are restricted by signal correlation requirements.
To address the waveform distortion caused by ground-reflected waves in far-field measurements of transient intense electromagnetic pulses, this study designs a monopole array-based waveform recovery algorithm. It aims to eliminate ground scattering interference and accurately extract direct waves, providing support for related measurements and evaluations.
The principle of direct wave extraction based on the monopole array was derived in both frequency and time domains. Potential error sources and corresponding optimization schemes were analyzed. A measurement system was built under ground reflection conditions for experimental tests, and the performance of different algorithms was compared.
Experimental results show that the direct waves extracted by the proposed algorithm match the reference direct waves well, with amplitude error within 0.2dB and main waveform fidelity coefficient greater than 0.99. The time-domain algorithm is more concise and less affected by interference, while the frequency-domain algorithm enables direct wave recovery with a single system, making it more cost-effective. Compared with traditional technologies, the algorithm expands the applicable frequency band and significantly reduces amplitude calculation error.
The proposed waveform recovery algorithm can effectively suppress ground scattering effects and accurately extract direct waves. It provides reliable support for parameter separation in transient pulse measurements and state evaluation of radiation systems.
, Available online , doi: 10.11884/HPLPB202537.250143
Abstract:
Background Purpose Methods Results Conclusions
Precision-guided ammunition for electromagnetic railguns is gradually becoming a key area of competition among nations, which imposes new requirements on fuzes suitable for electromagnetic railgun ammunition. Modern fuzes contain a large number of electronic components, and during the launch of electromagnetic railgun projectiles, the fuze is exposed to strong magnetic fields. These fields can interfere with the fuze's electronic components, leading to malfunction or even damage. As a result, most mature electromagnetic railguns currently use kinetic energy projectiles or mechanical fuzes.
A reasonable arrangement of the fuze circuit module can reduce the structural thickness and weight of the electromagnetic shielding shell for the fuze circuit, while effectively ensuring the working performance of the fuze circuit.
In this paper, a quasi-steady-state simulation model of the electromagnetic railgun is established. The electromagnetic induction performance of the circuit module under two different arrangement modes is calculated and analyzed. The responses such as the magnetic field distribution, induced current, current volume force density, and induced electromotive force on the fuze circuit module are obtained respectively.
When the fuze circuit module is arranged parallel to the projectile axis, although the overall magnetic field strength is greater than when arranged perpendicular to the projectile axis, the peak magnetic field strength in the perpendicular arrangement covers an entire surface of the circuit board, whereas in the parallel arrangement, the peak magnetic field strength is only at the edge of the circuit module's end. When the fuze circuit module is arranged parallel to the projectile axis, the induced eddy current, electromagnetic volume force density, and induced electromotive force are all significantly smaller than those in the perpendicular arrangement.
For the fuze circuit module of electromagnetic railgun ammunition, arranging it parallel to the projectile axis can more effectively reduce the impact of the electromagnetic field during launch. Additionally, sensitive components should be avoided from being placed at the ends and edges of the circuit module. This can greatly reduce the structural size, thickness and weight of the shell for electromagnetic shielding of the fuze circuit components, so as to optimize the overall structure of the fuze and reduce the total weight of the fuze.
, Available online , doi: 10.11884/HPLPB202537.250108
Abstract:
Aluminum materials are widely applied in aviation, aerospace, military and other fields. When strong explosions generate X-rays and irradiate aluminum materials, it will cause irradiation damage, phase transformation, ablation and other effects on the materials. This paper conducts simulation of the thermal effect during the interaction between X-rays and materials through multi-scale modeling, taking into account the temperature changes of both the electronic system and the lattice system. The TTM-MD model is selected to carry out the simulation of the thermal effect during the interaction between X-rays and aluminum foil. The energy deposition of X-ray irradiation on aluminum foil and the heat conduction process within the material is deeply studied. By analyzing the specific influence of X-ray energy on the thermal effect of aluminum foil, the evolution laws of physical parameters such as electron and lattice temperatures, material density, etc. with time are obtained. During the X-ray irradiation of aluminum foil, the energy of X-rays is absorbed by the aluminum foil material and converted into thermal energy. This heating effect will cause the surface density of the aluminum foil to decrease and gradually deposit deeper; meanwhile, the temperature increase caused by irradiation also leads to the dynamic response of the internal pressure of the aluminum foil, which first increases sharply and then gradually stabilizes. This paper explores the mechanism of the influence of X-ray irradiation on the thermal effect of aluminum foil, providing a comprehensive perspective for understanding the thermal effect of aluminum foil under X-ray irradiation.
Aluminum materials are widely applied in aviation, aerospace, military and other fields. When strong explosions generate X-rays and irradiate aluminum materials, it will cause irradiation damage, phase transformation, ablation and other effects on the materials. This paper conducts simulation of the thermal effect during the interaction between X-rays and materials through multi-scale modeling, taking into account the temperature changes of both the electronic system and the lattice system. The TTM-MD model is selected to carry out the simulation of the thermal effect during the interaction between X-rays and aluminum foil. The energy deposition of X-ray irradiation on aluminum foil and the heat conduction process within the material is deeply studied. By analyzing the specific influence of X-ray energy on the thermal effect of aluminum foil, the evolution laws of physical parameters such as electron and lattice temperatures, material density, etc. with time are obtained. During the X-ray irradiation of aluminum foil, the energy of X-rays is absorbed by the aluminum foil material and converted into thermal energy. This heating effect will cause the surface density of the aluminum foil to decrease and gradually deposit deeper; meanwhile, the temperature increase caused by irradiation also leads to the dynamic response of the internal pressure of the aluminum foil, which first increases sharply and then gradually stabilizes. This paper explores the mechanism of the influence of X-ray irradiation on the thermal effect of aluminum foil, providing a comprehensive perspective for understanding the thermal effect of aluminum foil under X-ray irradiation.
, Available online , doi: 10.11884/HPLPB202537.250033
Abstract:
Laser-driven high-brightness betatron radiation has great potentials for its broad applications in the detection of ultrafast processes (such as shock waves or implosion processes) in high energy density physics. Here a tube-like gas-cell target is proposed to generate a near-critical-density (NCD) plasma, which has a sharped rising edge with a length scale of hundreds of μm. Such a gas-cell target has the advantages of low back pressure and small jet volume. Moreover, due to the confinement of the gas chamber walls, it can more stably generate a plateau-shaped gas density distribution. Particle-in-cell (PIC) simulations of the the petawatt femtosecond laser interacting with such a NCD plasma were carried out to study the electron acceleration as well as the betatron radiation. It was shown that, with the appropriate gas density and pulse duration, a steady plasma channel can be well formed. In the channel, the electrons firstly undergo the wakefield acceleration. Then these energetic electrons directly interact with the laser tail, where the efficient betatron resonance and the direct laser acceleration happen, thus resulting in the great enhancement of both the yield and cut-off energy. The transverse oscillation of energetic electrons in the plasma channel leads to the production of high brightness betatron radiation, which has a critical photon energy of 8keV and a brightness of\begin{document}$ 1.75\times {10}^{20}\;\mathrm{p}\mathrm{h}\cdot {\mathrm{s}}^{-1}\cdot {\mathrm{mm}}^{-2}\cdot {\mathrm{m}\mathrm{rad}}^{-2}\cdot {\left(0.1\mathrm{{\text{%}}}\mathrm{b}\mathrm{w}\right)}^{-1} $\end{document} ![]()
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Laser-driven high-brightness betatron radiation has great potentials for its broad applications in the detection of ultrafast processes (such as shock waves or implosion processes) in high energy density physics. Here a tube-like gas-cell target is proposed to generate a near-critical-density (NCD) plasma, which has a sharped rising edge with a length scale of hundreds of μm. Such a gas-cell target has the advantages of low back pressure and small jet volume. Moreover, due to the confinement of the gas chamber walls, it can more stably generate a plateau-shaped gas density distribution. Particle-in-cell (PIC) simulations of the the petawatt femtosecond laser interacting with such a NCD plasma were carried out to study the electron acceleration as well as the betatron radiation. It was shown that, with the appropriate gas density and pulse duration, a steady plasma channel can be well formed. In the channel, the electrons firstly undergo the wakefield acceleration. Then these energetic electrons directly interact with the laser tail, where the efficient betatron resonance and the direct laser acceleration happen, thus resulting in the great enhancement of both the yield and cut-off energy. The transverse oscillation of energetic electrons in the plasma channel leads to the production of high brightness betatron radiation, which has a critical photon energy of 8keV and a brightness of
