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, Available online , doi: 10.11884/HPLPB202638.250398
Abstract:
Background Purpose Methods Results Conclusions
SiC-based light-initiated multi-gate semiconductor switches (LIMS) deliver superior response speeds due to the faster injection of photo-generated carriers compared to conventional electrically injected carriers. They can be used in a variety of applications, including radars, accelerators, and pulse sources.
Regarding the problems such as the long falling edge and slow turn-off speed of LIMS, an anode structure design with turn-off capability is proposed.
The model and its parameters are calibrated based on experimental data, and the simulation is used to study the conduction characteristics of devices with a turn-off anode structure.
The simulation results show that devices with a turn-off anode structure can achieve positive feedback in the pnpn configuration following laser activation, thereby increasing the conduction current. When the laser pulse ends, the recombination of photo-generated carriers and the extraction of carriers from the base region by the turn-off anode structure significantly enhance the turn-off speed of the device.
With a 4 kV anode bias and a peak current of several hundred amperes, the modified LIMS reduces the full-width-at-half-maximum of the current pulse from 0.79 µs to <100 ns and shortens the turn-off time to 0.6 µs. These results indicate suitability for repetitive operation at kilohertz frequencies and above.
, Available online , doi: 10.11884/HPLPB202638.250367
Abstract:
Background Purpose Methods Results Conclusions
High-energy flash X-ray photography has important applications in the hydrodynamic experiments. As an important means of generating multi-pulse X-ray, the technical scheme of multi-pulse linear induction accelerators (LIA) of each countries have their own characteristics.
Based on requirements for the compactness, mobility, and high reliability of multi-pulse LIAs, the project team is exploring various novel multi-pulse power source technologies that can be used for multi-pulse LIAs.
In this paper, a 100 kV four-pulse generation technology is explored, that is, a low-pressure pseudo-spark switch of tens of kV is used to drive the Blumlein line of tri-coaxial cables to generate multi-pulse high voltage, and the multi-pulse high voltage of tens of kV is superimposed by an induction voltage adder to generate a multi-pulse high voltage of 100 kV. The same four sets of pulse high voltage generators are used to output multi-pulse high voltage of 100 kV, which are converged by a coaxial high-voltage diode to obtain four-pulse high voltage output of 100 kV.
Simulation and experimental results show that the scheme could generate four-pulse high voltage of more than 100 kV with adjustable pulse interval.
This compact and movable 100 kV four-pulse high voltage generator is expected to become a new multi-pulse power source for multi-pulse LIAs.
, Available online , doi: 10.11884/HPLPB202638.250399
Abstract:
Background Purpose Methods Results Conclusions
High-power pulsed applications increasingly require power supplies capable of large-current bipolar output and flexible controllability. However, achieving high power density while maintaining pulse precision and current-sharing stability remains a significant challenge in pulse source design.
This work aims to design and implement a compact, integrated bipolar pulsed current supply system that utilizes a paralleled Silicon Carbide (SiC) MOSFET full-bridge architecture to meet the demands of medium-voltage, high-power pulsed applications.
The proposed system integrates the main power stage, isolated drivers, auxiliary power supplies, and protection module on a single printed circuit board (PCB), featuring both high power density and scalability.
Experimental results demonstrate that, under DC bus voltages from 50 V to 300 V, the peak output current exhibits excellent linear correlation with the bus voltage, while pulse-width adjustment enables continuously controllable peak current with a maximum enhancement of 37%. The system is capable of delivering bipolar pulse currents up to ±300 A, confirming the compatibility of high-current output with compact integration. In addition, at a 500\begin{document}$ \;ns $\end{document}
These findings indicate that the proposed compact integrated design successfully balances large-current bipolar pulsed output and parameter adjustability, providing experimental evidence and design guidance for the miniaturization and engineering implementation of medium-voltage and high-power pulse sources.
, Available online , doi: 10.11884/HPLPB202638.250264
Abstract:
Background Purpose Methods Results Conclusions
The quasi-square wave output characteristic of PFN-Marx generator is a pair of contradictions with the compactness of the setup. With the higher requirement of the compactness of the setup, the inter stage electromagnetic coupling of PFN wave transmission becomes more and more obvious, which has a significant effect on the pulse modulation characteristics of PFN and further affects the quasi-square wave output characteristics of the generator.
It is necessary to conduct an investigation into the electromagnetic coupling during the wave transmission process of the PFN-Marx generator and derive the corresponding calculation formulas. This allows for the avoidance of specific electromagnetic couplings during the design phase, ensuring both the quality of the output waveform and the compactness of the device.
This paper conducts electromagnetic coupling analysis of PFN during the discharging process of PFN Marx generator. Firstly, the electromagnetic coupling phenomenon in the PFN and between the PFNs are analyzed by theoretical derivation, and the calculation formulas are obtained. Then, the 3D model of the typical PFN Marx generator is built up for field circuit simulation. Finally, a single-stage generator and a multi-stage generator are built for experimental verification.
The experimental results verify the theoretical analysis and simulation results, showing good consistency. The preliminary design optimization directions for the PFN-Marx generator can be outlined as follows:1. Maintain appropriate inter-wire spacing;2. Increase design redundancy to compensate for electromagnetic coupling;3. Keep the transmission lines neat and regular to minimize unnecessary electromagnetic coupling.
Based on the above results, we can improve the understanding of electromagnetic coupling in the wave transmission of PFN-Marx generator, so as to avoid partial electromagnetic coupling in design and improve the square wave output ability of PFN-Marx generator. This paper can provide technical reference for the development of quasi-square wave technology and compact technology of PFN-Marx generator.
, Available online , doi: 10.11884/HPLPB202638.250342
Abstract:
Background Purpose Methods Results Conclusions
In all-solid-state Marx pulse generators, the isolated gate driver plays a critical role in ensuring reliable high-voltage and high-speed switching. Conventional isolation driving schemes based on magnetic-core transformers often suffer from large volume, high cost, and poor integration, which limit further miniaturization and system-level integration.
To address these issues, this study proposes a synchronous isolated gate driving scheme based on a PCB-embedded coreless transformer, aiming to reduce driver size and cost while improving integration and manufacturability for all-solid-state Marx pulse generator applications.
The proposed coreless transformer was first modeled, and its key electromagnetic parameters were extracted using Q3D electromagnetic simulation and validated through experimental measurements. Based on theoretical analysis and LTspice simulations of the driving circuit, the operating principles and driving sequence characteristics were investigated and compared with those of conventional magnetic-core transformer-based drivers. Finally, a prototype driving system was developed and experimentally evaluated.
Simulation and experimental results show that the proposed PCB coreless transformer-based driving scheme exhibits a wide dynamic driving range, excellent electrical isolation performance, and good compatibility with standard PCB manufacturing processes. The experimental waveforms are consistent with theoretical analysis and simulation results, confirming the correctness of the proposed design and modeling approach.
The proposed synchronous isolated driving scheme based on a PCB coreless transformer provides an effective solution to the challenges of volume, cost, and integration in conventional isolation drivers for all-solid-state Marx pulse generators. The results demonstrate its feasibility and strong potential for practical engineering applications in compact and highly integrated pulsed power systems.
, Available online , doi: 10.11884/HPLPB202638.250453
Abstract:
Background Purpose Methods Results Conclusions
Solid-state linear transformer drivers (SSLTDs), featuring modular architecture, solid-state implementation, high reliability, and high repetition-rate capability, have become an important development direction in pulsed-power technology.
This paper proposes and develops a compact SSLTD based on a stacked Blumlein pulse generation module (SBPGM) and experimentally validates its performance.
The SBPGM integrates a hybrid pulse-forming network composed of high-voltage ceramic capacitors and the distributed inductance of PCB traces, a series--parallel IGBT switching array, and inductively isolated gate-driver circuits. The proposed common-ground bipolar-charging SBPGM topology eliminates the need for high-voltage isolation within an individual module and equalizes the driver insulation voltage stress, thereby significantly improving the compactness and reliability of the overall system.
Circuit simulations of a single SBPGM verify the voltage-doubling behavior and the desired high-voltage isolation characteristics, producing a 10.8 kV output under a charging voltage of 5.5 kV. Based on this module, a 30-stage SSLTD prototype is constructed. With a per-stage charging voltage of 5 kV and a 90 Ωwater load, the prototype generates a 279 kV quasi-square pulse with a peak current of 3.1 kA, a pulse width of 77 ns, and a rise time of 22.4 ns at a repetition rate of 50 Hz, corresponding to a peak power of 0.9 GW.
This SSLTD adopts a modular, scalable architecture. The SBPGMs are electrically and mechanically consistent yet independent, enabling straightforward voltage scaling and simplified implementation. Experiments confirm compact size and high power density, demonstrating the potential of high-repetition-rate all-solid-state pulsed-power sources.
, Available online , doi: 10.11884/HPLPB202638.250395
Abstract:
Background Purpose Methods Results Conclusions
Alumina (Al2O3) ceramics are extensively employed as insulating components in vacuum electronic devices. However, under high voltage, charge accumulation on their surface can easily lead to surface flashover, which severely degrades the insulation performance of the device and affects its operation. Therefore, enhancing the vacuum surface insulation performance of Al2O3 ceramics holds significant academic value and practical implications. Surface coating represents a widely adopted strategy for enhancing the insulation performance of Al2O3 ceramics. Nevertheless, the specific influence of the glass phase within the coating on the insulating properties remains largely unexplored.
The present work is dedicated to exploring how the glass phase in coatings affects the vacuum insulation performance of Al2O3 ceramics.
A Cr2O3-based coating was fabricated on the surface of Al2O3 ceramics, and the effects of the glass phase within the coating on phase structure, surface morphology, secondary electron emission coefficient (SEE), surface resistivity, and the vacuum insulation performance of the coated ceramics were systematically investigated.
The results indicate that Al element from the substrate diffuses into the coating under high-temperature firing. The content of Cr2O3 phase in the coating exhibits a gradual decrease and eventually disappears with the rise of the glass phase content, causing it to fully react with the ceramic substrate to form Al2-xCrxO3 (0＜x＜2)、Mg(Al2-yCry)O4 (0＜y＜2), along with small amounts of ZnAl2O4 and (Na,Ca)Al(Si,Al)3O8. The coating improves the surface grain homogeneity and the density of the ceramic surface, although variations in the glass phase content have a negligible effect on its microstructure. Additionally, the Cr2O3 coating reduces both the SEE coefficient and the surface resistivity of the Al2O3 ceramic. However, as the glass phase content in the coating increases, both the SEE coefficient and surface resistivity of the coated ceramics exhibit a gradual upward trend. The optimal insulation performance is achieved when the glass phase content reaches 20%. At this point, the vacuum surface hold-off strength attains 119.63 kV/cm.
Modulation of the glass phase content in the surface coating enables the tunability of the vacuum surface insulation performance of the Al2O3 ceramics, with the performance improvement stemming from the decreased SEE coefficient and the appropriate surface resistivity.
, Available online , doi: 10.11884/HPLPB202638.250444
Abstract:
Background Purpose Methods Results Conclusions
The rapid advancement of high-power pulse technology towards practical application imposes higher demands on the self-breakdown stability of high-voltage gas switches.
This paper proposes a pre-ionization cathode switch concept, which utilizes an auxiliary annular blade edge to regulate initial electrons and an annular hemisphere to conduct the main current. A 300 kV-level pre-ionization annular cathode gas switch was designed.
With a switch gap of 35 mm, the field enhancement factor at the blade edge of the pre-ionization switch was designed to be 6.2, resulting in a ratio of 3.2 compared to the field enhancement factor at the hemisphere. Experimental investigations on the breakdown characteristics under microsecond-level pulses were conducted.
The results indicate that in nitrogen at 0.5 MPa and a repetition rate of 1 Hz, the pre-ionization gas switch achieved an average breakdown voltage of 322.5 kV with a amplitude jitter of 0.44%. Compared to a pure annular hemispherical switch, the pre-ionization switch exhibits a 17.6% reduction in breakdown voltage and an 82% decrease in amplitude jitter.
The experimental study demonstrates that this pre-ionization gas switch offers significant advantages in achieving high voltage and low jitter.
, Available online , doi: 10.11884/HPLPB202638.250079
Abstract:
Background Purpose Methods Results Conclusions
In recent years, magnetized laser-plasma research has gained significant importance in multiple frontier fields such as magneto-inertial confinement fusion, magnetic reconnection, collisionless shocks, and magnetohydrodynamic instabilities. Pulsed magnetic field devices have become the mainstream experimental approach, as they can generate magnetic field parameters that meet experimental requirements in terms of strength, spatial scale, and duration. Such devices have been integrated into multiple large-scale laser facilities worldwide, and our research group has also successfully developed several pulsed magnetic field systems adaptable to laser setups of different scales. However, existing devices still face two major challenges: first, strong electromagnetic interference affects data acquisition and equipment safety; second, advances in physical experiments demand higher magnetic field strengths.
This study presents a novel coaxial-structure pulsed magnetic field device, designed to optimize the circuit configuration for suppressing electromagnetic interference (EMI) and enhancing magnetic field strength, thereby providing a more reliable high-field environment for magnetized laser-plasma experiments.
The experiment employs an all-coaxial architecture to enhance electromagnetic compatibility. Multiple soft coaxial cables are connected in parallel to link a 5 μF high-voltage coaxial capacitor with a rigid coaxial transmission line inside the vacuum target chamber, thereby minimizing system inductance.
At 40 kV charging voltage, a discharge current with 105 kA peak intensity, a rise time of 1.2 μs, and a flat top width of 1.4 μs is produced, which generates a intense magnetic field of 22 T in the center of a three-turn magnetic field coil with 12 mm diameter. Compared with our previous pulsed intense magnetic field device, the present device can generate larger current and stronger magnetic field, while the free-space EM noise and potential jitter (voltage fluctuation) of the vacuum chamber are significantly reduced.
Experimental results demonstrate that the key performance of this device has reached the mainstream advanced level of international counterparts, such as relevant systems from the U.S. LLNL, France's LULI, and Germany’s HZDR. This device combines high magnetic field strength, microsecond-level flat-top stability, and low electromagnetic interference, providing precisely controllable strong magnetic field experimental conditions—previously difficult to achieve—for frontier research areas such as magneto-inertial confinement fusion, laboratory astrophysics, magnetohydrodynamic instabilities, and pulsed laser deposition coating.
, Available online , doi: 10.11884/HPLPB202638.250337
Abstract:
Background Purpose Methods Results Conclusions
As an important branch of electromagnetic launch, multi-stage synchronous induction coil gun has become one of the hotspots of launch research because of its non-contact, linear propulsion and high efficiency. Among them, the armature outlet velocity is an important index, which is affected by many factors such as the structural parameters, material parameters and coil circuit parameters. However, the existing research lacks theoretical analysis on various factors.
The purpose of this paper is to analyze theoretical approaches for improving the armature outlet velocity, and to explore the factors affecting it.
Based on the equivalent circuit model, this paper derives the analytical formula of armature induced eddy current., and investigates these factors affecting the outlet velocity via finite element simulation.
Theoretical analysis shows that reducing the total inductance of the coil-armature equivalent circuit can increase the armature outlet velocity. Simulation results show that under the same initial electric energy, reducing the number of turns of coils, reducing the cross-sectional shape factor of rectangular wire, increasing the thickness and length of armature, and reducing the line inductance can improve the armature outlet velocity. Considering various factors, the simulated outlet velocity of 32 kg armature driven by 5-stage coil can reach 202.1 m/s, and the launch efficiency is 33.3%. The influence of various factors on the armature is in line with the theoretical analysis results.
The research content of this paper provides some theoretical support for the design of multi-stage synchronous induction coil gun scheme.
, Available online , doi: 10.11884/HPLPB202638.250420
Abstract:
Background Purpose Methods Results Conclusions
High-power Yb-doped fiber lasers operating in the 1 μm band have been widely applied in fields such as laser processing, biomedicine, and national defense security. However, with the continuous increase in output power, traditional large-core fibers are susceptible to transverse mode instability (TMI) and stimulated Raman scattering (SRS), among other nonlinear effects. Based on their unique anti-resonant light-guiding mechanism, all-solid anti-resonant silica fibers (AS-ARFs) can realize ultra-large mode area (LMA) propagation while suppressing higher-order modes (HOMs), thus providing an innovative technical approach for balancing high power and high beam quality. Nevertheless, for active Yb-doped AS-ARFs targeting high-power gain applications, the influence mechanism of core refractive index fluctuations on mode characteristics and the fusion-splicing transmission characteristics of “step-index fiber - AS-ARF” structures have not been systematically investigated, which restricts their practical application process.
To address the above problems, this study aims to clarify the critical value of refractive index variation for maintaining the original light-guiding mechanism of AS-ARFs, verify their capabilities of low loss, large mode area and beam quality maintenance, explore the fusion-splicing coupling transmission laws between SIFs and AS-ARFs, quantify the core control parameters of active AS-ARFs, and provide theoretical support for their fabrication process optimization and coupling scheme design.
A six-ring AS-ARF theoretical model was constructed, combined with theoretical derivation and numerical simulation: Comsol Multiphysics was used to analyze the mode characteristics and the influence of refractive index fluctuations, and the Rsoft-BeamPROP module (based on the beam propagation method) was adopted to simulate the light transmission laws in the fusion-splicing coupling scenario.
The critical value of refractive index variation was clarified; the designed AS-ARFs were verified to have the characteristics of low loss, large mode area and excellent beam quality at the target wavelength; the fusion-splicing coupling transmission laws were revealed, and the transmitted energy attenuation was less than 2% when the incident beam diameter matched the core diameter of AS-ARFs.
This study realizes the quantification of core control parameters for active AS-ARFs, laying an important theoretical foundation for the fabrication process optimization of Yb3+-doped AS-ARFs (with a focus on refractive index uniformity control) and the design of practical coupling schemes.
, Available online , doi: 10.11884/HPLPB202638.250439
Abstract:
Background Purpose Methods Results Conclusions
Radar protective enclosures often attenuate electromagnetic waves and reduce the received signal level, especially in high-frequency shallow-layer detection. This attenuation can narrow the usable bandwidth and weaken target responses in practical deployment.
This study aims to design a miniaturized, high-transmittance Frequency Selective Surface (FSS) that restores transmission through an enclosure while keeping a compact unit cell for integration and manufacturing.
We designed a resonant unit that coupled upper and lower metal patches with a metal grid. We used an equivalent-circuit model to describe the structure and to link physical geometry to coupling capacitance and resonance. We then ran full-wave simulations to quantify transmission, bandwidth, and electrical size. We fabricated samples and measured them with microwave test equipment to verify the simulated response under realistic conditions.
The simulations showed stable transmission above 90% across 9.5–10.5 GHz. The design achieved miniaturization, and the unit electrical size was approximately one-thirteenth of the operating wavelength. The measurements confirmed transmission above 90% across 9.6–10.3 GHz. The measured curves matched the simulated trends and resonant features, which supported the circuit-based interpretation.
The proposed miniaturized FSS provides high transmission with a compact footprint and good practical tolerance to deployment constraints. It offers a direct design reference for high-frequency radar enclosures that require both electromagnetic transparency and structural compatibility.
, Available online , doi: 10.11884/HPLPB202638.250301
Abstract:
Background Purpose Methods Results Conclusions
Simultaneous and accurate detection of multiple physical and biochemical parameters, such as refractive index (RI) and temperature, is critically important in complex sensing environments including biological analysis and cancer cell detection. Photonic crystal fiber sensors based on surface plasmon resonance (PCF-SPR) have attracted considerable attention due to their high sensitivity and compact structure. However, achieving ultra-wide RI detection ranges, effective temperature compensation, and low cross-sensitivity within a single fiber platform remains a significant challenge, particularly when higher-order mode excitation and polarization selectivity are required.
The purpose of this study is to propose and numerically investigate a dual-channel PCF-SPR sensor capable of simultaneous RI and temperature sensing over an ultra-wide range, while achieving polarization-resolved mode excitation and reduced cross-interference between sensing channels.
An anchor-shaped asymmetric photonic crystal fiber with orthogonally polished semi-circular surfaces is designed. Gold (Au) and polydimethylsiloxane (PDMS) thin films are selectively deposited on different polished surfaces to construct two independent SPR sensing channels. Polarization-resolved excitation of high-order modes is realized by structural asymmetry and selective coating. A full-vector finite-element method based on COMSOL Multiphysics is employed to analyze mode distributions, loss spectra, and resonance wavelength shifts. Key structural parameters, including air-hole geometry and metal-dielectric layer thicknesses, are systematically optimized to enhance plasmonic coupling strength and mode confinement.
Simulation results indicate that the x-polarized channel coated with Au and PDMS exhibits dual sensitivity to RI and temperature, whereas the y-polarized channel coated only with Au responds exclusively to RI variations of another analyte. The proposed sensor achieves an ultra-wide RI detection range from 1.21 to 1.44, with a maximum RI sensitivity of 14 500 nm/RIU. The temperature sensing range spans from −100 ℃ to 100 ℃, and a peak temperature sensitivity of 4 nm/℃ is obtained. Clear polarization-dependent resonance characteristics and effective channel decoupling are demonstrated.
The proposed dual-channel anchor-shaped PCF-SPR sensor combines ultra-wide RI detection, temperature sensing capability, and polarization-resolved selectivity within a compact fiber structure. Its high sensitivity, flexible channel configuration, and strong resistance to cross-interference make it a promising platform for real-time multi-parameter sensing in complex biological and chemical applications, such as cancer cell detection and biochemical analysis.
, Available online , doi: 10.11884/HPLPB202638.250303
Abstract:
Background Purpose Methods Results Conclusions
Pinhole cameras based on the principle of pinhole imaging are widely used in high-energy-density physics experiments to monitor laser-target interaction regions. However, traditional pinhole cameras often suffer from signal acquisition failures due to the lack of online aiming capability, especially for small targets such as wire targets in facilities like the Xingguang-Ⅲ laser system.
This study aims to develop an X-ray online-aiming pinhole camera for the Xingguang-Ⅲ laser facility, addressing the challenge of precise target alignment under vacuum conditions and enhancing the reliability of signal acquisition.
An integrated design combining a visible-light CCD and an X-ray CCD was implemented. A revolver-type pinhole adjustment device was developed to switch between aiming apertures and imaging pinholes with a concentricity error below 3.5 µm. High-precision two-dimensional pointing adjustments (pitch and tilt) were achieved using a motorized stage, with a targeting accuracy of 15 µm. The visible-light CCD enabled real-time target imaging, while different aperture sizes on a precision adjustment disk facilitated coarse-to-fine aiming.
The camera was tested on the Xingguang-Ⅲ laser facility using a Cu planar target irradiated by a picosecond laser. Clear X-ray spot images were obtained, with a peak intensity of 52,040 and a background noise of approximately 2,500. The full width at half maximum of the spot was 43 µm horizontally and 38 µm vertically, confirming successful online aiming and imaging performance.
The developed X-ray online-aiming pinhole camera fulfills the operational requirements of the Xingguang-Ⅲ laser facility. It enables real-time, high-precision target alignment under vacuum, significantly improving the success rate of signal acquisition in high-energy-density physics experiments.
, Available online , doi: 10.11884/HPLPB202638.250370
Abstract:
Background Purpose Methods Results Conclusions
Laser self-mixing interferometry (SMI) is a highly sensitive and non-contact technique widely used for micro-displacement measurement. However, traditional displacement reconstruction methods typically involve complex phase unwrapping calculations, which increases computational difficulty and limits the efficiency of signal processing in practical applications.
This study aims to propose a novel micro-displacement reconstruction method for semiconductor laser SMI based on convolutional neural networks (CNN). The objective is to achieve direct and accurate reconstruction of micron-scale displacement while bypassing the tedious phase unwrapping process.
The proposed method involves segmenting the SMI signal and using the window-averaged displacement as the label for training the CNN. The architecture of the network consists of three sets of convolutional layers, pooling layers, and Rectified Linear Unit (ReLU) functions. Specifically, the convolutional layers are utilized to extract local displacement features from the SMI signal, the pooling layers are designed to compress feature information and enhance noise immunity, and the ReLU functions help highlight critical displacement features within the signal.
In theoretical simulations, SMI signals with 10 dB noise were input into the trained CNN, resulting in a displacement reconstruction RMSE of 5.3 × 10−8. In experimental tests, SMI signals containing system noise were processed by the network, yielding a reconstructed displacement RMSE of 2.1 × 10−7. The simulation and experimental results demonstrate consistent performance.
Both theoretical and experimental results indicate that the convolutional neural network can effectively achieve micron-level displacement reconstruction by analyzing the temporal segments of SMI signals. This method provides an efficient alternative for semiconductor laser self-mixing interference systems by eliminating the need for complex phase-based algorithms.
, Available online , doi: 10.11884/HPLPB202638.250419
Abstract:
Background Purpose Methods Results Conclusions
Yb(TMHD)3 (ytterbium tris (2,2,6,6-tetramethyl-3,5-heptanedionate)) is the irreplaceable vapor-phase dopant for fabricating high-gain Yb-doped silica laser fibers, and its exact Yb content dictates final fiber performance. The conventional oxalate gravimetric method requires 6 h per sample, incompatible with the real-time feedback demanded by modern preform manufacture.
In order to enhance the production efficiency,
we report a “nitric acid-hydrogen peroxide open-vessel digestion/EDTA complexometric titration” protocol. After 3 min oxidative decomposition of the organic matrix, the solution is buffered with hexamethylenetetramine (pH=5-6) and titrated with standard EDTA using xylenol orange (XO) as indicator.
The stoichiometric Yb3+ : EDTA ratio is 1∶1; the sharp colour change from rose-red to bright yellow with a relative standard deviation (RSD, n=11) of ≤ 0.5%. Mean recoveries for spiked Yb(TMHD)3 ranged 98.2%-100.2%. Results for ten commercial lots deviated <0.3% from the gravimetric reference, while the total analysis time was reduced from 6 h to 15 min.
The procedure is accurate, precise, inexpensive and field-robust, enabling on-site monitoring of Yb loading and immediate optimisation of preform deposition parameters.
, Available online , doi: 10.11884/HPLPB202638.250314
Abstract:
Background Purpose Methods Results Conclusions
High-power fiber lasers have become core devices in key fields such as industrial precision processing, advanced national defense equipment, frontier scientific research, and high-end medical equipment. However, the traditional R&D mode of high-power fiber lasers relies heavily on physical experiments, which are costly and time-consuming. Simulation technology, as an effective auxiliary tool, can significantly reduce experimental costs, shorten the development cycle, and accurately optimize key performance parameters, thus playing an irreplaceable role in promoting the practical application and technological innovation of high-power fiber lasers.
This study aims to systematically sort out and summarize the research progress of typical high-power fiber laser simulation software, clarify the current research status of this field, and provide practical references for the R&D and application of related simulation software in the industry.
This paper focuses on investigating mainstream high-power fiber laser simulation software at home and abroad, conducts in-depth analysis and comparison of their core functional characteristics, technical advantages, and applicable scenarios, and combs the research ideas and technical routes of high-power fiber laser modeling and simulation.
The study summarizes the main research features of high-power fiber laser modeling and simulation, discusses the key technical points in the effective verification and reliable application of simulation software, and clearly sorts out the latest research progress of typical simulation software.
This paper prospects the future development directions of high-power fiber laser simulation software, including the integration of multi-physics field simulation, high-precision model construction, artificial intelligence-enabled fiber laser design, as well as standardized interfaces and an open-source ecosystem. This study provides valuable theoretical and practical references for the R&D and upgrading of simulation software in related industries.
, Available online , doi: 10.11884/HPLPB202638.250430
Abstract:
Background Purpose Methods Results Conclusions
High-power femtosecond fiber lasers have extensive applications in advanced manufacturing, laser particle acceleration, high-order harmonic generation and so on. Coherent beam combining (CBC) of femtosecond fiber lasers serves as an effective technical approach to overcome the power limitations of single fibers and achieve high-power femtosecond laser output.
This work aims to develop a high-power femtosecond fiber laser CBC system to achieve kilowatt-level average power output with high stability.
The presented femtosecond fiber laser CBC system is based on a three-channel all-fiber chirped pulse amplifier. Phase adjustment and stable coherent combining of three laser amplifiers are achieved using fiber stretchers in combination with the stochastic parallel gradient descent (SPGD) algorithm.
At a total output power of 1219.1 W, the system delivers a combined power of 1072 W, corresponding to a combining efficiency of 87%. The combined beam exhibits near-diffraction-limited beam quality (M2=1.23), and the compressed pulse width is 899 fs. Furthermore, the influence of beam quality degradation on the combining efficiency is theoretically analyzed. The results show that the combining efficiency would decrease as the beam quality degradation rate increased, and the combining efficiency is more sensitive to the degradation of multi-channel beam quality.
The demonstrated all-fiber coherent beam combining system exhibits excellent stability and high-power output. Further power scaling can be realized by increasing the number of combining channels, thereby providing crucial technical support for the advanced applications of high flux ultrafast and ultra-intense lasers.
, Available online , doi: 10.11884/HPLPB202638.250450
Abstract:
Background Purpose Methods Results Conclusions
Unmanned aerial vehicles (UAVs) pose significant military threats and civil security risks, and microwave technology has become a core counter-UAV means due to its low cost, area-effect engagement, and all-weather capability. Research on UAV microwave effects is the foundation for counter-UAV equipment development and protection design.
This paper aims to systematically review the research progress of UAV microwave effects, clarify existing challenges, and provide directional references for future studies.
By combing through domestic and foreign relevant research, this review summarizes the characteristics of different microwave effects, analyzes key influencing factors, and sorts out current research limitations and development trends.
Front-door effects involve coupling through intentional electromagnetic channels (e.g., data links) with low-noise amplifiers as sensitive components, and thresholds are related to frequency matching; back-door effects rely on unintentional channels (e.g., cables, housing gaps) with cables as the main path, but relevant research is insufficient; system-level effects show hierarchical failure, affected by UAV models, microwave parameters, and attitudes. Current research faces “black box” coupling mechanisms, fragmented methods, and inadequate connection with protection design.
Future research should focus on multi-path collaborative coupling modeling, complex scenario assessment, and countermeasure-protection collaborative technologies. This review provides a systematic reference for the field, supporting counter-UAV equipment development and safe UAV application.
, Available online , doi: 10.11884/HPLPB202638.250424
Abstract:
Background Purpose Methods Results Conclusions
Diamond is considered a promising candidate for photoconductive semiconductor switches (PCSSs) due to its exceptional material properties.
However, the development of high-performance diamond PCSSs is primarily impeded by their high on-state resistance and relatively low breakdown voltage. This study aims to improve the performance of the diamond PCSSs.
Passivated with Si3N4, vertical PCSSs were fabricated using nitrogen-doped single-crystal diamonds with different doping concentrations and thicknesses. The doping concentrations of diamond samples were analyzed. The photoresponse of the PCSSs was characterized under 532 nm laser excitation over a range of DC bias voltages.
The experimental results showed that the nitrogen-doped diamond PCSSs present a large on/off ratio (～1011) along with sub-nanosecond rise and fall times. Among them, the diamond PCSS device with the highest nitrogen doping concentration exhibited the minimum on-state resistance. By reducing material thickness, a peak output power of 128 kW was achieved at a bias voltage of 4 kV (corresponding to the electric field strength of 110 kV/cm), with the PCSS exhibiting an on-state resistance of 28.9 Ω, further improving the device performance.
Through the design of nitrogen doping concentration, reduction of substrate thickness, and application of Si3N4 passivation, this work successfully developed diamond PCSSs with good performance, paving the way for the development of high-performance diamond PCSSs.
, Available online , doi: 10.11884/HPLPB202638.250237
Abstract:
Background Purpose Methods Results Conclusions
With the advancement of high-power microwave (HPM) technology, there is a growing demand for HPM antennas with beam scanning capabilities.
This paper focuses on the beam-scanning technology in HPM field and proposes a novel circularly-polarized all-metal beam-scanning lens antenna based on the Risley-prism principle, aiming to address the challenges of wide-angle beam scanning and high power handling capacity (PHC).
By introducing circular slots and metamaterial structures into hexagonal units, a circular polarization orthogonal conversion efficiency(the conversion efficiency of incident left-hand/right-hand circularly polarized (LHCP/RHCP) waves to their orthogonal RHCP/LHCP waves) of over 99% at the central frequency and a continuous phase tuning range of 0° to 360° are achieved. After arraying, the two-layer lens, together with the radial line slot array (RLSA) antenna, constitutes the beam scanning antenna system. Specifically, the first lens converts the circularly polarized hollow beam radiated by the feed antenna into a solid beam while achieving a 25.66° beam deflection synchronously. The second lens further deflects the beam, and two-dimensional beam scanning within a conical angle of ±60° can be realized by independently rotating the two layers of lenses.
A beam scanning lens antenna operating at 14.25 GHz with an axial length of 5.6λ is designed and simulated. During the scanning process, the gain varies within the range of 34.7–37.9 dB, the reflection coefficient remains consistently below −25 dB, and the maximum aperture efficiency exceeds 79%, with the PHC of the beam scanning antenna exceeds 1 GW.
The antenna proposed in this paper exhibits excellent beam scanning performance and high PHC, demonstrating great potential for applications in the HPM field.
, Available online , doi: 10.11884/HPLPB202638.250414
Abstract:
Background Purpose Methods Results Conclusions
The W-band constitutes a critical atmospheric window in the millimeter-wave spectrum, with significant importance for advanced applications such as high-capacity communications, high-resolution imaging, and high-precision sensing. As essential components within core millimeter-wave transmitter and receiver systems, filters fundamentally determine transceiver performance. However, conventional designs frequently face challenges in simultaneously achieving high electrical performance and favorable manufacturability, representing a key obstacle in contemporary W-band filter development.
This work aims to develop a low-loss, low-order, and readily fabricable waveguide quasi-elliptic bandpass filter for the W-band. The goal is to maximize structural simplicity while maintaining high performance, thereby addressing the requirements of next-generation highly-integrated transceiver systems.
The proposed filter employs a novel H-plane offset magnetic coupling configuration, which simplifies the input–output coupling mechanism. Guided by quasi-elliptic filtering theory, transmission zeros are generated on both sides of the passband through the excitation of TE201/TE102 and TE301/TE102 hybrid modes in two respective resonant cavities, resulting in enhanced out-of-band suppression. The filter is implemented in a split-block architecture and fabricated via high-precision computer numerical control (CNC) milling.
Measured results demonstrate an operational passband from 91.5 GHz to 98 GHz, corresponding to a 3 dB fractional bandwidth of 7%, with an in-band insertion loss as low as 0.4 dB and a return loss greater than 15 dB. Except for a slight deviation observed at the upper band edge, the experimental data show strong agreement with simulation, confirming the design’s manufacturability, integration compatibility, and high-frequency performance.
A compact, low-loss W-band quasi-elliptic filter has been successfully realized using only two hybrid-mode cavities. The presented design exhibits notable advantages in terms of fabrication ease, integration suitability, and electrical performance, providing a viable solution for advanced millimeter-wave system applications.
, Available online , doi: 10.11884/HPLPB202638.250297
Abstract:
Background Purpose Methods Results Conclusions
With the rapid development of low-earth orbit (LEO) satellite communications, there is a pressing need for circularly polarized phased arrays that offer wide-angle scanning capability while maintaining a low profile, which remains a significant challenge in current designs.
This study aims to design a low-profile, wide-beam circularly polarized antenna element and its corresponding wide-angle scanning array to address the limitations of narrow scan angles and high profiles in existing solutions.
A double-layer antenna element was designed, utilizing corner perturbation and cross-slots to achieve left-hand circular polarization, while beamwidth was broadened via an upper parasitic structure and metallic posts based on pattern superposition. A 4×4 array was constructed by rotating these elements, with annular open slots integrated into the ground plane to suppress mutual coupling.
The proposed antenna element exhibits a 3-dB axial ratio beamwidth greater than 175°, a gain beamwidth of 120°, and a profile of only 0.07λ0. Simulations of the 4×4 array demonstrate a scan coverage of ±60°, with axial ratio consistently below 2 dB and a stable gain fluctuation of 3.38 dB throughout the scanning range.
The designed antenna and array effectively achieve wide-angle circularly polarized scanning with low profile and stable performance, offering a promising solution for LEO satellite communication terminals and other integrated systems requiring wide spatial coverage.
, Available online , doi: 10.11884/HPLPB202638.250467
Abstract:
Background Purpose Methods Results Conclusions
The projection sequence of Hadamard speckle patterns directly influences the image reconstruction quality and efficiency of Computational Ghost Imaging under undersampled conditions. Optimizing the speckle sorting strategy is an effective approach to achieving high-quality imaging at low sampling rates.
This study aims to address the oscillation of quality metrics observed during the sampling process of traditional sorting strategies and to further enhance the signal-to-noise ratio and convergence stability within the low-sampling-rate regime.
A Recursive Cross (RC) sorting strategy based on the Hadamard basis is proposed. By inversely deconstructing hierarchical subspaces and utilizing an even-index mapping mechanism, this method interleaves and reorganizes speckles with orthogonal texture features, thereby disrupting the continuous accumulation of unidirectional features in the sampling sequence. Numerical simulations under both ideal and gaussian noise environments, along with optical experiments, were conducted to validate the proposed method.
Simulation results demonstrate that the RC strategy effectively eliminates the oscillation of evaluation metrics observed in Russian Dolls sorting as the sampling rate increases across the full 0–100% range, achieving a smooth evolution and robust convergence of imaging quality. Particularly in the low-sampling-rate range of 0–10%, the Peak Signal-to-Noise Ratio of the reconstructed images shows a maximum improvement of approximately 101.7% compared to Hadamard natural sorting and 11.4% compared to Laser Model Speckle sorting, with a maximum gain of about 3.4 dB.
By optimizing the sampling path of spectral energy, the RC sorting strategy improves the data acquisition efficiency of ghost imaging, potentially offering an effective technical pathway for realizing rapid and real-time ghost imaging applications.
, Available online , doi: 10.11884/HPLPB202638.250330
Abstract:
Background Purpose Methods Results Conclusions
With the continuous advancement of photoelectric applications such as LiDAR, three-dimensional sensing, and free-space communication towards longer distances, larger fields of view, and higher precision, large-spot, nanosecond-pulse lasers are progressively emerging as a critical type of light source, owing to their advantages in far-field uniform illumination and weak signal detection.
To address the challenges of amplitude distortion and sampling difficulties in beam quality measurements of large-spot, nanosecond-pulse lasers caused by optical path shaping distortions, transient capture limitations, and coherence requirements, this paper proposes a beam quality measurement system tailored for nanosecond pulsed large-aperture lasers.
The system employs a three-dimensional stepping platform combined with a photodetector to reconstruct the spatial intensity distribution of the beam, and incorporates a multi-channel peak-hold circuit to accurately latch pulse peaks, thereby ensuring transient fidelity in amplitude acquisition. To mitigate non-ideal conditions such as partial beam truncation and incomplete boundaries, a circle-fitting method is introduced as a complement to the second-moment calculation of energy, enhancing the robustness of beam size evaluation.
Experiments employing a typical vertical-cavity surface-emitting laser (VCSEL) were conducted through multi-position 3D axial scanning, comparing the consistency of beam size and energy distribution measured by different methods.
The results verify the measurement reliability and applicability of the proposed system under large-spot, nanosecond-pulse conditions, offering an effective means for laser beam quality assessment in related applications.
, Available online , doi: 10.11884/HPLPB202638.250245
Abstract:
Background Purpose Methods Results Conclusions
Neutron multiplicity measurement technology, as a core method in the field of non-destructive testing, plays a critical role in determining the mass of fissionable material (235U). However, it suffers from technical bottlenecks such as prolonged measurement cycles and measurement deviations under non-ideal conditions.
This paper aims to explore feasible pathways for integrating neutron multiplicity measurement methods with neural network technology. The goal is to provide new research perspectives for advancing neutron multiplicity measurement technology toward greater efficiency and intelligence.
Leveraging Geant4 and MATLAB software, an Active Well Coincidence Counter (AWCC) simulation model is constructed to achieve high-precision simulation of the entire active neutron multiplicity measurement process. Building upon this, three neural networks—Backpropagation Neural Network (BPNN), Convolutional Neural Network (CNN), and Long Short-Term Memory network (LSTM)—are developed using the PyTorch framework to analyze and investigate neutron multiplicity distribution data.
Compared with traditional calculation methods based on the active neutron multiplicity equation, neural network models represented by CNN and LSTM demonstrate significant advantages in measurement accuracy and efficiency. Specifically, in terms of relative error metrics, neural network models can reduce errors to lower levels; in the time dimension of measurement, they substantially shorten data processing cycles, effectively overcoming the timeliness constraints inherent to traditional approaches.
This achievement fully validates the theoretical feasibility and technical superiority of the neural network-based neutron multiplicity measurement approach, providing a novel solution for advancing neutron multiplicity detection toward greater efficiency and intelligence. Subsequent work will enhance the adaptability and noise resistance of neural network models for complex data by increasing simulation scenario complexity and introducing diversified factors such as noise interference and geometric variations. Meanwhile, building upon simulation studies, physical experimental validation will be conducted using AWCC instrumentation to drive the transition of neural network-based neutron multiplicity measurement technology from simulation to engineering application.
, Available online , doi: 10.11884/HPLPB202638.250298
Abstract:
Background Purpose Methods Results Conclusions
The reaction kinetics in lasers often involves a lots of excited state species. The mutual effects and numerical stiffness arising from the excited state species pose significant challenges in numerical simulations of lasers. The development of artificial intelligence has made Neural Networks (NNs) a promising approach to address the computational intensity and instability in Excited State Reaction Kinetics (ESRK).
However, the complexity of ESRK poses challenges for NN training. These reactions involve numerous species and mutual effects, resulting in a high-dimensional variable space. This demands that the NN possess the capability to establish complex mapping relationships. Moreover, the significant change in state before and after the reaction leads to a broad variable space coverage, which amplifies the demand for NN's accuracy.
To address the aforementioned challenges, this study introduces the successful sequence-to-sequence learning from large language learning into ESRK to enhance prediction accuracy in complex, high-dimensional regression. Additionally, a statistical regularization method is proposed to improve the diversity of the outputs. NNs with different architectures were trained using randomly sampled data, and their capabilities were compared and analyzed.
The proposed method is validated using a vibrational reaction mechanism for hydrogen fluoride, which involves 16 species and 137 reactions. The results demonstrate that the sequential model achieves lower training loss and relative error during training. Furthermore, experiments with different hyperparameters reveal that variation in the random seed can significantly impact model performance.
In this work, the introduction of the sequential model successfully reduced the parameter count of the conventional wide model without compromising accuracy. However, due to the intrinsic complexity of ESRK, there remains considerable room for improvement in NN-based regression tasks for this domain.
, Available online , doi: 10.11884/HPLPB202638.250392
Abstract:
Background Purpose Methods Results Conclusions
Typically, radiation detectors require an additional coupled scintillator layer to convert incident radiation rays into optical signals, which are then received by the detector. Compared to other types of glass, lead fluoride (PbF2) glass has a high refractive index, and when electrons pass through a lead fluoride crystal, they generate Cherenkov light. As a result, lead fluoride itself can function as a scintillator.
Using a lead fluoride crystal as the optical window of a detector enables it to both generate and detect light. This optimizes the optical transmission and detection performance, shortens the conversion time from the reaction medium to photons, improves the detector’s efficiency, and provides an experimental foundation for future applications in ultrafast detection.
After cleaning components such as the cathode input window, ceramic parts, and anode of the photomultiplier tube, a transition indium sealing film layer is deposited on the cathode input window. The ceramic and metal components are then sealed and assembled into a tube shell using a hydrogen furnace. Indium sealing solder is melted into the tube shell’s indium sealing groove, and the tube shell is laser-welded to the anode. The processed tube shell, microchannel plate (MCP), and anode are assembled according to the designed structure. After assembly, the tube shell components and cathode window are mounted on a transfer-type cathode activation and exhaust station. Cathode activation and MCP electron scrubbing processes are then performed. Upon completion of these steps, the tube shell and cathode window are sealed together using indium sealing, resulting in the fabrication of an MCP-type photomultiplier tube bare tube.
Two PbF2-window MCP-PMTs were successfully prepared, and their electrical performance, including quantum efficiency and operating voltage, can be measured.
By integrating lead fluoride crystals, fast-time-response microchannel plates, and a fast-time coaxial conical anode, this study has successfully addressed key technical challenges in the preparation of lead fluoride crystals as the optical window for photomultiplier tubes. Post-fabrication performance tests indicate that core parameters such as quantum efficiency, gain, and rise time are generally comparable to those of conventional fast-time-response MCP-PMTs.
, Available online , doi: 10.11884/HPLPB202638.250346
Abstract:
In indirect-drive laser inertial confinement fusion (ICF), the precise calculation of X-ray drive intensity at the capsule is crucial for accurately predicting the implosion performance of deuterium-tritium fuel capsules. Achieving this requires detailed radiation-hydrodynamic simulations that accurately capture processes such as laser-to-X-ray conversion and X-ray absorption losses at the hohlraum walls. However, since the inception of the National Ignition Campaign at the National Ignition Facility (NIF), radiation-hydrodynamic simulations have consistently overestimated the experimentally measured X-ray drive flux intensity at the capsule, reflecting the widespread presence of hohlraum energy deficits. Although extensive experimental studies have been conducted at NIF along with continuous optimization of its radiation-hydrodynamic simulation models, the challenging issue of hohlraum energy deficit remains unresolved, constituting one of the critical barriers to achieving high-gain inertial confinement fusion. This paper systematically reviews the critical research developments regarding hohlraum energy deficit at NIF and introduces the methods adopted by NIF and China for characterizing the X-ray radiation flux intensity at the capsule.
In indirect-drive laser inertial confinement fusion (ICF), the precise calculation of X-ray drive intensity at the capsule is crucial for accurately predicting the implosion performance of deuterium-tritium fuel capsules. Achieving this requires detailed radiation-hydrodynamic simulations that accurately capture processes such as laser-to-X-ray conversion and X-ray absorption losses at the hohlraum walls. However, since the inception of the National Ignition Campaign at the National Ignition Facility (NIF), radiation-hydrodynamic simulations have consistently overestimated the experimentally measured X-ray drive flux intensity at the capsule, reflecting the widespread presence of hohlraum energy deficits. Although extensive experimental studies have been conducted at NIF along with continuous optimization of its radiation-hydrodynamic simulation models, the challenging issue of hohlraum energy deficit remains unresolved, constituting one of the critical barriers to achieving high-gain inertial confinement fusion. This paper systematically reviews the critical research developments regarding hohlraum energy deficit at NIF and introduces the methods adopted by NIF and China for characterizing the X-ray radiation flux intensity at the capsule.
, Available online , doi: 10.11884/HPLPB202638.250403
Abstract:
This paper focuses on the element doping technology of low-density polymer foams for inertial confinement fusion (ICF) experiments and summarizes their research status and development trends. As key target materials for ICF, low-density polymer foams can optimize radiation transport, suppress hydrodynamic instability, and achieve diagnostic functions by introducing doping elements such as chlorine, argon, and germanium. The paper systematically analyzes the principles, advantages, disadvantages, and application bottlenecks of two major types of technologies: physical doping (particle dispersion, physical vapor deposition) and chemical doping (copolymerization, monomer functionalization, polymer substitution), with an emphasis on core issues such as uniformity control and doping precision. Finally, it looks forward to cutting-edge directions including composite doping, two-photon polymerization, and ion implantation, providing technical references for the high-performance and precise preparation of ICF target materials and facilitating the development of high-repetition-rate ICF experiments.
This paper focuses on the element doping technology of low-density polymer foams for inertial confinement fusion (ICF) experiments and summarizes their research status and development trends. As key target materials for ICF, low-density polymer foams can optimize radiation transport, suppress hydrodynamic instability, and achieve diagnostic functions by introducing doping elements such as chlorine, argon, and germanium. The paper systematically analyzes the principles, advantages, disadvantages, and application bottlenecks of two major types of technologies: physical doping (particle dispersion, physical vapor deposition) and chemical doping (copolymerization, monomer functionalization, polymer substitution), with an emphasis on core issues such as uniformity control and doping precision. Finally, it looks forward to cutting-edge directions including composite doping, two-photon polymerization, and ion implantation, providing technical references for the high-performance and precise preparation of ICF target materials and facilitating the development of high-repetition-rate ICF experiments.
, Available online , doi: 10.11884/HPLPB202638.250242
Abstract:
Background Purpose Methods Results Conclusions
Precise γ-ray spectrum analysis is essential for nuclide identification and activity quantification, but faces significant challenges when using low-resolution detectors such as CLYC scintillators in complex radiation fields. The limited energy resolution of these detectors often leads to overlapping peaks and obscured characteristic spectral features, which complicates accurate spectrum interpretation.
This study aims to overcome the inherent energy resolution limitations of CLYC detectors by developing a spectrum deconvolution method that can recover clear spectral information and separate overlapping peaks in complex γ-ray spectra.
A detector energy response matrix was constructed by combining Monte Carlo simulations to calculate γ-ray energy response functions with an interpolation method. Response functions were derived across the 0～3 MeV energy range at intervals of 0.05 MeV to ensure high precision. Spectrum deconvolution was then performed using the Maximum Likelihood Expectation Maximization (MLEM) algorithm, which was then applied to analyze the original complex spectrum.
The method was validated by unfolding the spectra of a 226Ra source, a mixed 60Co - 137Cs source, and the complex spectrum of 152Eu. The unfolded spectrum exhibited well-resolved characteristic peaks, effective separation of severely overlapping spectral regions, and stable quantitative results for characteristic peak areas.
The proposed approach significantly enhances the precision of γ-ray spectrum analysis with CLYC detectors. It successfully reveals the energy and intensity information of incident γ-rays, mitigates the detector’s resolution limitations, and provides a reliable method for analyzing spectrum in complex radiation environment.
, Available online , doi: 10.11884/HPLPB202638.250281
Abstract:
Background Purpose Method Results Conclusions
When using the Monte Carlo method for radiation shielding simulations, the efficiency is low. Employing specific variance reduction techniques is one of the methods to accelerate radiation shielding simulations, while another more universal approach is to use large-scale parallel technology to enhance the simulation speed from the hardware aspect. At present, due to the enormous demand for computing power triggered by the development of artificial intelligence technology, major supercomputing platforms have steadily improved their support for large-scale GPU parallel architectures. To adapt to the current and future GPU parallel architectures of supercomputing platforms, it is necessary to develop Monte Carlo transport algorithms suitable for GPU platforms.
This paper aims to accelerate fixed-source calculation of the NECP-MCX Monte Carlo particle transport code by utilizing GPU parallel, thereby enhancing the efficiency of radiation shielding transport simulations.
This paper analyzes the characteristics of the GPU event-based parallel algorithm under the fixed-source mode. The GPU event-based parallel algorithm has been preliminarily implemented within the NECP-MCX code and was tested and analyzed using a simple fixed-source problem.
The results show that the maximum number of simultaneous simulated events is positively correlated with the simulation speed. Sorting particle information can accelerate the simulation by 28%, and the GPU parallel implementation is 25 times faster than the single-core CPU implementation.
The initial implementation shows significant potential for acceleration; however, further research is essential to fully exploit its capabilities and optimize performance.
, Available online , doi: 10.11884/HPLPB202638.250378
Abstract:
Background Purpose Methods Results Conclusions
High-fidelity neutronics simulation of nuclear reactor cores, particularly those with complex geometries such as the AP1000, remains computationally challenging. Efficient deterministic methods that can achieve Monte Carlo-level accuracy are highly desirable for design and analysis.
This study aims to develop, apply, and validate the FLASH code, which implements an advanced Fission Response Function (FRF) algorithm, for performing efficient and accurate full-core, pin-wise neutronics calculations of the AP1000 reactor core.
The FRF database was generated through reference-state simulations using the Serpent Monte Carlo code. To enhance accuracy in complex geometries, the methodology incorporated a local inter-assembly environmental correction factor to address fuel assembly heterogeneity and a predictor-corrector scheme to precisely simulate reflector environmental effects. The performance of the FLASH code was validated against reference Monte Carlo solutions under Hot Zero Power (HZP) conditions.
The validation results demonstrated high accuracy. Deviations in the effective multiplication factor (keff) were within +220 pcm for all 2D axial slices and +209 pcm for the full 3D core calculation. The root-mean-square error (RMSE) was below 1.1% for the 2D pin power distribution, while the 3D pin power RMSE was 1.05% and the 3D assembly power RMSE was 0.67%. In terms of efficiency, the FLASH code completed the pin-wise full-core 3D calculation for the AP1000 in 106 seconds using 64 CPU cores.
The developed FLASH code, based on the FRF algorithm with integrated correction schemes, successfully bridges the gap between efficiency and high fidelity. It provides a rapid and accurate computational tool for AP1000 core analysis, confirming the practicality and effectiveness of the proposed methodology for detailed reactor physics calculations.
, Available online , doi: 10.11884/HPLPB202638.250168
Abstract:
Background Purpose Methods Results Conclusions
Gamma and thermal neutron imaging are important non-destructive testing methods, which are complementary in many aspects. The thermal neutron and Gamma bimodal imaging can combine the advantages of both. Compares with single beam imaging, the bimodal imaging has the ability to identify different substances and the sensitivity to both nuclides and elements simultaneous.
Utilizing the reaction between protons and target material producing neutrons and Gamma together, based on the 18 MeV cyclotron accelerator being developed by the Institute of Atomic Energy, this paper designs a bimodal imaging neutron source by simulation.
Beryllium with a high （p, n） reaction cross-section is selected as the neutron target to generate neutrons. To obtain thermal neutrons with higher flux, polyethylene is used as the neutron moderator and reflector. By the different spatial distributions of thermal neutrons and Gamma, these two types of radiation are separately extracted from different directions. Besides, by designing the neutron and Gamma exits on polyethylene, high neutron flux and Gamma beams are simultaneously obtained.
After simulation optimization, the thermal neutron flux at the thermal neutron outlet can reach 1.78×1010 n/（cm2·s） , and the gamma dose at the gamma outlet can reach 2.23×104 rad/h.
This paper design a neutron source for thermal-neutron-gamma imaging based on the 18 MeV/1 mA cyclotron accelerator. The design efficiently extracts thermal neutron flux and gamma flux from a single target, implementing a single-target-dual-source configuration.
, Available online , doi: 10.11884/HPLPB202638.250291
Abstract:
Background Purpose Methods Results Conclusions
Boron Neutron Capture Therapy (BNCT) is an innovative binary targeted cancer treatment technology with high relative biological effect and cell-scale precision, but its clinical application is limited by the long computation time of traditional Monte Carlo methods for dose calculation and insufficient dosimetric research on head tumors.
This study aims to address these challenges by optimizing the Monte Carlo algorithm and developing pre-processing/post-processing modules, verifying the accuracy of the computational system, and analyzing the dosimetric characteristics of BNCT for head tumors.
Based on NECP-MCX, three acceleration strategies voxel geometry fast tracking, transport-counting integration, MPI parallel optimization were adopted to improve computational efficiency. Pre-processing (DICOM image parsing, material-boron concentration mapping, 3D voxel modeling) and post-processing (dose-depth curve, Dose-Volume Histogram (DVH), dose distribution cloud map) modules were developed. Both NECP-MCX and MCNP were used to calculate the dose distribution of a head tumor case (RADCURE-700) for comparison.
The single-dose calculation time was reduced from 2 hours to 9.4 minutes. The dose curves, DVH, and cloud maps from the two programs showed good consistency with relative deviations below 5% within 10 cm depth. BNCT achieved a tumor target volume D90 of 60 Gy in 63 minutes, with healthy tissue dose below 12.5 Gy.
The optimized NECP-MCX system realizes efficient and accurate dose calculation for BNCT. The consistent results validate its reliability, and the dosimetric analysis demonstrates BNCT’s potential for head tumor treatment, providing methodological support for clinical treatment planning.
, Available online , doi: 10.11884/HPLPB202638.250386
Abstract:
This paper briefly reviews the series of work carried out by the research team from the Laser Fusion Research Center, China Academy of Engineering Physics, based on the Xingguang-III and Shenguang-II Upgrade laser facilities, in the field of laser-driven neutron source generation and applications. In terms of generation mechanisms, it highlights explorations of several technical approaches, including enhancing photo-nuclear neutron production efficiency through novel target design, increasing neutron yield based on the target normal sheath acceleration mechanism, and obtaining high-quality neutron sources via collisionless electrostatic shock acceleration. On the application front, preliminary experimental studies have been conducted in areas such as fast neutron radiography, material radiation effects, and nuclear material detection, demonstrating the potential application value of such neutron sources as short-pulse, high-flux sources. With continuous advancements in laser technology and ongoing optimization of generation mechanisms, this new type of neutron source is expected to play an increasingly important role in basic scientific research, nuclear energy technology development, and industrial applications, providing new research tools and technical support for the development of related disciplines.
This paper briefly reviews the series of work carried out by the research team from the Laser Fusion Research Center, China Academy of Engineering Physics, based on the Xingguang-III and Shenguang-II Upgrade laser facilities, in the field of laser-driven neutron source generation and applications. In terms of generation mechanisms, it highlights explorations of several technical approaches, including enhancing photo-nuclear neutron production efficiency through novel target design, increasing neutron yield based on the target normal sheath acceleration mechanism, and obtaining high-quality neutron sources via collisionless electrostatic shock acceleration. On the application front, preliminary experimental studies have been conducted in areas such as fast neutron radiography, material radiation effects, and nuclear material detection, demonstrating the potential application value of such neutron sources as short-pulse, high-flux sources. With continuous advancements in laser technology and ongoing optimization of generation mechanisms, this new type of neutron source is expected to play an increasingly important role in basic scientific research, nuclear energy technology development, and industrial applications, providing new research tools and technical support for the development of related disciplines.
, Available online , doi: 10.11884/HPLPB202638.250282
Abstract:
Background Purpose Methods Results Conclusion
The China Institute of Atomic Energy has designed of a 9.5 MeV ultra-compact cyclotron to support the independent of Positron Emission Tomography (PET) cyclotrons. A high-performance control system is critical for the equipment, as the stability of the acceleration field directly impacts beam quality.
In order to ensure the stable acceleration of the accelerator beam, this study aims to develop a Low-Level Radio Frequency (LLRF) control algorithm based on a fully digital hardware platform.
To enhance control precision and increase the feedback rate, a high-speed Digital Down-Conversion(DDC) demodulation system was designed. Addressing the issue where the IQ sequence after digital down-conversion may be distributed in arbitrary quadrants, an innovative quadrant preprocessing module was developed to extend applicability across the Cartesian plane. A position-type Proportion-Integral-Derivative (PID) tuning loop was implemented for automatic frequency compensation, integrating adaptive protection, timed detection, and one-click startup. Furthermore,a robust cross-clock-domain data path is constructed to ensure accurate and stable amplitude regulation.
Closed-loop tests verified the reliability of the demodulation system. During the joint commissioning with the accelerator, a stable internal target beam current of 100 μA was successfully extracted. The system achieved a cavity voltage amplitude stability of 0.047% (RMSE) and maintained a detuning angle of 0.46°(RMSE).
The experimental results demonstrate that the proposed LLRF system fully meets the control requirements of the accelerator. The design ensures high stability and precision, providing reliable technical support for the operation of the 9.5 MeV ultra-compact cyclotron.
, Available online , doi: 10.11884/HPLPB202638.250347
Abstract:
Background Purpose Methods Results Conclusions
Gigahertz-repetition-rate femtosecond fiber lasers have attracted increasing attention for applications requiring high temporal resolution and high average power, while most existing GHz fiber amplification systems are limited to fixed repetition rates.
This work aims to realize repetition-rate-tunable amplification of gigahertz femtosecond pulses within a single fiber-based platform by employing a passively harmonic mode-locked fiber laser as the seed source.
The seed laser provides stable pulse operation with repetition rates tunable from 1 to 3 GHz. A two-stage fiber amplification scheme combined with dispersion management is implemented to maintain stable amplification over the entire tuning range. In the pre-amplification stage, controllable chirp is introduced to achieve near-linear temporal broadening, which effectively suppresses excessive nonlinear effects during power scaling. Pulse compression is subsequently implemented at the output using single-mode fiber.
Experimental results show that stable pulse trains with regular temporal distribution are preserved throughout the tuning range. The maximum average output power reaches 2.1 W at a repetition rate of 3.1 GHz, while the shortest pulse duration of 195 fs is obtained at 2.0 GHz. After amplification, the side-mode suppression ratio remains higher than 33 dB.
These results indicate the feasibility of gigahertz repetition-rate-tunable amplification of femtosecond fiber lasers on a single all-fiber platform.
