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, Available online , doi: 10.11884/HPLPB202638.250239
Abstract:
Background Purpose Methods Results Conclusions
Portable alpha-associated deuterium-tritium (DT) neutron generators have extensive application potential in fields such as nuclear physics experiments, homeland security, and nuclear safeguards and assay.
To evaluate the correlated neutron distribution characteristics of a domestically developed compact portable alpha-associated DT neutron generator, providing critical technical support for its design validation, manufacturing quality control, and engineering applications.
A specialized measurement system was established, comprised of a liquid scintillator detector, a high precision displacement mechanics, and a coincidence measurement digitizer. This system was used to quantify the spatial extent of the correlated neutron emission region and the corresponding solid angle coefficients.
Experimental measurements on two neutron generators revealed a measurable difference in their correlated neutron distribution areas, with an approximate 15% variation in the effective correlation region.
This study provides essential technical support for both the design validation and quality control testing in the manufacturing of this type of compact portable neutron generator. It also offers valuable reference data for engineering applications by end-users.
, Available online , doi: 10.11884/HPLPB202638.250393
Abstract:
Background Purpose Methods Results Conclusions
The retention and diffusion of helium on the surface of the first wall is one of the key problems in the study of magnetic confinement fusion. And laser-induced breakdown spectroscopy is the most promising technique for in-situ diagnosis of the first wall. Compared with the optical spectral range, laser-induced extreme ultraviolet spectra has more advantages in sensitivity, noise suppression and accuracy.
In order to meet the requirement of high precision on-site measurement of helium impurity lines in magnetic confinement fusion, a ultra-high resolution EUV spectroscopy system was developed.
The grazing incidence Czerny-Turner structure is used in the spectrometer, and the luminous flux and spectral resolution are adjusted through an adjustable incidence slit. The ray tracing simulation is carried out with a self-developed optical design software. And the wavelength calibration and performance testing are carried out by microwave plasma light source.
The simulation results show that the spectral resolution is better than 20 000, and the experimental results indicate that the spectrometer achieves a spectral resolution of 0.001 4 nm at He II (30.3786 nm).
The spectrometer can meet the requirement of high-precision measurement of helium extreme ultraviolet spectral lines, and it is expected to provide an important theoretical support for the research on the helium retention and diffusion in the first wall.
, Available online , doi: 10.11884/HPLPB202638.250219
Abstract:
Background Purpose Method Results Conclusions
With the continuous development of nuclear power technology, reactor design has put forward higher requirements for the accuracy, efficiency and multi-functionality of nuclear computing software. The current mainstream Monte Carlo software has deficiencies in the balance between reactor radiation shielding design and nuclear design calibration, which restricts the critical simulation efficiency of the reactor core. Therefore, CNPRI has specifically developed the 3D Monte Carlo software LARCH 1.0 to meet the actual needs of nuclear power engineering design.
To optimize the particle energy search mechanism in Monte Carlo simulation and address the pain point of low efficiency in traditional search methods; Thirdly, based on the optimized search method, the delta-tracking algorithm is further improved to enhance the efficiency of core critical calculation and provide efficient and accurate calculation support for reactor design.
During the development of the LARCH software, the core technological innovation lies in the adoption of a unified energy grid design to replace the traditional binary search and logarithmic search methods. Through the standardization and unification of the energy grid, the number of searches in the particle energy matching process is reduced, and the time consumption of a single search is shortened. Based on the technology of unified energy grid, further develop and optimize the delta-tracking algorithm to achieve the improvement of computing efficiency; By designing a targeted numerical verification scheme, the LARCH 1.0 software and the traditional Monte Carlo software were compared and tested in the reactor problem simulation.
The optimized technical solution has achieved remarkable results. The search method based on the unified energy grid has significantly reduced the time cost of particle energy search compared with the traditional method. Based on this, the optimized delta-tracking algorithm has increased the critical computing efficiency of the Monka software core by approximately 25%.
The unified energy grid method and the optimized delta-tracking algorithm adopted by the LARCH 1.0 3D Monte Carlo software provide an effective technical path for the efficiency improvement of the Monte Carlo software and significantly enhance the critical computing efficiency of the reactor core. The application potential of this software indicates that it can provide more efficient and reliable numerical simulation tools for reactor design. Subsequently, more extensive engineering verification and functional iterations will be further carried out.
, 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/HPLPB202638.250290
Abstract:
Background Purpose Methods Results Conclusions
As an advanced composite material widely used in the aerospace field, carbon fiber reinforced polymer (CFRP) is subjected to extreme service environments characterized by high heat flux and high mechanical loads. Its thermal ablation and high-temperature failure processes are significantly influenced by environmental conditions. Although numerical and experimental studies on the ablation behavior of CFRP have been extensively conducted, systematic experimental research and experimental-simulation comparisons for the ablation behavior of plain-woven CFRP under vacuum environment remain lacking.
This study aims to conduct laser ablation experiments on plain-woven CFRP in a vacuum environment and to establish corresponding theoretical and numerical models of thermal ablation. The work seeks to reveal the internal heat transfer characteristics and the evolution mechanism of ablation damage, thereby providing theoretical and data support for the design and application of composite materials under vacuum or rarefied gas environments.
Experimentally, laser was used as the heat source to design and perform thermal ablation tests on plain-woven CFRP under vacuum. An experimental system based on infrared and thermocouple temperature measurements was employed to record the transient temperature field on the irradiated surface and the temperature of the back surface. In terms of simulation, based on a fiber-yarn/matrix dual-phase micro-modeling strategy and combined with a finite element thermal analysis module and user-defined subroutines, a theoretical and numerical model for the thermal ablation of woven composites was developed.
Experimental results show that no open flame combustion occurred in the composite under vacuum. The epoxy resin matrix underwent significant thermal decomposition and mass loss, while the morphology and structure of the carbon fibers remained intact. The established numerical model relatively accurately simulated the ablation temperature field and ablation morphology, achieving the simulation of the dynamic ablation process including resin decomposition and fiber exposure.
The vacuum environment significantly alters the laser ablation characteristics and final morphology of plain-woven CFRP. Due to the higher energy deposition rate of the laser in the material, a more pronounced heat accumulation effect is induced. The numerical simulation results agree well with the experimental data, verifying the reliability of the model. This study provides an effective analytical tool and theoretical basis for the thermal safety assessment and functional design of woven CFRP in extreme service environments.
, Available online , doi: 10.11884/HPLPB202638.250310
Abstract:
Background Purpose Methods Results Conclusions
Fiber lasers have been widely used in numerous fields such as industrial processing and scientific research detection, due to their significant advantages including high efficiency, low cost, and miniaturization. In the R&D (Research and Development) and mass production of fiber lasers, the synchronous testing of core performance indicators such as power, spectrum, time-domain characteristics, and beam quality is a key technical support. It enables comprehensive evaluation of the device’s overall performance, accurate localization of design defects, optimization of production process parameters, and guarantee of consistent product delivery. However, the traditional testing mode requires temporarily building a dedicated test system for each laser under test. It has problems such as long time consumption, cumbersome operation, and low testing efficiency, making it difficult to meet the needs of large-scale production and high-efficiency R&D.
To address the above issues, this paper proposes an integrated synchronous testing system for multi-parameter fiber lasers. The system aims to realize the synchronous acquisition and testing of multiple indicators, including power, spectrum, time-domain characteristics, and beam quality. It further improves the scientificity of the comprehensive performance evaluation of lasers, provides reliable technical support for production practice and scientific research in related fields, and achieves the core goals of improving testing efficiency and simplifying testing processes.
The system achieves the integrated integration of multi-module hardware testing equipment, as well as standardized interfaces and external connections, based on optical principle design and precision mechanical structure design. From the perspective of safe operation, an emergency shutdown device for abnormal working conditions is equipped to ensure the safety of the system and the laser under test during the testing process. The control software adopts LabVIEW multi-threading technology to realize the synchronous acquisition and real-time transmission of various parameters.
The system can adapt to the testing needs of fiber lasers with an output power range of 80 W to 10 kW. During testing, users only need to connect the fiber end cap of the laser under test to the system, and can start multi-parameter synchronous testing through the upper computer software without manual intervention in the optical adjustment link. After the test, the system can automatically complete the analysis and processing of raw data and generate a standardized test report. Verification experiments conducted with a 10 kW fiber laser as the test object show that the system has good operability, reliability, test repeatability, and technical feasibility.
The system significantly improves the efficiency of multi-parameter testing of fiber lasers and greatly reduces the complexity of data processing, providing an efficient and reliable solution for scientific research and industrial laser testing.
, Available online , doi: 10.11884/HPLPB202638.250382
Abstract:
Background Purpose Methods Results Conclusions
Ultrashort and ultraintense laser-driven plasma X-ray sources offer femtosecond pulse durations, intrinsic spatiotemporal synchronization, compactness, and cost-effectiveness, serving as an important complement to traditional large-scale light sources and providing novel experimental tools for ultrafast dynamics research.
Built upon the Synthetic Extreme Condition Facility (SECUF), the first open-access user experimental station in China based on high-power femtosecond lasers was established to deliver various types of ultrafast radiation sources, supporting studies on ultrafast material dynamics and frontier strong-field physics.
The station is equipped with a dual-beam titanium-sapphire laser system (3 TW/100 Hz and PW/1 shot/min) and multiple beamlines with multifunctional target chambers. Through interactions between the laser and solid targets, gas targets, or plasmas, various ultrafast light sources—such as Kα X-rays, Betatron radiation, and inverse Compton scattering—are generated. Platforms for strong-field terahertz pump–X-ray probe (TPXP) experiments and tabletop epithermal neutron resonance spectroscopy have also been developed.
A highly stable ultrafast X-ray diffraction and TPXP platform was successfully established, enabling direct observation of strong-field terahertz-induced phase transition in VO2. The world’s first tabletop high-resolution epithermal neutron resonance spectroscopy device was developed. On the PW beamline, hundred-millijoule-level intense terahertz radiation, efficient inverse Compton scattering, and high-charge electron beams were achieved.
Integrating high-performance lasers, diverse radiation sources, and advanced diagnostic platforms, this experimental station provides a flexible and efficient comprehensive facility for ultrafast science, promising to advance ultrafast dynamics research toward broader accessibility and more cutting-edge directions.
, Available online , doi: 10.11884/HPLPB202638.250164
Abstract:
Background Purpose Methods Results Conclusions
Cancer is a major global health issue. With the development of accelerator physics, boron neutron capture therapy based on accelerator neutron sources has received widespread attention. In the accelerator system, the low energy beam transport is responsible for connecting the ion source and accelerator, as well as processing the beam. For the problem of beam deflection, the chopper is required, so a high-performance chopper is crucial for the entire system.
This study aims to improve the electric field uniformity of the chopper by using circular arc plates instead of parallel plates, and to simulate the chopper design through Python program coupling using CST studio suite and Tracewin software.
The beam deflection formula of the chopper was theoretically derived, and the electrostatic and beam dynamics design was completed through CST studio suite and Tracewin software. The advantages and feasibility of the circular arc plate were verified through coupling simulation of the two software.
Theoretical calculations and simulations have shown that the electric field distribution of circular arc plates is more uniform, and the beam deflection function is efficiently completed, confirming the feasibility of the design scheme.
By coupling CST studio suite with Tracewin software for simulation, a more realistic simulation of beam dynamics can be achieved, which solves the problem of Tracewin software being unable to set the electric field strength of circular arc plates. The joint simulation method of CST studio suite and Tracewin has been developed, which has certain value for research on chopper design.
, 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.
