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2026 Volume 38 Issue 4  Published: 2026-04-15
    High Power Laser Physics and Technology
  • Xintao Li , Hui Liu , Shuo Qiao , Yifan Yang , Yang Lv , Xia Liu , Lingling Xiong
    doi: 10.11884/HPLPB202638.250370
    Background

    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.

    Purpose

    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.

    Methods

    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.

    Results

    In theoretical simulations, SMI signals with 10 dB noise were input into the trained CNN, resulting in a displacement reconstruction RMSE of 5.3 × 108. In experimental tests, SMI signals containing system noise were processed by the network, yielding a reconstructed displacement RMSE of 2.1 × 107. The simulation and experimental results demonstrate consistent performance.

    Conclusions

    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.

  • High Power Laser Physics and Technology
  • Xinyu Li , Yimin Mao , Zhao Zhang , Qing Xu , Xiang Lu , Fang Ren
    doi: 10.11884/HPLPB202638.250301
    Background

    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.

    Purpose

    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.

    Methods

    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 achieved through 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.

    Results

    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.

    Conclusions

    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.

  • High Power Laser Physics and Technology
  • Qing Tang , Luwei Liu , Wei Li , Qiang Yu , Wentong Sun , Kai Wang
    doi: 10.11884/HPLPB202638.250270
    Background

    Although quartz exhibits excellent light transmittance, the significant difference in thermal expansion coefficients between quartz and metal sealing materials has long been a critical technical bottleneck, leading to interface stress concentration and vacuum sealing failures in low-leakage quartz windows.

    Purpose

    This study addresses the urgent demand for ultra-high vacuum precision optical systems by conducting systematic research on sealing technologies for high-performance quartz vacuum windows.

    Methods

    To overcome this challenge, this paper innovatively proposes using magnetron sputtering technology to sequentially deposit a Ti/Mo/Cu/Ag multilayer film system on the quartz welding surface, thereby creating a gradient functional metallization layer with thermal stress buffering capability that achieves effective surface metallization.

    Results

    Scanning electron microscopy observations revealed continuous, dense, and structurally uniform film layers. Nanoindentation experiments further demonstrated a bonding strength of approximately 3.83 N between the metallized layer and quartz substrate, indicating robust adhesion. Experimental results show that vacuum window components fabricated using this metallization scheme achieve leakage rates below 1012 Pa·L/s.

    Conclusions

    This achievement has broad applications in synchrotron radiation, quantum measurement, and space exploration, providing crucial technical support for the development of high-performance vacuum devices.

  • High Power Laser Physics and Technology
  • Lei Yang , Zheng Huang , Li Sun , Feng Lu , Yong Chen , Gang Li , Kainan Zhou
    doi: 10.11884/HPLPB202638.250303
    Background

    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.

    Purpose

    This study aims to develop an X-ray online-aiming pinhole camera for the Xingguang-Ⅲ laser facility to address the challenge of precise target alignment under vacuum conditions and enhance the reliability of signal acquisition.

    Methods

    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.

    Results

    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.

    Conclusions

    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.

  • High Power Laser Physics and Technology
  • Kaihua Wang , Huanyu Yang , Siming Li , Cheng Guo , Qing Zhao
    doi: 10.11884/HPLPB202638.250439
    Background

    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 deployments.

    Purpose

    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.

    Methods

    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.

    Results

    The simulations showed stable transmission above 90% across the 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.

    Conclusions

    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 require both electromagnetic transparency and structural compatibility.

  • Inertial Confinement Fusion Physics and Technology
  • Xuelong Qin , Hang Zhao , Qi Li , Kaiqiang Pan , Yaoyuan Liu , Sanwei Li , Lu Zhang , Dong Yang , Tao Gong , Zhichao Li
    doi: 10.11884/HPLPB202638.250346

    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.

  • Inertial Confinement Fusion Physics and Technology
  • Baolong Shi , Xiuwen Zhou , Lianghong Yan , Weiren Wang , Haijun Zhang
    doi: 10.11884/HPLPB202638.250403

    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 doping 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 discusses 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.

  • High Power Microwave Technology
  • Jiaxin Liu , Yike Guo , Fangwei Li , Qinggong Guo
    doi: 10.11884/HPLPB202638.250297
    Background

    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.

    Purpose

    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.

    Methods

    A double-layer antenna element was designed, utilizing corner perturbation and cross-slots to achieve left-hand circular polarization, while the 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.

    Results

    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.

    Conclusions

    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.

  • High Power Microwave Technology
  • Zhaokun Ma , Yunfei Sun , Qiang Zhang , Juntao He , Chengwei Yuan , Zhenqiang Cao
    doi: 10.11884/HPLPB202638.250237
    Background

    With the advancement of high-power microwave (HPM) technology, there is a growing demand for HPM antennas with beam scanning capabilities.

    Purpose

    This paper focuses on beam-scanning technology in the 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).

    Methods

    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.

    Results

    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%. The PHC of the beam scanning antenna exceeds 1 GW.

    Conclusions

    The antenna proposed in this paper exhibits excellent beam scanning performance and high PHC, demonstrating great potential for applications in the HPM field.

  • High Power Microwave Technology
  • Lurong Lei , Dong Wang , Hu He , Sha Xu , Fen Qin , Zhenbang Liu
    doi: 10.11884/HPLPB202638.250331
    Background

    With the development of pulse power technology and plasma physics, high-power microwave technology has developed rapidly, giving rise to various types of high-power microwave sources. Among them, the relativistic magnetron stands out as one of the most promising high-power microwave sources due to its high power conversion efficiency, compact structure, and tunable frequency. At present, the investigations of the relativistic magnetron mainly focus on microwave generation mechanisms, operation characteristics and radiation characteristics at relatively low frequency bands, such as L-band and S-band. The operating characteristics of the relativistic magnetron at higher frequencies are scarcely studied.

    Purpose

    A Ku-band coaxial relativistic magnetron (RM) is designed in this paper to broaden working frequency range of this type of high-power microwave (HPM) source, further expanding its application scope.

    Methods

    A coaxial magnetron structure with 18 inner cavities is applied in this tube. A particle-in-cell (PIC) simulation has been carried out with the coaxial-axial output.

    Results

    The high power microwave with power of 108 MW was detected at 14.613 GHz with a power conversion efficiency of about 43% when the applied voltage was 180 kV, the current was 1.4 kA, the inducing magnetic field was about 0.4 T, and the mode of output microwave in coaxial waveguide is TE01 mode.

    Conclusions

    The simulation results show that the presented tube has a relative high conversion efficiency with low guiding magnetic field and more compact structure, which is convenient for decreasing the volume and weight of the system.

  • High Power Microwave Technology
  • Xiaolong Yan , Yu Wang , Chilu Yan , Jiangqiao Ding
    doi: 10.11884/HPLPB202638.250414
    Background

    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.

    Purpose

    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.

    Methods

    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.

    Results

    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.

    Conclusions

    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.

  • Particle Beams and Accelerator Technology
  • Jimin Wu , Peng Huang , Junyi Wei , Fengping Guan , Bin Ji , Tingfeng Zhang , Jiayi Zhang , Hao Sun , Yaqing Wang , Xianping Li
    doi: 10.11884/HPLPB202638.250282
    Background

    The China Institute of Atomic Energy has designed of a 9.5 MeV ultra-compact cyclotron to support the independence 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.

    Purpose

    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.

    Methods

    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 was constructed to ensure accurate and stable amplitude regulation.

    Results

    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).

    Conclusion

    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.

  • Special Column of 5th Symposium on Frontier of HPLPB
  • Weiling Huang , Renjun Yang , Fang Li , Renhong Liu , Zhijun Lu , Ruiyang Qiu , Tao Yang , Shimin Jiang , Weiwen Chen , Lei Zeng , Rui Yang , Na Ma , Yigang Wang , Zhihong Xu , Xiao Li
    doi: 10.11884/HPLPB202638.250340
    Background

    The C-band photocathode radio frequency (RF) electron gun, with an ultra-high accelerating gradient exceeding 150 MV/m, is a key technology for generating high-brightness electron beams in fourth-generation light sources. However, its output beam features picosecond-scale ultrashort pulses, a wide charge dynamic range of 50 pC to 2500 pC, and an ultra-low transverse emittance of 0.18 mm·mrad@100 pC. Existing measurement methods developed for L/S-band systems can hardly meet the stringent requirements on measurement accuracy and bandwidth for such beams.

    Purpose

    This study aims to develop a high-precision beam measurement system adapted to the characteristics of the C-band electron gun, based on the test platform of the South Advanced Light Source (SAPS).

    Methods

    Firstly, a flange-mounted active integrating charge transformer (Active-ICT) was independently developed to address the challenge of narrow-pulse charge measurement, and a cross-calibration method based on a set of commercial high-sensitivity ICT and terminator was proposed, achieving a measurement linearity better than ±1% full scale (FS). Secondly, to mitigate the significant influence of space charge force in ultra-low emittance measurement, the slit parameters and drift length of the double-slit emittance meter were optimized via Astra simulation, confining the systematic error within 10% in the emittance range of 0.15-0.25 mm·mrad. Thirdly, an optical path combining double-slit collimation and a sector dipole magnet was designed to suppress noise floor interference in energy spread measurement.

    Results

    Preliminary beam experiments were conducted with the established system. The results show that the measured photocurrent and dark current are in good agreement with Faraday cup measurements, and the beam energy curves obtained under different accelerating gradients are highly consistent with beam dynamics simulation results, verifying the reliability and measurement accuracy of the system.

    Conclusions

    This work solves the key beam diagnostics technical bottlenecks in the commissioning of domestic C-band photocathode RF electron guns, and provides core technical support for the engineering development of similar high-gradient injectors.

  • Pulsed Power Technology
  • Zhi Wang , Jincan Wang , Tianyi Li , Chao Xiong , Huibo Tang , Longyu Kuang , Guangyue Hu
    doi: 10.11884/HPLPB202638.250079
    Background

    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.

    Purpose

    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.

    Methods

    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.

    Results

    At 40 kV charging voltage, a discharge current with a peak intensity of 105 kA, a rise time of 1.2 μs, and a flat top width of 1.4 μs is produced, which generates an intense magnetic field of 22 T in the center of a three-turn magnetic field coil of 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.

    Conclusions

    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.

  • Pulsed Power Technology
  • Shifei Liu , Jiande Zhang , Zicheng Zhang , Xudong Qiu , Mingzhu Gao , Rui Li , Yekai Zhou
    doi: 10.11884/HPLPB202638.250264
    Background

    The quasi-square wave output characteristic of a 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 increasingly significant, which has a significant effect on the pulse modulation characteristics of the PFN and further affects the quasi-square wave output characteristics of the generator.

    Purpose

    It is necessary to investigate 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.

    Methods

    This paper presents an electromagnetic coupling analysis of the PFN during the discharging process of PFN Marx generator. Firstly, the electromagnetic coupling phenomena 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.

    Results

    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.

    Conclusions

    Based on the above results, the understanding of electromagnetic coupling in the wave transmission of PFN-Marx generator can be improved, 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 the PFN-Marx generator.

  • Pulsed Power Technology
  • Lijin Gan , Qi Zhou
    doi: 10.11884/HPLPB202638.250322
    Background

    Series resonant capacitor charging power supply is widely used in the field of pulse power due to its high efficiency, high power density, and short-circuit resistance. However, its traditional PFM constant current charging control method leads to significant charging losses and reduced efficiency, which is particularly prominent in the early stages of charging.

    Purpose

    A multimodal hybrid constant-current charging control strategy is proposed to enhance both the charging efficiency and input power utilization.

    Methods

    This strategy achieves smooth transitions of charging voltage while reducing charging losses and improving efficiency through collaborative control of half-bridge mode (early charging stage), hybrid mode (mid charging stage), and full-bridge mode (late charging stage). In addition, the conversion of working modes is achieved by multiplexing power devices, which not only meets the requirements of high-voltage charging but also reduces system costs.

    Results

    Based on this approach, a 650 V/1 A charging power supply prototype has been designed and built. Experimental results demonstrate that, compared to conventional PFM control, the proposed strategy significantly improves overall charging efficiency, achieving a maximum efficiency of 96.4%.

    Conclusions

    This method not only provides an effective solution for capacitor energy storage charging systems with high efficiency and low cost, but its modal switching mechanism is also transferable to the design of other resonant converters, demonstrating broad engineering applicability.

  • Pulsed Power Technology
  • Tianwei Shi , Xiaoming Yue , Song Jiang , Zi Li , Yonggang Wang
    doi: 10.11884/HPLPB202638.250399
    Background

    High-power pulsed applications increasingly require power supplies capable of high-current bipolar output and flexible controllability. However, achieving high power density while maintaining pulse precision and current-sharing stability remains a significant challenge pulsed source design.

    Purpose

    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.

    Methods

    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 good scalability.

    Results

    Experimental results demonstrate that, under DC bus voltages ranging 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$ \mathrm{\; ns} $ pulse width, the four-device paralleled branch achieves a current-sharing imbalance factor of 12.87%, validating the effectiveness of the cooperative gate-drive scheme and the use of independent gate resistors.

    Conclusions

    These findings indicate that the proposed compact integrated design successfully balances high-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.

  • Special Column of 5th Symposium on Frontier of HPLPB
  • Zhipei Hou , Bihe Deng , Chengyuan Chen , Chunhua Liu , Qilin Zhang , Shaobo Gong , Lin Nie , Zhongbing Shi
    doi: 10.11884/HPLPB202638.250317
    Background

    The study of multi-scale turbulence and related anomalous transport under high-performance plasma operation remains an important topic in the research of magnetic confinement fusion. The parameter range of plasmas in the tokamak experiment determines that far-infrared laser collective scattering is the optimal diagnostic method for multi-scale turbulence diagnostics.

    Purpose

    This paper discusses the overall design parameters of the diagnostic system and provide a detailed introduction to the design of the windows for the multi-scale turbulence collective scattering (MSTCS) diagnostic system on the HL-3 Tokamak.

    Methods

    The laser beam entrance window of the MSTCS diagnostic system is located in the mid-plane port #6 of the HL-3 tokamak, and the scattered light beams exit from the windows in the mid-plane port #12. The design aspects of the windows include the material selection, clear aperture calculation, window thickness design, mechanical design, and surface quality requirements. Several interrelated factors need to be considered in the design process. These include the diagnostic wavenumber range, wavenumber resolution, wavenumber purity of the scattering data, laser beam transmission coefficients, and the requirements for vacuum sealing and safety.

    Results

    On the basis of these considerations, a corresponding design scheme was formulated. The technical details of the analysis and design process as well as the design results are presented.

    Conclusions

    The MSTCS diagnostic system has been successfully installed on HL-3, and preliminary experimental data confirm the vacuum safety and optical performance of the diagnostic windows, thereby validating the overall design.

  • Advanced Interdisciplinary Science
  • Shuai Zhao , Yi Wu , Guoying Feng
    doi: 10.11884/HPLPB202638.250467
    Background

    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.

    Purpose

    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.

    Methods

    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.

    Results

    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.

    Conclusions

    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.

  • Advanced Interdisciplinary Science
  • Tianzi Bai , Ying Huai , Tingting Liu , Shuqin Jia , Liping Duo
    doi: 10.11884/HPLPB202638.250298
    Background

    The reaction kinetics in lasers often involves a lot 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).

    Purpose

    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.

    Methods

    To address the aforementioned challenges, this study introduced 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 was 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.

    Results

    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.

    Conclusions

    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.

  • Special Column of 5th Symposium on Frontier of HPLPB
  • Xu He , Yuncan Ma , Weiwei Guo , Jianye Song , Zuge Yang , Kun Wang , Jun Li , Limin Meng
    doi: 10.11884/HPLPB202638.250323

    Titanium and its alloys are the predominant base materials for oral implants. However, challenges such as prolonged osseointegration periods and limited success rates persist due to their inherent low surface bioactivity. Femtosecond laser processing has emerged as an innovative, non-thermal, and high-precision surface modification technique, offering a novel approach to precisely tailor the micro-nano topography, chemical composition, and biological performance of implant surfaces. This review summarizes research advances in femtosecond laser surface treatment of titanium implants over the past five years. It systematically elaborates on methods for constructing specific surface architectures by regulating parameters such as laser power, wavelength, scanning strategies, and pulse patterns. Furthermore, it introduces hybrid processing strategies that combine femtosecond laser with techniques like hydroxyapatite deposition, sandblasting, and 3D printing, highlighting their synergistic effects. By comparing femtosecond laser processing with conventional surface treatment technologies (e.g., sandblasting and acid etching, electrochemical deposition, plasma sputtering), this paper analyzes its unique advantages in terms of processing precision, heat-affected zone, biocompatibility, and long-term stability. Finally, current challenges (e.g., equipment cost, processing efficiency) are summarized, and future development directions are proposed, including personalized implant manufacturing, multifunctional surface construction, and integration with other advanced technologies.