Email alert
RSS
Recommend Articles
Display Method:
2026,
38: 041001.
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.
2026,
38: 041002.
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.
2026,
38: 041003.
doi: 10.11884/HPLPB202638.250270
Abstract:
Background Purpose Methods Results Conclusions
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.
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.
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.
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 10−12 Pa·L/s.
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.
2026,
38: 041004.
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.
2026,
38: 041005.
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.
2026,
38: 042001.
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.
2026,
38: 042002.
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.
2026,
38: 043001.
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 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.
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.
2026,
38: 043002.
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.
2026,
38: 043003.
doi: 10.11884/HPLPB202638.250331
Abstract:
Background Purpose Methods Results Conclusions
With the development of pulse power technology and plasma physics, high-power microwave technology has rapidly developed, 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 mechanism, operation and radiation characteristics at the relative low frequency band, such as L-band and S-band. The operating characteristics of relativistic magnetron at higher frequencies are scarcely studied.
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.
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.
The high power microwave with power of 108MW was detected at 14.613 GHz with 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.
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 to decrease the volume and weight of the system.
2026,
38: 043004.
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.
2026,
38: 044001.
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 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.
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 was 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.
2026,
38: 045001.
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.
2026,
38: 045002.
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.
2026,
38: 045003.
doi: 10.11884/HPLPB202638.250322
Abstract:
Background Purpose Methods Results Conclusions
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.
A multimodal hybrid constant-current charging control strategy is proposed to enhance both the charging efficiency and input power utilization.
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.
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%.
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.
2026,
38: 045004.
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}$ \mathrm{\; 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.
2026,
38: 049001.
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.
2026,
38: 049002.
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.
2026,
38: 044002.
doi: 10.11884/HPLPB202638.250340
Abstract:
Background Purpose Methods Results Conclusions
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.
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).
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.
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.
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.
Design of windows for multi-scale turbulence collective scattering diagnostic system on HL-3 Tokamak
2026,
38: 046001.
doi: 10.11884/HPLPB202638.250317
Abstract:
Background Purpose Methods Results Conclusions
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.
This paper will discuss 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.
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 inter-related 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.
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 will be presented.
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.
2026,
38: 049003.
doi: 10.11884/HPLPB202638.250323
Abstract:
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.
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.
