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 to address the challenge of precise target alignment under vacuum conditions and enhance 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.

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.

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 good scalability.

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.

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.

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.

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.

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.

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, 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.

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).

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 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.

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.

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.

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.

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 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.

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.

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.

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.

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 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.

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.

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.

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 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.

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.