The quasi-optical (QO) pulse compressor based on a linear cavity represents a promising approach for generating nanosecond terahertz (THz) pulses with amplified power and tunable pulsewidth. However, its performance is significantly limited by the coupling loss, which reduces the gain factor. To overcome this limitation, we propose a novel double-path linear cavity for the pulse compressor, which can eliminate the coupling loss and enhance the gain factor. In this configuration, one QO path is used to store the THz energy and generate tunable THz pulses, while the other path is utilized to compensate for the THz coupling loss through destructive interference. A double-wafer laser-driven semiconductor switch (LDSS) with controllable reflectance functions as both the input and output coupler, enabling optimization of the intracavity field distribution for maximum gain. Through simulations and experiments, we investigate the coupling-loss compensation mechanism and the operational conditions of the double-path cavity, demonstrating significant improvement in performance. Experimental results across 230-260GHz show that nearly zero coupling loss is maintained while tuning the pulsewidth from 3 to 15ns. The gain factor reaches up to similar to 37 under optimal conditions and remains consistently more than double that of a conventional single-path linear cavity. Compared with the results reported in previous literature, the proposed pulse compressor achieves the state-of-the-art performance in both gain factor and pulsewidth tunability.

Pulsed magnetic field nuclear magnetic resonance (PMF-NMR) has emerged as a rapidly evolving research frontier in high-field science. To address stringent spatial homogeneity requirements, this work proposes a passive shimming approach employing semi-circular shim rings with radial slits. This design simultaneously enhances magnetic field homogeneity and suppresses eddy current effects, while maintaining excellent mechanical stability. Simulation results show that the proposed structure significantly improves magnetic-field homogeneity within a 1 cm diameter spherical volume (DSV) region at the magnet center—from 2764 ppm to 321 ppm. For experimental validation, a differential magnetic field measurement system was developed using a dual-layer planar printed circuit board (DLP-PCB) coils, enabling real-time assessment of axial field homogeneity in the pulsed magnet’s central region. Tests conducted on a 3.5 T pulsed magnet platform confirm nearly an order-of-magnitude improvement in axial field homogeneity after shimming, showing close agreement with the simulated axial profile. This study includes an analysis of measurement uncertainties and limitations to ensure the reliability of the results and to guide future PMF-NMR system development.

The unexpectedly small ordered moments of CeNiAsO, a candidate for correlated p-wave magnet, have posed a serious challenge to the precise determination of its magnetic structure, hindering the understanding of its fundamental properties. By leveraging the high sensitivity to local internal fields, our ^75As nuclear quadrupole / magnetic resonance experiments reveal a commensurate antiferromagnetic order with a small out-of-plane moment m_z≈0.05 μ_B. This tilted magnetic configuration not only rotates the spin polarization axis away from the crystallographic 𝐜-axis, but also enhances the non-relativistic spin splitting. We refer to this rare paradigm as a tilted p-wave magnet.

The high voltage power supply system for the pulsed high magnetic field facility at the Wuhan National High Magnetic Field Center (WHMFC) will be upgraded to a 167 MJ capacitor bank system comprising 73 modules. This system will serve 27 magnet experimental stations over the next five years. The capacitor bank system is located on the second floor of the Pulsed Building, while all experimental stations occupy the first floor; each floor covers approximately 2000 square meters. The 27 experimental stations are divided into four independent zones. Each zone is supplied by dedicated capacitor bank modules and features an independent grounding system. This configuration ensures that operators in unaffected zones are not exposed to hazards during high voltage or high magnetic field experiments conducted in another zone, requiring evacuation only from stations within the active zone. Consequently, this design significantly improves experimental efficiency and greatly enhances overall facility utilization.

Pulsed field magnetometers are simple and inexpensive, and are capable of achieving high magnetization fields, making them suitable for the measurement needs of ultra-high coercivity permanent magnets. However, the eddy currents generated in the pulsed discharge test can lead to deviations in the test results. In this paper, a calculation method applicable to eddy current correction in pulsed-field magnetometers is proposed. According to the principle that the eddy current is proportional to the rate of change of the magnetic field, the same size and different frequency pulses are used to excite the permanent magnet, thus quantifying the size of the eddy current magnetic field, and the influence of eddy current on the hysteresis loop measurement results of the permanent magnet can be effectively deducted.

The critical current (Ic) of high-temperature superconducting (HTS) tapes is typically measured under steady-state magnetic fields using DC power supply. However, such fields are generally limited below 35 T, and generating higher steady-state magnetic fields requires considerable time and resources. In contrast, pulsed-field magnets enable shorter testing time and can exceed 50 T. Thus, we developed a high-frequency pulsed current injection platform for measuring Ic of HTS tapes under pulsed magnetic fields. Additionally, etched micro-bridges were employed to proportionally reduce the applied current and mitigate thermal effects that could degrade measurement accuracy. Taking the 50 T, 100-ms flat-top pulsed magnetic fields at the Wuhan National High Magnetic Field Center (WHMFC) as a potential application scenario, the proposed platform integrates a 20 kHz / 6.5-digit multimeter and a mixed-signal oscilloscope for synchronized acquisition. We investigated the effects of injection frequencies (2 kHz to 100 Hz), magnetic fields (0 T to 2 T), and temperatures (65 K to 83 K) on platform performance. The proposed platform was further validated against the conventional DC measurement method at 77 K, self-field.

Pulsed magnets producing 45-100 T magnetic fields with millisecond pulse durations are essential tools for advanced research in condensed matter physics and materials science. Conventional radially nested multi-coil systems, however, suffer from high inductance, strong electromagnetic coupling, and excessive energy consumption, which limit the achievable magnetic field. To overcome these limitations, a novel axially stacked pulsed magnet configuration is proposed. Investigating its electromagnetic and thermal responses requires an efficient multi-physics computational framework. Existing rapid-computation tools, such as PMDS, which assume coaxial and parallel coils, are unsuitable for this topology, while commercial finite-element software often involves long computation times and convergence issues. To address these challenges, a dedicated numerical framework is developed, integrating circuit equations, magnetic-field diffusion, and heat conduction, while accounting for magnetoresistance and eddy-current effects. A MATLAB-based code is validated against COMSOL simulations, demonstrating deviations below 2%. In a 95 T case study, the axially stacked design reduces self and mutual inductances by over 60%, decreases energy demand by 60%, and shortens pulse width by 36%. The proposed axially stacked topology offers a new pathway toward realizing ultra-high-field pulsed magnets exceeding 100 T.

High-voltage power supplies (HVPSs) are widely used in medical, industrial, and scientific equipment, where output ripple performance and dynamic response are critical to overall system functionality. However, due to the limitations of passive components and feedback control, achieving both low ripple performance and fast dynamic response remains challenging. This article proposes a model-based open-loop ripple compensation scheme for LCC resonant converters with fast response, which is applied to n multiphase interleaved LCC resonant converters via a compensation network composed of a reversely series-connected LCC converter. The compensation network enables active ripple cancellation of the output voltage. Through precise circuit modeling, the control strategy of the compensation network required under varying output conditions is precalculated offline, thus eliminating feedback control constraints on response speed. A 10 kV, 40 mA prototype is constructed to validate the proposed compensation scheme. Experimental results confirm that the compensation scheme proposed significantly improves ripple performance without compromising dynamic response capability.

Nanosecond multipulse terahertz (THz) sequence with tunable relative phase is essential for spectroscopy applications, but its generation remains challenging. To realize such a pulse sequence, we propose an optical-path-based phase shifting method and a phase-correction superheterodyne detection scheme for a quasi-optical (QO) pulse compressors system in this article. The system incorporates two QO pulse compressors to generate two phase-coherent THz pulses with amplified power. A phase-shifting mirror embedded in the optical path of one compressor enables the QO distance adjustment, allowing the relative phase shifting between the two pulses. Using hardware-based mixing and software-based IQ demodulation, accompanied by phase correction, the relative phase is accurately measured to ensure precise phase tuning. Experimental results demonstrate that the relative phase can be precisely tuned over two full cycles while maintaining a gain factor of similar to 8 for each pulse. By integrating phase-tunable nanosecond pulse sequence generation with power amplification, this work offers a highly promising solution for advanced spectroscopy applications.

Magnetic field prediction is a core aspect of magnet design, yet traditional finite element methods (FEM) face computational bottlenecks when handling complex structures. This paper proposes a DeepONet-based surrogate modeling approach for magnetic field prediction, designed to efficiently map coil structural parameters to spatial magnetic field distributions. The model employs a dual-branch input network that separately encodes coil geometric features and spatial coordinate information, subsequently outputting each magnetic field component. Through validation on representative coil cases featuring symmetric and asymmetric cross-sections, the model demonstrates prediction accuracy comparable to FEM while achieving significantly accelerated computational efficiency. Results indicate that the proposed method exhibits strong structural adaptability and generalization capabilities, providing an efficient solution for optimized magnet design.

Underwater electrical wire explosion (UEWE) in planar arrays enables strong, spatially controllable shock waves (SWs). This work experimentally investigates the UEWE of a single copper wire and planar multiwire arrays with nearly identical total mass under an initial stored energy of 1.6 kJ. Discharge current and voltage waveforms are used to determine energy deposition before and after vaporization, while a pressure sensor measures the SW peak pressure, pulsewidth, impulse, and energy density at a fixed stand-off distance. Splitting a single wire into multiple parallel wires only slightly alters electrical matching but significantly increases energy deposition and strengthens the resulting SWs. Relative to a single wire, a nine-wire array enhances the SW peak pressure and energy density by about 124% and 272%, respectively, while nearly halving the pulsewidth. For both single- and split-wire configurations, the SW amplitude first rises and then falls with total wire mass, and a smaller mass produces steeper fronts and shorter pulses. Inter-wire spacing has little effect on deposited electrical energy but strongly influences SW convergence, yielding an optimal spacing that maximizes amplitude. A 3-D simulation model, extended from a single-wire configuration to planar arrays, reproduces the measured enhancement and shows that primary superposition in the gaps and secondary convergence of reflected compression waves dominate far-field amplification and wavefront uniformity. The combined results provide design guidelines for UEWE-based planar arrays, indicating that increasing wire multiplicity and choosing a spacing of roughly one quarter of the wire length effectively enhances SW amplitude and uniformity.

Metallic thin-walled sheets are widely used in fields of biology, medicine, and energy. However, the residual stress generated during forming and processing severely affect their fatigue strength and structural stability. This paper proposes a method to control residual stress using pulsed strong magnetic fields: placing the workpiece in a pulsed magnetic field and injecting high-frequency oscillating current through it. The oscillating electromagnetic force (OEF) acts on the surface of the sheet, causing plastic deformation and releasing the residual stress in the elastic zone. The oscillating current stimulates dislocation migration and rearrangement, which helps to release the residual stress within grains. Experiments show that under the action of 22 kHz oscillation, the residual stress on the side wall and bottom of the sheet is reduced by 43

Conduction-cooled no-insulation (NI) ReBCO magnets are attractive for compact high-field systems because they combine cryogen-free operation with intrinsic quench protection. Their field temporal stability, however, is limited by the coupled effects of screening-current-induced field (SCIF) relaxation and charging delay caused by turn-to-turn current sharing. This paper investigates a 50 K, 2 T desktop ReBCO magnet composed of 13 double-pancake (DP) coils and proposes an overshooting-current-profile optimization method for suppressing post-excitation field drift. A 2-D axisymmetric homogenized model, based on the T-A formulation and a radial voltage-control equation, is developed to calculate both screening-current evolution and NI current redistribution. A surrogate-model-based optimization procedure, combining Latin hypercube sampling and Gaussian process regression, is then used to analyze the effects of overshoot ratio, overshoot ramp rate, and plateau duration. The results show that the overshoot ratio is the dominant parameter controlling the sign and magnitude of the center-field drift, whereas a sufficiently long plateau can significantly reduce the overshoot required for low-drift operation. The optimized charging profile reduces the center-field drift rate to below 50 ppm/h in the 3000–5000 s post-excitation window. The study provides a practical charging strategy for improving the field temporal stability of conduction-cooled NI ReBCO magnets.

The second phase construction of the Wuhan High Magnetic Field Center (WHMFC) is currently underway, aiming to comprehensively upgrade the systems developed during the first phase. The capacitor bank capacity will be increased from 28 MJ to 167 MJ, supporting the development of new pulsed magnets, including a 110 T magnet with a 10 mm bore and a 70 T flat-top magnet sustaining 10 ms within a 14 mm bore. A flat-top pulsed magnet was designed and fabricated based on the principle of sequential discharge of multiple capacitor banks, achieving a peak magnetic field of 71.36 T, a duration of 12.11 ms, and a flatness of 0.39%. An axially stacked high-field pulsed magnet configuration is proposed, which effectively mitigates strong electromagnetic coupling. Additionally, a novel pancaketype magnet structure with radial reinforcement has been proposed. Compared to traditional hoop-strengthened designs, this structure offers significantly improved reinforcement efficiency.

The efficient operation of a gyrotron relies on a specific magnetic field distribution and a stable magnetic field. To this end, a dual-coil pulsed magnet is proposed. By inversely solving for coil current densities based on a reference magnetic field distribution and incorporating an asymmetric structural design, the two coils of the magnet can generate an identical magnetic field distribution within the target region while remaining mutually decoupled. This design facilitates the application of the flat-top pulsed magnetic field (FTPMF) in gyrotrons and is expected to enhance both field strength and stability. The proposed scheme can be readily extended to most pulsed magnets used in gyrotrons.

This study realizes a novel standoff-free vaporizing foil actuator welding (VFAW) technique for titanium-steel joining under low welding energy by introducing an interlayer. Notably, standoff-free titanium-steel welding cannot be achieved even at a high welding energy of 16.2 kJ without an interlayer, while reliable standoff-free welding was successfully realized by employing either Al-1100 or T2-Cu as the interlayer. The welding window was significantly regulated by interlayer material and thickness: the highest critical welding voltage (12 kV) was obtained for the 0.1 mm Al-1100 interlayer, whereas the lowest critical voltage (8 kV, corresponding to a minimum welding energy of 3.2 kJ) was achieved for the 0.3 mm T2-Cu interlayer. Peel tests confirmed that the 0.3 mm T2-Cu interlayer delivered the optimal mechanical performance, with a peak peel strength of 1417 N at 18 kV (the highest among all test groups). To clarify the underlying mechanism, microstructural characterization and finite element method (FEM) simulations were conducted. Scanning electron microscopy (SEM) observations showed the weld interface exhibited irregular/wavy morphologies, with diffusion layers whose formation was tailored by welding energy, interlayer material and thickness. Electron backscatter diffraction (EBSD) results confirmed grain refinement, dynamic recrystallization and recovery at the interface, which contributed to enhanced joint integrity. FEM simulations further demonstrated that the relative motion of the plates induced a spatiotemporally evolving temporary gap, which served as a critical prerequisite for successful metallurgical bonding. The proposed technique enables high-strength titanium-steel joining with low energy consumption, holding substantial application potential in engineering fields demanding lightweight composite structures.

Advances in high-stability flat-top pulsed magnets and programmable power supplies have enabled the precisely controllable radiation of gyrotrons exceeding the 1-THz band. However, high-efficiency operation under the “hard-excitation” condition and mode shadowing is still difficult for terahertz gyrotrons. In this article, a novel temporal profile of the pulsed field is introduced to achieve efficiency enhancement and operating-domain extension. An overshoot at the pulse front realizes smooth conversion between the soft and hard excitation regions within the pulsewidth scale. As an advanced demonstration, a 1-THz gyrotron equipped with a 40-T flat-top magnet is developed and investigated. Steady oscillation with power above 8 kW at 1.001 THz is predicted in this drastic time-varying system. The efficiency is more than doubled compared to the value that can be directly excited. The feasibility of this waveform based on the model predictive control (MPC) is also discussed. This scheme is generalized as it imposes no specific requirements on the gyrotron itself. This work will promote the research on the high-power terahertz sources and their applications such as high-resolution spectrometers.

A newly designed electromagnetic forming actuator has been proposed to enable curved-geometry sheet metal forming, cannot be efficiently realized by conventional electromagnetic forming. In the pursuit of fast designing the actuator, an analytical model was derived to obtain the relationship between the produced magnetic pressure and the system geometric parameters of the actuator. Based on this analytical formulation, we explored the regulatory behavior and impact mechanism of various parameters of the actuator on the magnetic field, magnetic pressure, and efficiency of the forming system, which has been validated by the results from finite element simulations. A design criterion is proposed for optimization of the actuator. And accordingly, a series of experiments have been performed to validate the feasibility of the proposed actuator for electromagnetic calibration.

Electromagnetic wiping offers the advantages of non-contact operation and ease of control compared to the gas wiping. However, the single-phase electromagnetic wiping technique predominantly generates an axially oriented magnetic flux, resulting in limited axial electromagnetic force and reduced wiping efficiency. This paper introduces a three-phase electromagnetic wiping (TPEW) method for hot-dip galvanizing pipes. Compared to single-phase coils, the three-phase coils in the TPEW create a traveling magnetic field along the pipe axis, generating stronger axial electromagnetic forces on the surface of the galvanized coating, thereby achieving more effective removal of excess liquid zinc. Furthermore, the frequency and amplitude of the TPEW coil currents can be easily adjusted, enabling precise modulation of the traveling magnetic field and the electromagnetic forces acting on the liquid zinc. This ultimately allows for accurate control over the thickness and uniformity of the coating. Experimental results show that at a current amplitude of 70 A and a frequency of 50 Hz or lower, the TPEW technique effectively reduces the average coating thickness to below 40 mu m. The modeling, simulation, and experimental results of the prototype demonstrate the feasibility of the TPEW approach, which effectively reduces the coating thickness and enhances its uniformity.

Pulsed field magnetometer (PFM) can achieve higher magnetic field at a lower cost, suitable for measuring ultrahigh coercive permanent magnets, but it generates eddy currents during the test, which affects the measurement accuracy. To solve this issue, this article proposes a new method for hysteresis loop measurement of permanent magnetic materials that requires only four half-wave pulses, called the negative-positive-positive (NPP) sequential method. According to the NPP method, we employ the difference between magnetic flip and no-flip pulses to eliminate interference signals like eddy currents while retaining the magnetic signal of the permanent magnet. In addition, this study addresses two major issues of the NPP method in magnetic measurement applications: extracting information about the eddy current magnetic field generated by the background magnetic field and by the magnetic polarization field of the sample, respectively, from the measured signals. Experimental results proves that this measurement method can achieve a measurement accuracy within 1% deviation and a test repeatability within 0.25% deviation.