Vacancy-engineered trivalent rare earth ions (Sm, Dy, and Lu) doped BNBST ceramics for pulse power energy storage

Polymer-based film capacitors are crucial components for modern electronic devices and advanced pulse power systems, but their performance is fundamentally constrained by the long-standing trade-off between high energy density and high charge-discharge efficiency. Here, a dipole-glass polymer design is introduced, in which the active dipolar side groups are incorporated into a rigid polyimide backbone through flexible spacers. The rigid polyimide backbone provides a wide bandgap and a glassy matrix that suppresses leakage current and enables an ultrahigh breakdown strength of 964 MV m-1, while the active acetyl side groups deliver easy and reversible orientational polarization with minimal steric hindrance. As a result, the optimized DGPI-Ac film achieves a record-high discharged energy density of 15.3 J cm-3 with a charge-discharge efficiency higher than 95% at room temperature, and it also shows excellent high-temperature capacitive performance up to 200°C. This work establishes rational side-chain engineering as an effective strategy, thereby unlocking the inherent energy storage potential of polymer dielectrics and advancing high-power electrostatic energy storage technologies.

Polymer-based dielectrics are widely employed in electrostatic energy storage capacitors serving as pulse power supply owing to their lightweight nature and rapid charge-discharge capability. However, their intrinsically low dielectric constant severely limits energy storage density. Although high-dielectric-constant nanofillers are commonly incorporated to enhance permittivity, organic-inorganic interfacial incompatibility often induces particle agglomeration and structural defects. In this work, we propose a confined co-doping strategy for structured polymer dielectrics, wherein BaTiO3 and Al2O3 nanoparticles are co-doed within the ferroelectric core P(VDF-HFP) of coaxial fibers and undergo self-assembly. This approach simultaneously enhances both energy density and charge-discharge efficiency. As a result, the 1 wt% BaTiO3/1 wt% Al2O3 core co-doping composite dielectric achieves a discharged energy density of 19.2 J/cm3 and a charge-discharge efficiency of 81.0%, and maintains stable performance over 1 × 105 cycles under an electric field of 400 kV/mm. This confined co-doping strategy thus provides an effective and scalable route for developing polymer-based dielectrics with high energy density and high reliability.

The effectiveness of non-thermal plasma (NTP) in improving the bond strength of different resin cements to different glass ceramics under various surface treatment protocols remains unclear. Moreover, the influence of specific plasma devices and the material-dependent response of ceramic-resin cement systems to NTP have not been sufficiently investigated. The purpose of this in vitro study was to evaluate the effect of NTP on the shear bond strength of different resin cements to different glass ceramics by comparatively assessing multiple surface treatment protocols. A total of 240 specimens of each glass ceramic group (IPS e.max CAD (E), Vitamark II (V)) were divided into 24 groups according to the combination of 6 surface treatments ((control), hydrofluoric acid (HF)+ceramic primer (Pr), Pr, HF+plasma (Pl) + Pr, Pl + Pr, and Pl) and two different resin cements (Single Bond+RelyX Ultimate (R) and ZenitCem (Z)). NTP was applied with an AC microsecond pulse power supply (5kHz, 20kV, 90s). Specimens were cemented to composite cylinders. After storage in an oven, SBS was measured. The results were analyzed using three-way ANOVA, post-hoc tests, and targeted pairwise comparisons, with the significance level set at α = 0.05. The effectiveness of NTP is material- and cement-dependent and should be considered as a selective surface modification strategy rather than a universal alternative to conventional surface treatments. The V-Pl-Z group showed significantly higher SBS values than the V-Z group, and these values were within the clinically acceptable range (p < 0.05). In the V groups treated with HF + Pr and HF + Pl+Pr, R demonstrated higher bond strength values than Z. HF surface treatment increased the SBS values for all groups (p < 0.05). The effectiveness of NTP is material- and cement-dependent and should be considered as a selective surface modification strategy rather than a universal alternative to conventional surface treatments CLINICAL SIGNIFICANCE: This study demonstrates that atmospheric non-thermal plasma does not universally enhance ceramic-resin cement bonding. Its effectiveness depends on the ceramic substrate, resin cement type, and surface treatment protocol. Clinicians should therefore apply plasma selectively.

Lithium-ion batteries (LIBs) are subject to mechanical abuse both in electric vehicles and consumer electronic applications when dropped, which can lead to capacity degradation even if the cells survive the impact. This study investigates the impact of mechanical damage on the electrochemical performance of LIBs, focusing on capacity retention and internal resistance changes. The batteries were subjected to dynamic mechanical impact using varying impact energies (3J, 5J, and 7J) while measuring internal resistance and capacity before and after the impact. Hybrid Pulse Power Characterization (HPPC) was employed to assess internal resistance and capacity degradation across multiple cycles. Our results demonstrate that even minor mechanical damage can cause significant performance decay, especially after several cycles. The study also reveals that the state of charge (SOC) prior to impact has a minimal effect on the survival rate of the cells but influences the extent of damage observed. Post-impact analysis using optical microscopy indicates structural damage, including separator tears and delamination, contributing to capacity fade. This work highlights the importance of considering intermediate mechanical damage in LIB safety and performance assessments.

ABSTRACT This work presents a systematic study on the integration of highly nonlinear fiber (HNLF) into an actively mode-locked nanosecond erbium-doped fiber laser (EDFL) cavity, while assessing the performance and stability of high order harmonics (up to the 105th order) via comparative analysis of setups with a standard single-mode fiber and their respective HNLF-integrated setups, specifically characterizing the impact of nonlinearity on peak power, full-width-at-half-maximum (FWHM), and pulse stability. The results indicate that adding HNLF enhances peak power, particularly at lower harmonic frequencies, while improving the FWHM values. Peak power and FWHM were found to be dependent on both the modulator driving signal’s frequency and its peak-to-peak voltage. In the non-HNLF setup, the peak power varied from 3.8 dBm to −6.19 dBm, and the FWHM ranged from 12.5 ns to 7.5 ns. In contrast, in the HNLF-integrated setup, the peak power ranged from 4.62 dBm to −3.37 dBm, and the FWHM varied from 10.5 ns to 9.5 ns as the modulator driving frequency was adjusted. The configuration with HNLF integration presents additional measurable improvements not only in pulse power and FWHM but also in several measures of spectral quality. The integrated configuration achieved an optical signal-to-noise ratio (OSNR) of 69.89 dB as compared to the length-matched standard SMF-28 configuration’s OSNR of 61.56 dB; and a side mode suppression ratio (SMSR) of 68.7 dB at a modulation frequency of 9.78 MHz, which was 6.6 dB greater than that of the corresponding non-HNLF configuration. Thus, the contribution of HNLF integration not only extends to pulse shaping but also encompasses simultaneous enhancements in optical signal quality and pulse train coherence, both of which are directly applicable to optical communications and sensing applications.

This paper presents a comparative study of four optimization algorithms, namely Gauss-Newton (GN),Levenberg-Marquardt (LM), Trust-Region (TR)and (Broyden-Fletcher-Goldfarb-Shanno (BFGS), for parameter identification of a second-order (2RC) equivalent circuit model of lithium-ion batteries using INR21700-45E cell data over a 10%-100% state-of-charge range. The algorithms are evaluated in terms of fitting accuracy, computational efficiency, and parameter consistency. TR and BFGS achieved lower mean rmse values of 0.922mV and 0.971mV, respectively, with [Formula: see text] values above 0.988 across most SOC levels, while LM produced a mean rmse of 2.441mV. The GN method showed poor convergence and unreliable parameter estimation under the tested conditions. Model validation under Hybrid Pulse Power Characterization and C/2 discharge tests showed that TR and BFGS maintained voltage prediction errors below 0.022V and 0.065V, respectively, whereas LM exhibited larger deviations in dynamic conditions. Computationally, LM was the fastest method (0.244s), followed by BFGS (0.383s) and TR (0.655s). The results indicate that TR and BFGS provide improved estimation accuracy and robustness, while LM offers lower computational cost, providing useful guidance for optimization algorithm selection in battery modeling and battery management system applications.

The efficiency of energy deposition during laser lithotripsy is strongly influenced by the interaction between laser radiation and the water layer between fiber tip and stone. This study investigates the transmission of holmium:YAG (Ho:YAG) and thulium fiber laser (TFL) radiation through vapor channels under varying fiber-to-target distances (0.5-3 mm). Both lasers were set to deliver pulses of 1 J. The fiber was positioned in a water-filled cuvette on top of an integrating sphere to measure transmittance through different water layer thicknesses. A 580 μs, high-power (up to 7 kW) Ho:YAG laser pulse creates a vapor channel that enables continuous transmission of the laser energy to the target surface for standoff distances > 0.5 mm. With the TFL's longer (2 ms), lower peak power (500 W) pulses, repeated cycles of vaporization and bubble collapse occur, resulting in a reduced energy transmission efficiency compared to the Ho:YAG laser pulses.

This work proposes a general framework for the optimal design of radiofrequency pulses in MRI. Based on optimal control theory, it proposes a Python-based numerical implementation using state-of-the-art nonlinear optimization solver (IPOPT). This study proposes three main contributions. It allows the incorporation of hard constraints to the problem and their consistent integration into the optimization process. It proposes to express the pulse as wavelet coefficients which proves to be highly effective in an applicative context. Finally, an innovative approach to minimize the pulse peak amplitude is presented by taking advantage of the efficient constraint management. The proposed framework is made available through a Python package, along with Jupyter Notebooks to reproduce the paper results. It also allows external users to solve their own design problem, benefiting from the generality and flexibility of the proposed implementation. The efficacy of the proposed method is validated in the context of short- selective excitation and -robust problems, with a primary focus on power and energy minimization. The optimized pulses provide a substantial enhancement regarding the compromise between energy/peak power and overall pulse performances, when compared to state-of-the-art solutions.

The long-pulse pulsed power facility composed of capacitor banks can serve as a loading method to provide high-speed, high-pressure implosion conditions for solid liners. The implosion process is characterized by high symmetry, repeatability, and ease of diagnostics, enabling the study of physical properties of materials and complex fluid dynamics under extreme conditions. However, previous designs for the load region were optimized primarily for cylindrical convergence structures, which are less adaptable when dealing with non-converging geometries. Moreover, for experiments that require comparing physical differences caused by geometric configurations, it is generally not straightforward to perform the same round of experiments using the same loading method. Therefore, we develop a new structure of load region in FP-2 (facility for Fluid Physics investigations-the second generation) that allows planar and cylindrical dual-loading modes to be carried out simultaneously. By calculating dynamic model combined with full-circuit model and electromagnetic simulation, the structural parameters of flyer plate and cylindrical liner were designed. Based on the loading device combined with laser interferometry diagnostic technology, verification experiments, such as flatness test of large-sized flyer plate, were conducted. The experimental results of planar launch and cylindrical implosion in the same experiment demonstrate the feasibility of simultaneous loading. In addition, the dual-loading method was finally applied to spalling experiment, rebound velocity signals were obtained for two kinds of geometric configurations. Compared with conventional single-mode systems, the new device enhances the efficiency-to-cost ratio of experiments, lays a foundation for further structural optimization to enable configuration comparison studies under identical loading conditions, and provides a dual-loading platform for other physical experiments, such as interfacial instability investigations.

Solid State Marx Generators (SSMGs) are increasingly used in pulsed power applications requiring high repetition rates. However, when thyristors are employed as primary switches, their inherent turn-on delay limits the output pulse rise time. In this work, a solid state Marx generator is developed in which saturable magnetic cores are integrated in series with thyristor stages as magnetically assisted elements, improving the pulse rise time characteristics. The magnetic cores delay current conduction until saturation, thereby sharpening the rising edge and mitigating the effect of thyristor turn-on delay. The novelty lies in this integration, which enables inherent core reset through the Marx charging and discharging cycle without additional circuitry. A governing equation is developed to describe the interaction between thyristor turn-on dynamics, the magnetic core saturation process, and the circuit current, providing a physical explanation of the observed volt-secproduct driven switching behavior. The system produces negative pulses up to 13kV with a rise time of 224ns and pulse width of 1.1 μs (FWHM) at 25Hz of repetition rate using a 100Ω load. This paper further describes the design considerations of the thyristor gate drive circuits and discussed the operation of the magnetic core with respect to its placement in the SSMG's structure. Based on experimental results, the proposed configuration is a practical method for improving pulse rise time in thyristor based SSMGs.

Organ-on-chip (OoC) systems enable the recapitulation of key structural and functional characteristics of human tissues within controlled micro-engineered environments. In mechanically active tissues such as musculoskeletal, cardiac, and vascular systems, the incorporation of dynamic physical forces is essential for replicating the biomechanical cues governing cellular morphology and functional responses in-vivo. Without such stimuli, OoC models may fail to capture physiologically relevant tissue behaviors. Porous and semi-permeable membranes are critical components of OoCs, facilitating selective transport of nutrients, gases, and signaling molecules between cellular compartments to support biologically accurate barrier replication. Hence, fabrication strategies that permit precise modulation of membrane permeability are desirable to accommodate for the varying needs in pore size and porosity across organ systems. This study presents a two-stage fabrication process for stretchable, microporous polydimethylsiloxane (PDMS) membranes using femtosecond (fs-) pulse laser drilling. The laser-ablated pores exhibit a characteristic conical morphology, with diameters tapering from the laser entry to exit point. By modulating laser power and number of pulses, 6–15 μm exit-end pore diameters were achieved in 50 μm thick PDMS films. The membranes demonstrated strong mechanical resilience, with a 5–12% reduction in Young’s modulus after 500 cycles of strain loading. Furthermore, membranes fabricated at lower laser powers exhibited superior retention of elasticity, highlighting the influence of processing parameters on mechanical behavior. Cytocompatibility and permeability assessments confirmed that the membranes supported sustained cell viability and proliferation over at least three days. In size-restricted membrane pore geometries, cellular migration was constrained without any inhibition of biomolecular transport. This selective permeability is critical in multilayer OoC architectures, where a balance between biomolecular diffusion and cellular compartmentalization is necessary to preserve distinct tissue interfaces and functional organization. This work presents fs-laser micro-drilling as a robust and tunable fabrication strategy for producing mechanically resilient, selectively permeable PDMS membranes for physiologically relevant OoC applications.

Bearings in electric motors are exposed to stray currents and shaft voltages, which can accelerate surface damage and reduce service life. This study examines how pulsed direct current (DC) direction affects early-stage degradation in rolling bearings under low-speed operation. A dedicated test rig was used in which the bearing inner and outer rings were connected directly to the positive and negative terminals of a pulsed DC power supply. Unipolar excitation was applied at 20 kHz with a nominal current of 3 A and shaft-voltage peaks of about 3 V for 3 h, with current flowing in only one direction during each test. After testing, the bearings were sectioned and examined by optical microscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results showed that when current flowed from the outer ring to the inner ring, visible electrical discharge machining (EDM)-type damage was mainly found on the outer raceway. When the current direction was reversed, the damaged region shifted to the inner raceway. The affected areas showed crater-like discharge features and surface chemical changes, while the opposite raceway showed much less change under the same test conditions. These observations indicate that current direction influences where EDM-type damage more likely forms in the bearing under the present low-speed unipolar excitation conditions.

Lead-free dielectric films are ideal candidates for pulse power capacitors due to their rapid charge-discharge capability, but their energy storage performance still needs further improvement to meet the requirements of high-performance applications. In this work, 0.84BaTiO3-0.16Bi(Mg0.2Ni0.2Zn0.2Zr0.2Nb0.2)O3-xMn (0.84BT-0.16BMNZZN-xMn)/LaNiO3 (LNO) heteroepitaxial films were successfully fabricated on SrTiO3 (STO) (001) substrates via chemical solution deposition (CSD) technology, and the regulation effects of Mn doping on the films' microstructure, electrical properties, and energy storage characteristics were systematically investigated. The results show that the introduction of Mn ions effectively refines the grain size, improves the leakage behavior of the films, and thus significantly enhances the breakdown strength. When the Mn doping content x = 0.01, the film exhibits optimal energy storage performance: the recoverable energy density (Wrec) reaches 72.3 J·cm-3, the efficiency (η) is 72.6%, and the breakdown strength (Eb) is as high as 5604 kV·cm-1. Meanwhile, the sample demonstrates excellent temperature stability over the wide temperature range of -120 to 120 °C (Wrec = 48.1 J·cm-3 with a fluctuation of less than 2%, @3500 kV·cm-1), and the Wrec changes by less than 2% after 109 cycles, indicating outstanding long-cycle reliability. These results confirm that the 0.84BT-0.16BMNZZN-0.01Mn epitaxial film has broad application prospects in high-power energy storage fields and is a promising candidate material.

Dielectric energy storage capacitors play a pivotal role in pulsed power systems. Herein, we demonstrate a breakthrough in dielectric energy storage by engineering ​local polarization units in high-entropy multilayer ceramic capacitors (MLCCs). By incorporating equimolar Ba2 +/Sr2 + dual cations, we precisely smoothen the phase transition and stabilize a nanoscale phase-coexistence state in an NBT-based matrix, which simultaneously retain robust local polar units while disrupting long-range domain order. This unique configuration, validated by atomic-resolution HAADF-STEM and phase-field simulations, enables a high reversible polarization and breakdown strength. The optimized MLCCs achieve an ultrahigh recoverable energy density of 18.2Jcm-3 with 91% efficiency, coupled with exceptional thermal stability and fatigue resistance. This work establishes a general design paradigm for high-entropy dielectrics for energy storage by controlling local polarization configurations.

Abstract Progress of the ITER Project is summarized and its significance for fusion development highlighted, in light of recent growth in public/private initiatives. Following a series of reforms including reorganization, contract's adjustments, trust renewal with regulator, and repair of key components, the Project has performed with unprecedented schedule/cost efficiency over the past years, under its new Baseline 2024. This baseline is a comprehensive/feasible plan for assembly, integrated commissioning/operation under a stepwise safety demonstration, for earliest delivery of ITER's key objectives indispensable for fusion and only achievable by ITER. Progress on components' first-of-a-kind manufacture and formation of supply chains have been led by the ITER Organization, the seven Member's Domestic Agencies, and their national industries. These achievements include repairs of vacuum vessel (VV) joints and thermal shield cooling pipes, completion of superconducting magnets and of six of nine VV sectors, start of series production of divertor components and gyrotrons, etc. Assembly and installation of VV modules progress with Schedule Performance Index above 1, with three sectors installed in final position by Nov. 2025. Commissioning of plant systems, including cooling water, pulsed power electrical switchyard, and world’s largest cryoplant, is going well. A new magnet cold test facility is nearing completion with operation starting in winter 2025. In the Neutral Beam Test Facility, SPIDER achieved record current density, and MITICA installation is progressing as planned. In the Baseline 2024, the first operational phase provides scientifically meaningful research including deuterium H-mode and full magnetic energy operation in L-mode. Towards these goals, extensive integrated plasma modelling has been carried out. These studies in collaboration with Members' institutes, have led to adoption of the tungsten first wall concept. Reflecting on recent developments in fusion, we reconsider ITER’s mission and objectives in the framework of remaining challenges for fusion to become a practical source of electric power.

Glass ceramics are supposed to offer the potential of retaining the high permittivity of ceramics, and at the same time exhibiting high dielectric breakdown strength (DBS), thus producing high dielectric energy storage performance in bulk material. Nonetheless, to date, it still remains a big challenge to achieve high energy storage density in glass ceramics compared to other dielectric energy storage materials. Herein, we conceived and fabricated a new type of BaTiO3-based glass ceramics with nanoscale polymorphic structure in a single nano-grain formed by Ge-ions simultaneous substitution of A and B sites during crystallization. It has been found that appropriate GeO2 doping concentration will form nanoscale spontaneous polarization vortex domains in a single nano-grain, which enhances polarization, efficiency, and DBS. As a result, excellent energy storage performance is achieved, with a high recoverable energy density (Wrec) of 10.08 J cm-3 with high energy storage efficiency of 91.3% and high charge-discharge energy storage density (Wd) of 8.84 J cm-3 under 1500kV cm-1. It also exhibits ultrahigh hardness (10.2GPa). This work shows the potential applications of BaTiO3-based glass ceramics in high and pulsed power devices and provides a strategy for designing advanced dielectric glass ceramics.

Benchmarking nonlinear controllers for a Quad Active Bridge resonant converter supplying pulsed power loads in DC microgrids

Staged Z-pinch experiment at the double-EAGLE pulsed power facility

Correlating field-induced phase transition with discharge behavior in NaNbO3 ceramics for pulsed power applications