Pulsed Power Applications Research Articles

MoS2 Nanoflakes based Kilohertz Electrochemical Capacitors

AbstractAn ultra‐fast electrochemical capacitor (EC) designed for efficient ripple current smoothing was fabricated using vertically oriented MoS2 (VOM) nanoflakes deposited on freestanding carbonized cellulose (CC) sheets as electrodes. The daily used cellulose tissue sheets were transformed into electrode scaffolds through a rapid pyrolysis process within a preheated furnace, on which VOM nanoflakes were formed in a conventional hydrothermal process. With these ~10 μm thick VOM‐CC electrodes, ultrafast ECs with tunable frequency response and specific capacitance density were fabricated. The ECs with a cell‐level areal capacitance density of 0.8 mF/cm2 at 120 Hz were demonstrated for ripple current filtering from 60 Hz to 60 kHz. At a lower frequency response level, EC cell with a large capacitance density of 4.8 mF/cm2 was also demonstrated. With the facile and easily scaled up process to producing the nanostructured electrode, the miniaturized VOM‐CC based ECs have the potential to substitute the bulky aluminum electrolytic capacitors for current smoothing and pulse power applications.

Analysis and Design of a Novel LLC CCPS for Repetitive Pulsed Power Applications

This paper presents a novel type of capacitor charging power supply (CCPS) based on LLC resonant DC/DC converter for repetitive pulsed power applications, such as pulsed lasers. Because the load of CCPS is almost capacitive, leading to a quickly varying of output voltage during the charging period, conventional methods are not appropriate and not accurate enough for analyzing the transient characteristics of this proposed LLC CCPS. Thus, an equivalent resistance method based on first harmonics analysis (FHA) method is proposed and parasitic capacitor effect is analyzed too. In order to improve the stability and robustness of the current control system of the proposed LLC CCPS, a PI+LPF type controller combining LUT-based feed-forward is applied. Based on the theories above, a prototype with 200V input and maximum 1kV/2kW output is demonstrated. A peak efficiency of 97.85% and 2A peak average output charging current is achieved and experiments of repetitive pulsed power with 1Hz are carried out. The results prove the superiority of the proposed LLC CCPS. This text explores new topology options for CCPS and aims to improve their performance, the proposed LLC CCPS shows great engineering application value and potential on repetitive pulsed power applications.

Achieving Ultrahigh Energy Storage Performance for NaNbO3-Based Lead-Free Antiferroelectric Ceramics via the Coupling of the Stable Antiferroelectric R Phase and Nanodomain Engineering.

NaNbO3(NN)-based lead-free eco-friendly antiferroelectric (AFE) ceramics with an extremely high maximum polarization (Pm) are believed to be a promising alternative to traditional lead-based ceramics. Nevertheless, the high energy dissipation resulting from the large polarization hysteresis, which arises from the AFE-ferroelectric (FE) phase transition, poses a great challenge to the application of this promising ceramic. Herein, an excellent recoverable energy storage density (Wrec) was attained by intentionally designing a (0.86 - x) NaNbO3-0.14CaTiO3-xBiMg2/3Nb1/3O3 (NN-CT-xBMN) relaxor antiferroelectric ceramic, attributed to the synergistic effect of the stable AFE R phase and nanodomain engineering to overcome the bottleneck. The obtained results illustrate that the inclusion of BMN causes the transition from AFE microdomains to nanodomains and stabilizes the relaxor AFE orthorhombic R phase, which generates a highly stable polarization field response with low hysteresis and delays the AFE-FE phase transition, thus improving energy storage density. As a consequence, a high Wrec of 5.41 J cm-3 with an excellent conversion efficiency η of 86.7% was obtained in the NN-CT-0.08BMN ceramic. Moreover, the NN-CT-0.08BMN ceramic exhibits superior stability in temperature (25-150 °C), frequency (1-600 Hz), and fatigue behavior (10°-104 cycles) together with a large current density (CD = 810 A cm-2), ultrahigh power density (PD = 118 MW cm-3), and ultrafast discharge rate (t0.9 < 0.7 μs). This superior energy storage density, coupled with outstanding stability, suggests that the NN-CT-0.08BMN ceramic has the potential to be a promising candidate for pulsed power applications and power electronics.

Excellent energy storage performance of Mn-doped SrTiO3-BiFeO3 thin films by microstructure modulation

Dielectric thin film capacitors are expected to be a promising candidate for high-performance energy storage devices due to their high power density, fast charge/discharge speed, and excellent stability. Nevertheless, it remains a challenging endeavor to develop dielectrics with excellent energy storage density comparable to that of commercial batteries. In this work, lead-free 0.8SrTiO3-0.2BiFeO3 (0.8STO-0.2BFO) thin films with coexisting amorphous and nanocrystalline structure were prepared by a sol-gel method. The heat-treatment temperature was adjusted to form polar-nano regions, thereby modulate the breakdown strength and dielectric polarization, and increase the energy storage density. The electric potential, electric field, and current density of the films with different amorphous/crystalline volume fractions were evaluated by the finite element simulation to further verify that the proper crystallization can result in the improved polarization performance and increased breakdown strength of the films, which are beneficial to the enhancement of energy storage performance. Through structural tailoring, the 0.8STO-0.2BFO film annealed at 550 °C demonstrates the optimal energy storage properties with a giant discharge energy storage density of 65 J/cm3 and high efficiency of 75% at room temperature. Simultaneously, a broad temperature stability (20–160 °C), superb operating frequency stability (20 Hz-2 kHz), and excellent fatigue endurance (6.3 ×105) are observed without appreciable degradation of the energy storage performance. The excellent energy storage performance indicates a widespread potential of 0.8STO-0.2BFO films in pulse power applications, such as consumer electronics, microelectronics, and medical devices.

Tailoring Phase Fraction Induced Saturation Polarization Delay for High-Performance BaTiO3-Based Relaxed Ferroelectric Capacitors.

Electrostatic capacitors based on dielectric materials are essential for enabling technological advances, including miniaturization and integration of electronic devices. However, maintaining a high polarization and breakdown field strength simultaneously in electrostatic capacitors remains a major challenge for industrial applications. Herein, a universal approach to delaying saturation polarization in BaTiO3-based ceramic is reported via tailoring phase fraction to improve capacitive performance. The ceramic of 0.85(0.7BaTiO3-0.3Bi0.5Na0.5TiO3)-0.15Bi0.5Li0.5(Ti0.75Ta0.2)O3 delivers an ultrahigh recoverable energy density (Wrec) of 7.16 J cm-3 along with an efficiency (η) of approximately 90% at a breakdown electric field of 700 kV cm-1, outperforming the current BaTiO3-based ceramics and other lead-free ceramics. Meanwhile, the Wrec and η exhibit wide frequency, temperature, and cycling fatigue stability. Additionally, both an extremely fast discharge time of 115 ns and a large power density of 106.16 MW cm-3 are concurrently attained. This work offers a promising pathway for delaying saturation polarization design in order to create scalable high-energy-density ceramics capacitors and highlight the research prospects of pulse power applications.

Suppression of the ferroelectric phase for (K0.5Na0.5)NbO3 ceramic by A/B-sites disorder for enhancement the energy storage properties and dielectric breakdown strength

In the present study, we propose a new strategy called suppression ferroelectricity of (K0.5Na0.5)NbO3 (KNN) lead-free ceramics for significant enhancement of energy storage properties (ESPs) and dielectric breakdown strength (DBSs). Both of pure KNN and (Na0.6Ag0.1Bi0.1)(Nb0.8Ti0.25)O3 (abbreviate NN-ABT) were synthesized using solid reaction technique. The crystal structure, dielectric and ferroelectric properties of both prepared ceramics were investigated. NN-based ceramics shown ferroelectric to relaxor phase crossover with pseudo-cubic crystal structure at ambient temperature. Present relaxor phase is attributed to substitution of monovalent (K1+) by trivalent (Bi3+) which can cause A-site cation vacancies and charge misfit of KNN lattice. The inhabitation of grain size to sub-micrometer observed by scanning electron microscope and this could be attributed to the lower ionic radius of (Ag1+ = 1.15 Å) and (Bi1+ = 1.38 Å) compared to (K1+ = 1.64 Å) which can suppressed the tolerance factor (τ) from 1.01 for KNN (ideal ferroelectric phase) to τ = 0.85 for NN-ABT . Suppression of the (τ) value can enhanced the degree of the relaxor phase, while inhibition of grain size can improved the DBSs or Eb. Superior enhancement of energy storage properties were achieved in NN-based ceramic due to hybridization between Bi3+ 6 P and O2- 2 P orbitals instead of K1+ 1 S and O2- 2 P orbitals which resulting in increasing the maximum polarization. The results shown that (NN-ABT) is acquired the preeminent of recoverable energy storage density Wrec ∼ 11 J/cm3, energy storage efficiency (ƞ = 89%) at E = 550 kV/cm. Furthermore, the sample shown an excellent thermal and frequency stabilities variation in a wide range of temperature (25–175 °C) and frequency (2–50 Hz). The significant enhancement in energy storage performance of NN-ABT ceramic is attributed to disturb the ferroelectric phase of KNN and forming PNRs of relaxor phase at ambient temperature. Therefore, the present study provides a good guideline for optimizing the ESPs and DBSs of NN-based ceramics to be more applicable for pulsed power and energy storage applications.

Structural, dielectric, and morphological properties of (1-x)Ba0.65Sr0.35TiO3-xBi(Mg2/3Nb1/3)O3

Compared to other electrical energy storage devices, dielectric capacitors provide advantages like high power density, fast charge and discharge times, thermal stability, excellent mechanical strength, and a long cycling lifetime. Amongst the various dielectric materials, relaxor ferroelectric materials offer low remanent polarization and high energy efficiency. Previous research has shown that (i) doping Bi3+ ions into perovskite material can achieve improved results because its valence electronic configuration is close to that of Pb2+ and its ionic radius is also comparable to that of Ba2+, and (ii) introducing complex ions at the B-site can reduce the long-range ferroelectric order and result in the occurrence of polar nano regions.The present work aims at (i) incorporating both these strategies for the synthesis of the dielectric ceramic material and (ii) studying the structural, morphological, and dielectric properties of the prepared material. We have successfully synthesized (1-x) Ba0.65Sr0.35TiO3 – x BiMg2/3Nb1/3O3 with the help of a conventional solid-state reaction technique. The XRD analysis demonstrates the formation of cubic perovskite structure with space group Pm3m. The diffraction peaks shift towards lower 2θ angles with an increasing concentration of BMN, indicating a regular increase in unit cell volumes owing to the substitution of the smaller Ti4+ ions with bigger Mg2+ and Nb5+ ions. FESEM images illustrate the development of a homogeneous and dense microstructure. Element mapping analysis confirms the uniform distribution of all the elements within the prepared sample. From the dielectric measurements, we found that with the increase in doping, the dielectric peak broadens, and the frequency dispersion increases, indicating a rise in the relaxor behavior, which may be attributed to the increase in cation disorder due to the substitution of Bi3+ and [Mg2/3Nb1/3]4+ at the A- and B-site, respectively. The excellent dielectric properties indicate that (1-x)BST-xBMN is a promising ceramic material for use as a dielectric in capacitors for advanced pulsed power applications and consumer electronic devices.

Study on discharge characteristics of pulsed power module under the condition of discharge short circuit fault

Efficiency and safety are key factors that must be emphasized in pulsed power applications. The discharge characteristics of pulsed power supply directly determine the performance of the railgun. This paper conducts a research on short-circuit faults in transmission coaxial cables of pulsed power supply. In order to study the effect of short-circuit fault on the discharge characteristics of pulsed power supply and system efficiency,a pulse-forming network with cable short-circuit failure and dynamic railgun model are established in the paper. The effect of short-circuit fault on peak current is discussed by simulation. The results show that the short-circuit fault currents are all higher than the currents under normal conditions, and the closer the short-circuit location is to the power supply side, the higher the peak value of current is. In some extreme case, the peak fault current exceeds 1.5 times the normal, which requires consideration of short-circuit fault protection measures, such as the addition of a DC circuit breakers.

0.98[(Na(1–x)/2Smx/2Nb0.3TiO3)] + 0.02MnO2 Lead-free Ceramic System Design; An antiferroelectrics with Improved Relaxation Behavior

The sodium niobate-based ceramics 0.98[(Na(1−x)/2Smx/2Nb0.3TiO3)] + 0.02MnO2 acronymed NSmNT of different compositions (x = 0.05, 0.1, 0.11, 0.12, and 0.13) were prepared via solid-state reaction method. The prepared samples were characterized by XRD to study the phase structure of the designed systems, SEM to study the microstructure properties of the NSmNT ceramics. In addition to that LCR meter was used to measure the sample temperature-dependent dielectric permittivity, dielectric loss, and systems impedance. The results showed an increment in the dielectric breakdown strength (DBS) with increasing x content from 100 kVcm–1 to 450 kVcm–1. Similarly, the high recoverable energy density (Wrec) of 5.61 J cm–3 was obtained for x = 0.11 symbolized (NSmNT2) with an exquisite efficiency of 88%. The study also analyzed the complex impedance of the NSmNT2 ceramics system to clearly understand the dielectric behavior of the system in question. A general view of things considers the NSmNT2 ceramic system to be a reliable system for pulsed power applications.

High comprehensive energy storage properties in (Sm, Ti) co-doped sodium niobate ceramics

Ceramic capacitors are ubiquitously used in high power and pulse power applications, but their low energy density, especially at high temperatures (&amp;gt;150 °C), limits their fields of application. One of the reasons is the low energy efficiency under high electric fields and/or at high temperatures. In this work, equimolar Sm3+ and Ti4+ cations were doped in NaNbO3 to increase relaxor characteristics and energy storage properties. The optimal recoverable energy density Wrec of 6.5 J/cm3 and energy efficiency η of 96% were attained in the ceramics with 10% (Sm, Ti) concentration (SmT10). Dense microstructure and low dielectric loss were attributed to the high energy storage performance. Impedance spectra analysis revealed that the grain boundary resistance dominates at low temperatures, while the grain resistance dominates at high temperatures. The ceramics show stable Wrec and η in a broad temperature range of −90 to 200 °C and repeated charge–discharge cycles up to 105. The comprehensive energy storage performance indicates SmT10 ceramics are among potential candidates for ceramic capacitors working at high temperatures.

The Influence of BaTiO3 Content on the Energy Storage Properties of Bi0.5Na0.5TiO3-Bi(Mg2/3Nb1/3)O3 Lead-Free Ceramics

Na0.5Bi0.5TiO3 (NBT)-based ceramics are promising lead-free candidates for energy-storage applications due to their outstanding dielectric and ferroelectric properties derived from large polarization. However, the high coercive field and large remnant polarization are unfavorable for practical applications, and thus NBT-based ceramics with relaxation behavior via doping/forming solid solutions with other elements/components have been widely studied. In this work, BaTiO3 (BT) was introduced to the 0.94Na0.5Bi0.5TiO3-0.06Bi(Mg2/3Nb1/3)O3 system by a conventional solid-state reaction to form a homogeneous solid solution of 0.94[(1−x)Na0.5Bi0.51TiO3-xBaTiO3]-0.06Bi(Mg2/3Nb1/3)O3 (BNT-100xBT-BMN). As the BT content increased, the proportion of the rhombohedral R3c phase increased while that of the tetragonal P4bm phase decreased, leading to the maximum Pmax (38.29 μC/cm2) and Eb (80 kV/cm) obtained in BNT-7BT-BMN (x = 0.07) composition. Specifically, the optimal energy storage properties of Wrec ~ 1.02 J/cm3 and η ~ 62.91% under 80 kV/cm were obtained in BNT-7BT-BMN ceramics, along with good temperature stability up to 200 °C, which are promising factors for future pulse power applications.

Design and testing of a high perveance sheet beam electron gun

This paper presents the design, prototype engineering, and initial testing of a relatively low-voltage, high aspect ratio electron gun for versatile pulsed power applications. The sheet beam, diode electron gun is designed for (23–25) kV voltage and 6 µA/V1.5, as is required for x-band klystron, as a part of a compact Klylac delivering electron beam energy in the MeV range. The gun prototype was engineered, built, and tested using a Scandinova M1-0.5 modulator. Beam loss on the anode aperture is evaluated from transient waveforms and equivalent circuit modeling.

Multilayer Ceramic Capacitors: An Overview of Failure Mechanisms, Perspectives, and Challenges

Along with the growing of population and social and technological improvements, the use of energy and natural resources has risen over the past few decades. The sustainability of using coal, oil, and natural gas as the main energy sources faces, however, substantial obstacles. Fuel cells, batteries, and super-capacitors have the highest energy densities, but due to their high-power density and rapid charge-discharge speed, regular dielectric capacitors are becoming more popular for pulsed power applications. High electric breakdown strength and high maximum but low-remnant (zero in the case of linear dielectrics) polarization are necessary for high energy density in dielectric capacitors. The high performance, multi-functionality, and high integration of electronic devices are made possible in large part by the multilayer ceramic capacitors (MLCCs). Due to their low cost, compact size, wide capacitance range, low ESL and ESR, and excellent frequency response, MLCCs play a significant role in contemporary electronic devices. From the standpoint of the underlying theories of energy storage in dielectrics, this paper emphasizes the significant problems and recent advancements in building extremely volumetric-efficient MLCCs. Following a thorough examination of the state-of-the-art, important parameters that may be used to improve energy-storage qualities are highlighted, such as controlling local structure, phase assembly, dielectric layer thickness, microstructure, conductivity, different failure modes, and the specific performance during the failure mechanism. The summary of some conclusions on the impending need for innovative materials and diagnostic methods in high-power/energy density capacitor applications appears at the end of the paper.

Role of Electrode Geometry on the Operational Characteristics of Multiaperture Pseudospark Switch

In the present study comparative analysis for various geometrical parameters has been presented for the operational characteristics in a single gap multiaperture pseudospark switch (PSS). The investigation has been carried out to understand the importance of geometrical parameters on the behavior of the discharge properties of PSS by using 2-D axis-symmetric kinetic simulation tool COMSOL Multiphysics. The primary attention of the study is to show the effect of multiple apertures, baffles, and chicane on the performance of PSS. The analysis has clearly explained the axial, radial, and transient discharge behavior with the penetrating potential in the PSS. It is found that the single gap geometry of PSS with multiaperture, baffle, and chicane has fast switching, higher hold off and higher current carrying capability with long life due to less erosion. In this respect, the analysis has also explained the discharge properties in a single-gap multiaperture PSS with baffles, such as potential penetration inside the PSS for hydrogen gas at different pressures and applied voltages. Along with this, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}$ </tex-math></inline-formula> characteristics of the same type PSS geometry with baffles and chicane have also been determined by experiment. The obtained results are very much useful for understanding and optimization of the geometrical and operational characteristics of a multiaperture PSS suitable for pulse power applications.

Accumulation effect of active species in atmospheric-pressure plasma jet driven by nanosecond high-voltage pulses with MHz pulse repetition rate

With respect to successful applications of pulsed power in gas discharges, the enhanced generation of desired active species and control of plasma parameters as required are always decisive issues. In this study, a bipolar nanosecond high-voltage pulse generator with a maximum pulse repetition rate (PRR) of up to 1 MHz (i.e. a minimum pulse interval of 1 µs) in burst mode is developed, based on the principle of full-bridge converter and pulse transformer. This pulse source is used to generate an atmospheric-pressure plasma jet in Ar + 1%CH4 gas flow, and the influence of pulse intervals (from 1–10 µs) is explored. It is found that the pulse interval can strongly modulate the active species, i.e. a short pulse interval enhances the generation of C2 radial and H atom due to the accumulation effect, when the pulse interval is comparable with their lifetime, while it slightly suppresses the generation of Ar excited states and the energy fraction into electronic excitation. Reduced pulse intervals also prominently increase the energy fraction of vibrational excitation. This study demonstrates how the PRR effectively modulates active species and energy branching and enhances the generation of certain active species in atmospheric-pressure plasma driven by pulsed power.

Multi-scale collaborative optimization of SrTiO3-based energy storage ceramics with high performance and excellent stability

SrTiO3 (ST)-based ceramics are considered as promising candidates for energy storage applications. However, the low polarization intensity in ST-based materials limits their energy storage performance, rendering materials that usually exhibit a low recoverable energy-storage density. In the present study, we have optimized the energy storage performance of ST-based ceramics by using a combined optimization strategy of structural engineering and microstructural regulation. High performance (Sr1-x-y-2φNayBixCaφ□φ)TiO3 (abbreviated as zSNBCT, where □ represents the Sr vacancies) ceramics were thereby designed. During composition optimization, the phase state of zSNBCT was adjusted to a critical point where the relaxor ferroelectric-paraelectric phase transition occurred around room temperature. It thus induced a strong relaxation behavior with the formation of ferroelectric polar nano-regions, yielding a high recoverable energy-storage density (Wrec) of ∼6 J/cm3 and a high energy-storage efficiency (η) of ∼92% under a large breakdown electric field of 440 kV/cm, for z = 0.2 sample. Moreover, the breakdown strength (BDS) of the 0.2SNBCT ceramic was further improved by adopting a two-step sintering and spark plasma sintering approach for the microstructural refinement. Simulation models containing grains and grain boundaries were well established using phase-field simulation and finite element analysis. These simulations came to a similar conclusion for the enhanced BDS. Namely, the fine-grained microstructure significantly hindered the growth of breakdown cracks under an applied electric field. Most importantly, the 0.2SNBCT sample showed excellent frequency stability (1−1000 Hz), thermal stability (20−140 °C), and cycling stability (105 cycles), rendering it a promising candidate for energy storage systems. Our designed strategy of structural engineering and microstructural regulation may provide a new paradigm for the design of high-performance energy storage ceramics for pulse power applications.

Modeling of the Transient Electric Field in Multilayer Dielectric Composites Under Impulsive HV Energization

This article presents the theoretical analysis of composite electrical insulation, formed from layered dielectric materials and subjected to impulsive energization. The 1-D planar and cylindrical geometries were considered, consisting of an arbitrary number of layers with arbitrary relative permittivity and electrical conductivity. Analytical solutions have been successfully derived for the time-dependent electric field inside the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${i}$ </tex-math></inline-formula> th layer. To demonstrate the usage of the model under complex multilayer topologies where analytical solutions are nontrivial, the characteristics of a 20-layer-graded composite under microsecond and sub-microsecond impulses were analyzed and validated against a finite-element (FE) solver. Results indicate that the transient electric field response under impulsive energization is strongly dependent on the interplay between the composite relaxation time constants and the characteristic timescales associated with the applied impulse. The model is a further development for the design and coordination of functionally graded materials (FGMs) and composite insulation for high-voltage (HV) system design. This is particularly relevant under fast-rising impulsive conditions as often encountered in many pulsed power applications.

Study on Transient Turn-On Characteristics of Pulse Power Thyristor-Type Devices Under Ultrahigh di/dt Condition

Specially optimized thyristor-type devices for fast turn-on and high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{d}{i}/\text{d}{t}$ </tex-math></inline-formula> capability are promising in pulse power applications. In this work, the transient turn-on characteristics of MOS-gate triggered and current-gate triggered thyristor-type devices operating at ultrahigh <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{d}{i}/\text{d}{t}$ </tex-math></inline-formula> conditions are first studied. The injected charge transport process is theoretically analyzed and modeled by considering the effect of the transient electric field, during short pulse duration, which then clearly reveals the difference between the MOS-gate triggered and current-gate triggered thyristor-type devices on the transient turn-on characteristics. TCAD simulations and experimental measurements are carried out to verify the transient turn-on process. The theoretical, simulated, and experimental results show that the MOS-gate triggered thyristor has better turn-on characteristics than the current-gate triggered thyristor, which attributes to the reduced turn-on step and consequently stronger conductivity modulation. This work helps further optimization of thyristor-type devices achieving fast turn-on and high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{d}{i}/\text{d}{t}$ </tex-math></inline-formula> capability.

Fast Time Response Full Absorption Faraday Cup and Its Application in the Measurement of Intensive Electron Beam Diodes

A magnetically insulated transmission line (MITL) is an inevitable choice for ultra-high power density energy transmissions. Its working process is complex, with an obvious influence on the working process of electron beam diodes and other load devices. The power coupling process of an electron beam diode driven by an MITL is a difficult problem in pulse power applications. No research is available on the electron beam characteristics of its anode. In this paper, a fast time response full absorption Faraday cup was developed. An intense electron beam measurement waveform showing the multi-stage characteristics was obtained through measurements using the Faraday cup absorber as the anode of the electron beam diode. The stage characteristics of the beam were in good agreement with the vacuum transmission, magnetic insulation formation, and multi-stage process of the stable magnetic insulation. The beam intensity corresponded with the conduction current of the cathode. It was obviously smaller than the current of the anode. The results reflected the influence of the different processes of the magnetic insulation on the transmission line on the beam waveforms in the diode area and provided a reference for the power transmission of the power device and the load system design.

On the Enhancement of Energy Storage Performance in Modified Relaxor Ferroelectric Ceramics for Pulsed Power Applications

Relaxor-type ferroelectrics show important potential in energy storage fields due to their significantly enhanced energy performance and good temperature stability compared to normal ferroelectrics. Here, a novel, high-performance ternary composition, (0.4−x)BiFeO3-xBi(Mg1/2Ti1/2)O3–0.6BaTiO3 (x = 0.2, 0.25, 0.3, 0.35, 0.4), was designed by compositional modulation, which displays typical relaxor characteristics. The optimum energy storage properties can be attained at x = 0.35, accompanied by energy efficiency of 84.87%, a promising energy storage density of 2.3 J/cm3 and good temperature stability of less than 10% over 20–160 °C. Moreover, the samples provide stable cycling fatigue after 105 cycles and a fast discharge time of t0.9 &lt; 0.1 μs, indicative of promising applications in energy units.