Search

In this paper, a wideband polarization reconfigurable omnidirectional antenna (PROA) based on a single-substrate active metasurface is proposed. By controlling the states of the PIN diodes, the antenna can selectively radiate an omnidirectional linearly polarized wave and an omnidirectional circularly polarized wave. The reflection coefficient, axial ratio (AR), radiation pattern, and gain of the proposed antenna have been analyzed from the perspective of simulation and measurement. The measured results show that the PROA has a wide overlapped bandwidth from 2.87 to 3.67 GHz (relative bandwidth 24.46%). To the authors' best knowledge, this is the first reported wideband PROA based on a single-substrate reconfigurable polarization converter. This study not only offers a novel approach to design PROAs, but also greatly reduces the design complexity of the feed source compared with the traditional design method of PROAs. [ABSTRACT FROM AUTHOR]

The operating bandwidth of miniaturized magnetoelectric (ME) antenna is generally narrow due to the acoustic wave driven magneto-electromechanical resonance effect, parallel connection of multiple ME antennas with different resonant frequencies is an effective way to broaden the operating bandwidth of the antenna. This paper presents an ME antenna array consisting of three units, which are constructed of a sandwich stack of Metglas/Pb(Mg1/3Nb2/3)O3–PbTiO3/Metglas. The −3 dB operating bandwidth of 152.4–172.8 kHz is achieved, and the relative bandwidth is 12.5%. Experimental results indicated that the bias magnetic field and coupling effect between the ME antenna units significantly influence the performance of ME antenna array. A modified Butterworth–Van Dyke (MBVD) equivalent circuit model is used and improved to analyze the influence of sound waves, electric fields, magnetic fields, parasitic capacitance, and bias magnetic field on the ME antenna array. The simulation results of the MBVD equivalent circuit model are agreed well with the experimental results. The improved MBVD model is beneficial for the design of acoustic wave driven antenna array. [ABSTRACT FROM AUTHOR]

The utilization of polarization conversion metasurfaces (PCMs) has enormously facilitated the capabilities of numerous wireless systems and optical devices. However, the cross‐polarization conversion performed by the PCM inevitably results in a parasitic filtering effect that severely hinders its capacity to receive multiple polarization waves. In this paper, a high‐efficiency transmissive PCM based on the non‐reciprocal metasurface integrated with the NPN transistors is proposed, which can convert both input x‐ and y‐polarized waves into the y‐polarized transmitted wave, meanwhile, the parasitic filtering effect of the polarization converter is effectively eliminated. The total transmission efficiency of orthogonal polarizations is higher than 50% within 3.26–3.39 GHz, excluding the gain from the transistor‐based circuits, and the peak efficiency reaches 85.4% at 3.35 GHz. In addition, the proposed PCM opens up the possibilities for expanding the range of received polarization states. For the conceptual demonstration, the conversion from arbitrary linear polarizations to y‐polarization has been achieved with the transmission coefficients higher than ‐0.66 dB at 3.35 GHz. The performances of designs have been verified by experiments and tests. These designs show potential for breaking the constraints on multiple polarization conversion and promoting the development of versatile PCMs. [ABSTRACT FROM AUTHOR]

The realization of dynamic polarization rotation based on the metamaterial or metasurface is always a concerned issue in electromagnetic manipulation. In this Letter, a transmission-type switchable metasurface is proposed, which can rotate the linear polarized (LP) wave to arbitrary angle among ±45° in a wide frequency band. The polarization rotation metasurface (PRM) consists of a polarization conversion surface and a partially reflective surface. By controlling the resistances of PIN diodes, the PRM can change the polarization angle of transmitted LP wave. To verify the design, a prototype of the proposed PRM is fabricated and tested, and the simulated and measured results are in good agreement. According to the measured results, the fractional bandwidth at each state of prototype is larger than 20.4%. The overlapping operational band of the prototype is from 3.03 to 3.60 GHz, where the transmission coefficient remains higher than –2 dB, and the axial ratio of transmitted wave is higher than 15 dB. The proposed design may have the application potential in target detection, wireless communication, and polarimetric imaging. [ABSTRACT FROM AUTHOR]

This paper presents a novel method to improve the working bandwidth and radiation intensity of piezoelectric antenna by using external circuit. This method makes the piezoelectric antenna combined with roles of high radiation intensity and multiple resonant frequencies without changing the structural size of the piezoelectric antenna. The experimental results show that, compared with the original piezoelectric antenna, the tuning range of the resonant frequency of the piezoelectric antenna caused by the series capacitance and inductance is +13.6 and −24%, respectively. The series inductance will produce new resonance frequency, which provides a new method for the multi-band operation of the piezoelectric antenna. The LLC (series and parallel circuit) composite circuit can increase the number of resonant frequencies of the piezoelectric antenna from 1 to 3, and the S11 at the resonant frequencies are all lower than −10 dB, and the radiated magnetic field of the piezoelectric antenna is increased by 42.3% at least. This method makes the piezoelectric antenna have the dual functions of high radiation intensity and multi-band, which has great significance for broadening the application field of piezoelectric antenna. [ABSTRACT FROM AUTHOR]

We present a transmission-type polarization conversion metamaterial (PCM) whose functions can be dynamically switched among the linear-to-circular (LTC) and linear-to-linear (LTL) polarization conversions. The proposed PCM consists of a grating, a polarization conversion surface and a reconfigurable polarization selective surface incorporated with PIN diodes. By changing the states of diodes, the PCM can achieve the reconfigurable manipulations for incident waves. The Fabryâ€"PĂ©rot (Fâ€"P) resonances excited by the PCM contribute to the polarization conversions, as is illustrated. Moreover, through establishing the Fâ€"P-like cavity model and analyzing the electric field components of the transmitted waves, the conditions for realizing LTC polarization conversion are revealed, which can guide the construction of PCM. The prototype of PCM is fabricated and measured, which can achieve LTC and LTL polarization conversions within 3.31â€"3.56 GHz and 2.76â€"4.24 GHz, respectively, the polarization conversion ratios of two functions are higher than 0.95. The measurement results are in agreement with the simulation data. [ABSTRACT FROM AUTHOR]

In this paper, a wideband and wide-angle transmissive linear-to-circular polarization converter (LCPC) working in the C, X and Ku bands is proposed, which is based on a single-layer dielectric substrate. In order to increase the axial ratio bandwidth of the single-layer LCPC, a method of combining infinite length metal strips and horizontal strips is proposed, which cannot only improve the passband, but also realize large phase difference conversion. The single-layer LCPC with small size is designed and optimized, which can maintain axial ratio stability in the ultra-wide band over large incident angles. When the linear polarized (LP) wave is normal incident, the 3 dB axis ratio bandwidth of LCPC is 6.41–15.07 GHz (relative bandwidth 80.63%). When LP wave oblique incident along the yoz plane, the axial ratio bandwidth will increase with the increase of the incident angle, it is worth noting that when the incident angle reaches 45°, its 3 dB axial ratio bandwidth can reach 100.6%. Moreover, when LP wave oblique incident along the xoz plane, the insertion loss is always less than 3 dB within the working bandwidth, and the incident angle can even reach more than 70°. The measured results are in good agreement with the simulated ones. The LCPC can be widely used in multi-beam antenna, beam scanning antenna and satellite communication. [ABSTRACT FROM AUTHOR]

A novel high-temperature superconducting (HTS) thin-film device based on double-sided YBa2Cu3O7–x (YBCO) thin film, combined with roles of transformer and overcurrent limiter, is proposed and tested in this article. Due to the effective improvement on the power density, operating frequency, repeatability, functional integration, and low profile of the high-frequency converters, thin-film transformer (TFT) has been widely employed in power conversion fields. In contrast to the normal conductive materials, the surface resistance of the HTS materials is much smaller. Thus, the TFT fabricated by HTS thin film has lower Joule losses and higher power conversion efficiency. We designed the double-sided YBCO thin-film-based HTS-TFT and measured its parameters at liquid nitrogen (LN2). As a comparison, we also developed the copper (Cu) based TFT and measured the same parameters at LN2 and room temperature. Besides, we also tested the overcurrent limiting performance of the HTS-TFT, which is based on the state change from superconductivity to normal state. It can be found from the contrastive experiments that the HTS-TFT has better operating parameters than the Cu-TFT; meanwhile, the overcurrent can be limited by the HTS winding effectively. [ABSTRACT FROM AUTHOR]

This article presents a novel method to design a linear-to-circular polarization converter (LCPC) by using a hybrid array structure, which is composed of meander lines and the split ring resonators (SRRs). The LCPC can respond to both the $E$ -Field and $H$ -Field for the incident wave. When the meander line and the SRR are placed along two orthogonal directions, the composed unit cell would have different electromagnetic response characteristics in the two orthogonal directions. Using this method, two LCPCs working in frequency bands of 6–18 and 2–6 GHz are designed, respectively. The simulated results show that for the LCPC working in 6–18 GHz, the axial ratio (AR) is lower than 3 dB in 6.8–17.32 GHz with a maximum insertion loss (IL) of 1.25 dB. When the angle of incident wave is less than 45°, the 3 dB AR bandwidth is 7.87 GHz. For the LCPC working in 2–6 GHz, the AR of entire frequency band is all lower than 3 dB and the maximum IL is 0.82 dB when the incident angle increases to 15°. Even at incident angle of 45°, the bandwidth with the function of polarization conversion is 3.5 GHz. Experiments on the LCPC (6-18 GHz) are carried out, and the measured results are in agreement with the simulated ones, which proves that the LCPCs design method proposed in this paper is effective and reliable. [ABSTRACT FROM AUTHOR]

Inductive pulsed power supply (IPPS) is considered as an alternative to capacitive one due to its higher energy density. An opening switch is necessary for an IPPS because it interrupts the charging circuit and transfers the stored energy to the load. A major technical challenge inherent to the IPPS is the overvoltage across the opening switch, i.e., the open-circuit voltage. Moreover, obtaining a larger current, especially with a steeper rising edge, will further increase the open-circuit voltage. A novel IPPS based on a three-winding pulse transformer, consisting of two primary windings and one secondary winding, is presented in this article to improve the output current and reduce the open-circuit voltage. The two primary inductors adopted a parallel switching scheme, namely, series charging and parallel discharging. Its working principle is analyzed first in detail. The theoretical analysis and simulation results have verified the superiority of the novel IPPS in improving the output current and reducing the open-circuit voltage. [ABSTRACT FROM AUTHOR]

In the launch process of the multistage synchronous induction electromagnetic launcher (SIEL), the armature is usually accelerated step by step. Due to the impact of high instantaneous electromagnetic force and large acceleration fluctuation, some kinds of sensitive loads may be damaged during the launching process. To reduce the harm that caused by the abovementioned issue, this article proposes an optimized armature and an asynchronous pulse discharge scheme to smooth the acceleration curve based on the toroidal reconnected electromagnetic launcher (TREL). First, a mathematical coupling model of the single-stage TREL is built to describe the energy conversion relationship between the driving coils and the armature. Then, the dynamics characteristics of the TREL model based on two armature structures and two discharge schemes are analyzed through the finite-element method. Finally, the simulation results demonstrate that the large acceleration fluctuation of the armature can be effectively cut down with the proposed methods. [ABSTRACT FROM AUTHOR]

A novel thin film transformer based on double sided YBa2Cu3O7−x (YBCO) thin films with high operating performance, named a high temperature superconducting thin film transformer (HTS-TFT), is proposed and tested. In this paper, we designed and fabricated four different types of HTS-TFT based on double sided YBCO thin film and measured their respective operating parameters (including winding resistance, winding inductance, coupling coefficient, and quality-factor) at liquid nitrogen temperature (LN2, 77 K). As the comparative experiment to the HTS-TFT, we also developed the same four types of copper (Cu)-TFT and measured their parameters at both room temperature (RT, 298 K) and LN2, to evaluate their behavior. It can be found from the comparative experiments between the HTS-TFTs and Cu-TFTs that the HTS-TFTs (in LN2) possess better operating parameters than the Cu-TFTs (in LN2 and RT) and they operate as expected in the power conversion tests. The significance of this work is that the HTS-TFTs can be employed in wireless power transfer systems and other power conversion fields, offering a performance enhancement to power transmission efficiency. [ABSTRACT FROM AUTHOR]

This article presents a new single-stage TL-shaped electromagnetic launcher (SS-TL-EL), which improves the configurations of the driving coil and armature on the basis of the traditional synchronous coil launcher. Compared to the traditional single-stage synchronous electromagnetic launcher (TSSSEL), it can achieve a higher launching efficiency. In this model, due to the configuration of the T-shaped driving coil and L-shaped armature; therefore, there are more parameters can be derived to optimize the model and improve the launching efficiency. The finite-element method is used to simulate the model, and the comparison between TSSSEL and SS-TL-EL is completed under the same inductance, capacitance, capacitance-voltage, and armature mass. The simulation results show that SS-TL-EL has the larger eddy current, radial magnetic field density, and the wider current distribution area. In order to verify this feasibility of the concept, an SS-TL-EL and a TSSSEL were established and tested, and their launching model is simulated and analyzed. The experimental results show that the launching effects of SS-TL-EL are in agreement with the simulation results in general. The comparison of experimental results indicates that SS-TL-EL has a better launching effect than the TSSSEL under the same conditions. [ABSTRACT FROM AUTHOR]

For the energy loss issue of the synchronous induction electromagnetic launcher (SIEL) subjected to the traditional driving circuit, a high temperature superconducting magnet (HTSM)-based energy recovery system is proposed in this article to improve the energy management capability for the SIEL. This energy recovery system is composed of half-wave circuit, HTSM, dc chopper, and three-phase full-bridge inverter. If there is a demand to execute the mission of short-term continuous shooting, the HTSM can convert the reverse energy stored in capacitors into forward energy in preparation for the next shot. If the launch mission has ended and no demand of launch again, the dc chopper and the three-phase full-bridge inverter are used to pump the remaining energy back into the grid. Then, a mathematical model of the energy recovery system is established to verify the effectiveness of the above mentioned schemes. The simulation results show that not only does the energy recovery system can realize the reuse of remaining energy in the continuous shooting mission, but also it can complete the unidirectional energy transfer with the grid in unit power factor. Finally, based on the three-coil reconnection electromagnetic launcher (TCREL), a small test platform is built. The transfer process of the remaining energy from the capacitors to the HTSM and the working performance of the dc chopper are mainly tested in here. The experimental results basically verify the effectiveness of the energy recovery system. [ABSTRACT FROM AUTHOR]

This article puts forward a method based on high-temperature superconducting (HTS) current limiting technology, to improve the overcurrent stability for a battery unit in a superconducting magnetic energy storage (SMES)-battery hybrid energy storage systems (HESS). In contrast to supercapacitors, flywheels and other energy storage systems, SMES-battery HESS possess the technical properties of power capacity, energy, and response speed, among others. Thus, SMES-battery HESS may be utilized to handle power swing, energy transfer, voltage fluctuation, and related transient stability issues. But an overcurrent in a battery unit is harm to its cycle life of the battery. Hence, the internal protection system of the battery unit is used to remove a fault by cutting off its outputs. In this article, a YBa2Cu3O7-X (YBCO) thin film is employed as the protection device to limit the overcurrent in a battery unit. In normal operation, the thin film is in the superconducting state, and its influence on the system can be ignored. An overcurrent will be limited evidently lower than the action threshold of the internal protection system by the quench resistance of the thin film. Therefore, the whole outputs of a battery unit will not be interrupted and restarted. Through the verification experiment carried out in our laboratory, the proposed protection method operated as expected, and the stability, as well as the reliability of the battery unit, could be improved. [ABSTRACT FROM AUTHOR]

This paper deals with the interaction of nanoparticles (NPs) in transformer oil and water in the oil and its effect on the electrical properties of the nanoffuid (NF). The breakdown strength and dielectric spectrum measurements under AC for various concentrations of natural SiO 2 and water in mineral oil were studied. Mineral oil-based SiO 2 NFs exhibit significantly higher breakdown voltage than that of base oil under high water content. However, there is an optimal range of NP concentration and water content for maximum breakdown voltage. The results of dielectric spectrum indicate that the dielectric constants of NFs and base oil are greatly affected by water content. The real relative permittivity of oil samples increases exponentially with water content at decreasing frequency (f≤10 Hz). The imaginary relative permittivity of NFs is less than that of the base oil in all cases. Based the experimental results reported, a model on the interplay between NPs and water in transformer oil is presented. The model can broadly explain the influence of the coexistence of NPs and water on the dielectric properties of transformer oil. [ABSTRACT FROM AUTHOR]

Synchronous induction coilgun (SICG) has attracted more and more attention due to its advantages of simple manufacturing and no physical contact between armature and barrel. The armature, as an important component of SICG, will directly affect the launch speed and energy conversion efficiency. According to the distribution characteristics of eddy current and electromagnetic force, a new structural armature is proposed in this paper. The proposed inner conical armature is characterized by the maximum thickness at the tail end and the minimum thickness at the front end, with a gradual decrease in the thickness along the axial direction. The simulation results reveal that the proposed armature not only increases the mutual inductance between the armature and the drive coil but also enhances the electromagnetic force and weakens the armature capture effect. The experimental results verify that, compared with a traditional armature weighing 56.5 g, the new structure armature weighing 58.0 g enables higher muzzle velocities using the same set of pulsed power supply and drive coil, providing higher efficiency. [ABSTRACT FROM AUTHOR]

A design of high-temperature superconducting bandpass filter based on split-ring resonator (SRR) structures is presented in this paper. The SRR has been considered as a classical element for metamaterials and exhibits characteristics of subwavelength resonator, hence can aid in the compact design of filters. Filter has been simulated and optimized using Sonnet software. The measured results of the filter have good consistency with the simulated results and show good band pass characteristics. The center frequency of the filter measured at 70 K was 2.515 GHz, the rectangle coefficient was 1.22, and the insertion loss was 0.1 dB at the center frequency. [ABSTRACT FROM AUTHOR]

This paper proposes a novel single-stage double-layer saddle multipole field electromagnetic launcher (SSDFEL), which combines the characteristics of reconnection gun to achieve simultaneous linear acceleration and gyroscopic stabilization of the projectile. Since the saddle driving coils are divided into two layers, the magnetic field density inside the launcher is enhanced. The eddy current induced on the inner and outer surfaces of the projectile is greatly changed by the hollow cylindrical projectile with six symmetrical vertical slots twisted at a certain angle, and the projectile is simultaneously propelled to perform rotation motion and linear motion. In this paper, the electromagnetic field finite-element software is used to simulate and calculate this model. The simulation results indicated that the double-layer driving coil distribution has larger axial acceleration force and bigger circumferential torque than that of the single-layer driving coil distribution, the energy conversion efficiency has also been obviously increased, and there is an optimal initial twisted angle, which accelerates the projectile to the peak of rotation. To verify the results, an SSDFEL was established and tested. The experiment results confirm that the rotation performance can be affected by the initial twisted angle and a better launching effect is achieved than a single-layer distribution. In general, the experimental results are in agreement with the simulation results. [ABSTRACT FROM AUTHOR]

High-temperature superconducting pulsed power transformer (HTSPPT) is an important component of superconducting pulsed power supply. Six superconducting coils and four normal conducting coils have been designed and manufactured in our previous work. The six superconducting coils and four normal conducting coils can be assembled into a large HTSPPT to obtain high energy storage. Five arrangement modes are proposed and analyzed in this paper. The self-inductance, coupling coefficient, magnetic field distribution and critical current of the five modes are obtained by finite-element simulation and calculation. The results show that Modes 1, 2, and 4 are feasible. Especially, Mode 1 has the highest coupling coefficient, the largest critical current, the highest energy storage capacity, the lowest capacitor voltage, and the shortest current rise time. As a result, Mode 1 is the best assembly sequence for the HTSPPT. The alternate arrangement of all primary and secondary coils can obtain the highest coupling coefficient and energy storage capacity. [ABSTRACT FROM AUTHOR]

Researches on the synchronous parallel discharge of multimodule pulsed power supply have confirmed that it can output large pulse currents with high amplitude. For electromagnetic railguns, excess current may cause orbital erosion and other problems, and the ideal driving current is rectangular pulse currents. Therefore, the asynchronous discharge of multimodule superconducting pulsed power supply (SPPS) is studied in this paper to reduce the amplitude and increase the pulsewidth for driving an electromagnetic railgun. A toroidal SPPS based on eight coupled high-temperature superconducting pulsed power transformers and a dynamic simulation model of electromagnetic railgun is established. The simulation results show that armature currents with different amplitude and pulsewidth can be obtained by adjusting the trigger delay time of each module. With the increase of the trigger delay time, the amplitude decreases but the pulsewidth increases. With a set of trigger delay time, the asynchronous discharge of the eight-module SPPS can output an approximate rectangular pulse current with amplitude of 126 kA. The armature and projectile with a total mass of 50 g can be accelerated to 346 m/s, giving the efficiency of 16.2%. [ABSTRACT FROM AUTHOR]

This paper studies the current limiting behavior based on an air-core high-temperature superconducting transformer (HTST) and a group of inductor–capacitor series resonant limiters. The air-core HTST is composed of four same double-pancake type high-temperature superconducting coils made up of Bi-2333/Ag tape, and both of primary and secondary windings include two series superconducting coils. It plays the roles of inductive fault current limiting and transformation impedance; in addition, the magnetic flux saturation can also be avoided. Meanwhile, the inductor and capacitor series with the secondary winding of the air-core HTST in series resonance state are the conventional devices. The influence of them on the circuit can almost be ignored, because they are in series resonant state in normal operation. While the fault current appeared in the primary circuit, it will be limited by the impedance of the air-core HTST and the inductor without quench (the inductor and capacitor would quit the series resonant state). According to the preliminary experiment carried out in our laboratory, this superconducting current limiting module can operate as expected, and its behavior is satisfactory. [ABSTRACT FROM AUTHOR]

For the future applications of high-temperature superconducting (HTS) cables in the smart grid with power line communication (PLC), it would be unavoidable for HTS cables to experience the PLC signals. For the normal cables experiencing PLC signals, line trap is a commonly used inserted device to block signals from radiating across other cables. With HTS cables working at low temperature, superconducting line trap (SLT) based on HTS coil and HTS electrode capacitor might play a role to achieve a desired transmission path of PLC signals across HTS cables. Since there still remains a research gap of SLT, a prototype is proposed in this paper and its characteristics are presented by principle analysis as well as experimental research. It is found that SLT can offer a higher blocking impedance to carrier signals and produce much smaller loss at power frequency than the line trap made from normal materials. [ABSTRACT FROM AUTHOR]

A capacitor made of high-temperature superconducting (HTS) electrode plates and a dielectric layer, or “HTS capacitor” for short, has the potential advantages of working with other HTS devices at 77 K and producing low conductive loss at high frequency. It may have a specific application to cryogenic systems at high frequency, such as superconducting wireless power transfer (SWPT) systems. Working with HTS resonant coil in an adiabatic container, the HTS capacitor can also reduce the heat leakage of the cooling system. Considering a lack of relevant experimental study at present, an HTS capacitor composed of YBCO (YBa2Cu3O7- $_x$) tapes and a polyimide layer is proposed in this paper and tested in an SWPT system. Its characteristics and influences on the SWPT system are presented in detail by theoretic analysis and experimental investigation. A comparative experiment is carried out between the fabricated HTS capacitor and other capacitors made from normal materials. Finally, it is confirmed experimentally that the HTS capacitor can have a high-quality factor, work with the HTS resonant coil normally at 77 K, and provide the SWPT system with a performance enhancement. [ABSTRACT FROM AUTHOR]

Based on the theory of time reversal technique and through the use of temporal dispersive delay lines, this paper presents a demonstration of temporal cloaked signal transmission at microwave frequencies. When compared with a conventional signal processing system, the related dispersive delay lines are not required to provide linear group delay response. Thus the proposal simplifies the system structure for temporal cloaking, avoids the drawbacks of easy detection, easy decoding and easy analysed brought by linear modulation system, and then strengthen the safety and reliability in signal transmission. Theoretical analysis and experimental results validate the proposed system. The proposed method and achieved results indicate potential application in secure communications and data multiplexing subject to channel bandwidth requirements. [ABSTRACT FROM AUTHOR]

This paper presents a novel three-coil reconnection electromagnetic launcher (TCREL). Analytical calculations and simulation results indicated that not only does this model possess a higher structural strength, but also the launching efficiency is improved effectively compared with that of the traditional reconnection electromagnetic launcher (REL). In addition, take the TCREL model as an independent module; a toroidal REL (TREL) model can be obtained after several modules are uniformly placed and fixed around the circumference. The TREL model can reduce the magnetic flux leakage among driving coils, and further improves the launching efficiency. To verify the conceptual feasibility, two-stage TCREL and REL models were built and tested. The experiments demonstrate that the TCREL model possesses better launching performance than does the REL model; the former can obtain the desired launching efficiency of 15.818% but the latter only 8.248% in the contrast experiment. The experimental results are also in accordance with the simulation results. [ABSTRACT FROM AUTHOR]

Inductive pulsed power supply (IPPS), especially superconducting pulsed power supply (PS), has been the focus of research in recent years due to its high energy density and low power requirement for the input PS. Quite a lot of fantastic work regarding two or multiple IPPS modules has been presented. But they disregard the mutual inductance between modules. This paper establishes a double-module IPPS based on two high-temperature superconducting pulsed power transformers and takes the mutual inductance between modules into consideration. The influence of the mutual inductance between two modules on three discharge modes of the system is researched. Simulations and experiments on synchronous discharge, time-delay discharge, and asynchronous discharge are carried out, respectively. The results demonstrate that taking the mutual inductance into consideration, the amplitude and the pulsewidth of the output currents are both improved a lot, especially the obtainable energy of load is improved by nearly half. For time-delay discharge, the mutual inductance makes the delay time slightly increase. However, for asynchronous discharge, the mutual inductance increases the positive maximum value of the primary current of the second module. It may exceed the critical current and lead to quench. Consequently, the mutual inductance between modules has positive impacts on synchronous discharge and time-delay discharge of the IPPS system while it brings both advantages and disadvantages to asynchronous discharge. [ABSTRACT FROM AUTHOR]

In this paper, a new structure of coilgun with stepped coil winding was designed. The performance of this structure was investigated and compared to the conventional coilgun with uniform diameter stator coil (UDSC) winding. It can be seen from the results that the trigger position of this new structure moves forward with respect to the conventional coilgun. In order to compare the results, the inductance of the two coils is set to the same. If the initial voltage of the capacitor is lower, as the armature at the optimum trigger position, the muzzle velocity of armature in the conventional UDSC coilgun is relatively larger. Conversely, if the initial voltage of the capacitor is higher, the muzzle velocity of armature in the new structure coilgun is relatively larger. According to the simulation results with the increase of voltage, the difference is more and more obvious. Through the single-stage preliminary experiment in our laboratory, the results were in good agreement with the simulation results. And the trigger position is more forward, so the interaction time between the armature and the coil will be longer. Besides, the coil with stepped structure will increase the efficiency of the coilgun when the voltage level is higher. [ABSTRACT FROM AUTHOR]

A circularly polarized (CP) patch antenna with a new chiral metamaterial structure was proposed. The proposed CP antenna is composed of a conventional linearly polarized patch antenna and a chiral metamaterial (CMM) board. For the CMM unit cell, the geometric parameters of the two pieces of copper films that are patterned on opposite sides of an FR-4 board are quite different. The function that a linear-polarization wave is converted into a circular polarization wave can be realized by the designed structure through simulation verification. When the CMM board is placed in the front of a conventional linear-polarized patch antenna, the antenna polarization mode can be changed to the circular polarized mode. The antenna performances have been investigated numerically and experimentally. Meanwhile, the new CMM structure could be applied to the field of circular-polarized antenna. [ABSTRACT FROM AUTHOR]

Inductive pulsed power supply (IPPS) based on multiple high-temperature superconducting pulsed power transformer (HTSPPT) modules is a novel technology for electromagnetic launching. In a compact multimodule IPPS, the mutual couplings between HTSPPT modules are unavoidable. In this paper, an IPPS with the method of improved pulse-forming process which proved to be feasible by preliminary experiment is proposed to analyze the effect of the mutual couplings. The characteristics of the mutual coupling effect on the IPPS are presented in detail by theoretical analysis and parametric simulations. The evaluation indices reflecting performances of the IPPS under the mutual coupling effect are derived from simulations, including the energy storage capacity, flux linkage, axial tensile force, output current amplitude, and so on. Parametric simulations are executed with respect to the module arrangement, the number of modules, and the arrangement radius. Finally, the analysis of mutual coupling effect is summarized, and a strategy for exploiting mutual couplings between modules is put forward to improve IPPS performance. [ABSTRACT FROM PUBLISHER]

Multipole field electromagnetic launcher (MFEL) is a new type of coilgun that can produce larger radial magnetic field compared to the axial magnetic field, the axial acceleration force of coilgun mainly come from radial magnetic field. Because of the similarity of the magnetic fields between inner and outer regions of MFEL, this paper proposed a double-armature MFEL. One armature coaxial with the drive coil placed inside of MFEL; the other armature coaxial with the drive coil placed outside of MFEL. A single-stage double-armature MFEL was studied by simulation and experimental methods. The simulation results indicated that the muzzle velocity of the double-armature launch is similar to that of the single-armature launch, and the efficiency of double-armature MFEL is obviously larger than that of single armature. To verify the conceptual feasibility, a small-size single-stage double-armature capacitor-driven MFEL was built and tested. The inner small armature weighs 63.13 g, the outer big armature weighs 88.38 g. The experimental results on single-armature launch show good consistency with the simulation results, but there is a little gap between the experimental results on double-armature launch and the simulation results. The causes of the existing differences are considered to be mainly from the consistency difference between the six driving coils and the mutual influence between the inner and outer armatures. [ABSTRACT FROM PUBLISHER]

This paper presents a novel single-stage saddle multipole field electromagnetic launching mode for the realization of projectile linear acceleration with gyroscopic stabilization. The hollow cylindrical projectile with three symmetrical vertical slots can change the eddy current and magnetic field density distribution on the projectile surface. When twisted an angle relative to saddle multipole coils along the circumference, the projectile will be linear accelerated with spinning motion under the action of pulse current. In this paper, analytical calculations and simulation methods were used to analysis this mode, the simulation results indicated that the axial acceleration force and circumferential torque acting on the projectile were generated simultaneously, and an optimal initial twisted angle was existed to make the muzzle rotation speed reach peak. To verify the conceptual feasibility, a single-stage saddle sextupole field electromagnetic launcher was built and tested. The experiment demonstrate that the mode is indeed possible to realize the projectile linear acceleration moving with the gyroscopic stabilization, launching performance can be adjusted by changing the initial voltage or twisted angle, and the experimental results are accordant with the simulation results. [ABSTRACT FROM PUBLISHER]

For electromagnetic emission applications that need a very high amplitude and an appropriate pulsewidth, a pulsed power supply based on multiple high-temperature superconducting pulsed power transformer (HTSPPT) modules is verified in this paper. First, the working processes of multiple HTSPPT modules are analyzed and two small experimental HTSPPTs are described in detail. Then, simulation is carried out to show the major pulse characteristics of two different discharge methods. To verify the feasibility of two discharge methods, high-current testing is carried out with the two HTSPPTs. The results show that a higher amplitude of current pulse can be achieved using synchronous parallel discharge and a larger pulsewidth of current pulse can be achieved using asynchronous parallel discharge. [ABSTRACT FROM AUTHOR]

The thrusts of a cylindrical linear synchronous motor with one or more YBCO bulk magnets as the excitation system were measured for the first time and are presented in this paper. The YBCO bulk magnets are cylindrical with a diameter of 30 mm and a height of 18 mm. The armature of the motor is three phase and made of copper wire coils. The inner diameter of the armature is 40 mm. At the temperature of 77 K and a radial gap of 5 mm between the armature and the excitation system, with a charging magnetization current of 40 A for one YBCO bulk magnet and the RMS value current of 10 A for the armature coils, a peak thrust of 27.2 N was measured. Effects of armature current, charging magnetization current, running time, and magnetizers were also studied. When the excitation system had two or three full magnetized YBCO bulk magnets and magnetizers between them, the thrust was nearly two or three times as strong as the thrust of one YBCO bulk magnet under the same conditions. [ABSTRACT FROM PUBLISHER]

Multipole field electromagnetic launcher (MFEL) is a new type of induction launcher that can produce radial magnetic field. This paper proposed different driving coil connection patterns of MFEL and analyzed their performance through experimental and simulation methods. To verify the conceptual feasibility, a small-size single stage capacitor-driven MFEL was built and tested for the first time. Powered by a 100 \muF capacitor bank charged to 3000 V, the launcher is able to accelerate a 50.4 g projectile to a velocity of 13.3 m/s. Characteristics of MFEL including inductance gradient, driving current, eddy current distribution, and magnetic field distribution were analyzed as well. [ABSTRACT FROM PUBLISHER]