Energy harvesting storage hybrid devices have garnered considerable attention as self-rechargeable power sources for wireless and ubiquitous electronics.Triboelectric nanogenerators(TENGs),a common type of energy harv...Energy harvesting storage hybrid devices have garnered considerable attention as self-rechargeable power sources for wireless and ubiquitous electronics.Triboelectric nanogenerators(TENGs),a common type of energy harvester,generate alternating current-based,irregular short pulses,posing a challenge for storing the generated electrical energy in energy storage systems that typically operate with direct current(DC)-based low-frequency response.In this study,we propose a new strategy that leverages high-frequency response to develop efficient chargeable TENG-supercapacitor(SC)hybrid devices.A highfrequency SC was fabricated using hollow-structured MXene electrode materials,resulting in a twofold increase in the charging efficiency of the hybrid device compared to a control SC made with conventional carbon electrode materials.For a systematic understanding,the electrochemical interplay between the TENGs and SCs was investigated as a function of the frequency characteristics of SCs(f_(SC))and the output pulse duration of TENGs(Δt_(TENG)).Increasing the fSC·Δt_(TENG) enhanced the charging efficiency of the TENG-SC hybrid devices.This study highlights the importance of frequency response design in developing efficient chargeable TENG-SC hybrid devices.展开更多
An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature,a_(sym)/T,in the heavy-ion reactions near the Fermi energy region,based on the modified Fisher Model.Thi...An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature,a_(sym)/T,in the heavy-ion reactions near the Fermi energy region,based on the modified Fisher Model.This method is applied to the primary fragments of antisymmetrized molecular dynamics(AMD)simulations for ^(46)Fe+^(46)Fe,^(40)Ca+^(40)Ca and ^(48)Ca+^(48)Ca at 35 MeV/nucleon,in order to make direct comparison to the results from the K(N,Z)method of Ono et al.In our improved method,the extracted values of a_(sym)/T increase as the size of isotopes increases whereas,in the K(N,Z)method,the results show rather constant behavior.This increase in our result is attributed to the surface contribution of the symmetry energy in finite nuclei.In order to evaluate the surface contribution,the relation a_(sym)/T=[a_(sym)^((V))(1-k_(S/V) A^(-1/3))]/T is applied and k_(S/V)=1.20~1.25 was extracted.This value is smaller than those extracted from the mass table,reflecting the weakened surface contribution at higher temperature regime.Δμ/T,the difference of the neutron-proton chemical potentials relative to the temperature,is also extracted in this method at the same time.The average values of the extractedΔμ/T,Δμ/T show a linear dependence on the proton-neutron a_(sym)metry parameter of the system,δ_(sys),andΔμ/T=(15.1±0.2)δ_(sys)-(0.5±0.1)is obtained.展开更多
The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis(PEMWE)emerging as the preeminent pathway for...The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis(PEMWE)emerging as the preeminent pathway for hydrogen production.Despite remarkable advancements in this field,confronting the sluggish electrochemical kinetics and inherent high-energy consumption arising from deteriorated mass transport within PEMWE systems remains a formidable obstacle.This impediment stems primarily from the hindered protons mass transfer and the untimely hydrogen bubbles detachment.To address these challenges,we harness the inherent variability of electrical energy and introduce an innovative pulsed dynamic water electrolysis system.Compared to constant voltage electrolysis(hydrogen production rate:51.6 m L h^(-1),energy consumption:5.37 kWh Nm-^(3)H_(2)),this strategy(hydrogen production rate:66 m L h^(-1),energy consumption:3.83 kWh Nm-^(3)H_(2))increases the hydrogen production rate by approximately 27%and reduces the energy consumption by about 28%.Furthermore,we demonstrate the practicality of this system by integrating it with an off-grid photovoltaic(PV)system designed for outdoor operation,successfully driving a hydrogen production current of up to 500 mA under an average voltage of approximately 2 V.The combined results of in-situ characterization and finite element analysis reveal the performance enhancement mechanism:pulsed dynamic electrolysis(PDE)dramatically accelerates the enrichment of protons at the electrode/solution interface and facilitates the release of bubbles on the electrode surface.As such,PDE-enhanced PEMWE represents a synergistic advancement,concurrently enhancing both the hydrogen generation reaction and associated transport processes.This promising technology not only redefines the landscape of electrolysis-based hydrogen production but also holds immense potential for broadening its application across a diverse spectrum of electrocatalytic endeavors.展开更多
Capacitor-based pulsed power supply(PPS)is widely used in fields related to electromagnetic launch,plasma,and materials'synthesis,modification and processing.As industrial applications place higher requirements on...Capacitor-based pulsed power supply(PPS)is widely used in fields related to electromagnetic launch,plasma,and materials'synthesis,modification and processing.As industrial applications place higher requirements on compact and portable pulsed power supplies,the National Key Laboratory of Transient Physics(NKLTP)recently developed a pulsed power supply consisting of a set of compact pulse-forming units(PFU),each with a capacitor energy storage of 220 kJ.This integrated PPS comes with a complete system configuration,a miniature compact structure,a high rate of repetition,and high power,with energy storage density exceeding 1.2 MJ/m^(3).This paper describes the device-level design of the unit,the system layout,the control system,the thermal management system,and the experimental results of the pulsed power supply.The experimental results verified the good reliability of the PPS at high repetition rates with each unit module delivering an output current of more than 100 kA.Additionally,flexible current pulse shapes can be formed by setting the charging voltage and the trigger sequence of the PFUs.The pulse forming network(PFN)developed from these PFUs was successfully applied to electromagnetic launch.展开更多
In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not ...In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.展开更多
The paper is an introduction to the front-end pulse acquisition and the back-end pulse biomimetic reproduction system.This system is capable of faithfully replicating the complete pulse waveform collected at the front...The paper is an introduction to the front-end pulse acquisition and the back-end pulse biomimetic reproduction system.This system is capable of faithfully replicating the complete pulse waveform collected at the front end.Traditional Chinese Medicine(TCM)practitioners analyze and diagnose the pulse patterns at the replication end.Meanwhile,the obtained pulse waveforms are analyzed and learnt by a neural network based on key diagnostic points in TCM pulse taking,which enables the determination of the corresponding relationships between different pulse waveforms and various pulse patterns in TCM pulse taking.With the support of clinical samples,an auxiliary diagnostic system for TCM pulse patterns ensures the accuracy of pulse pattern replication.展开更多
A mid-infrared femtosecond pulse laser with a single cycle and high intensity is an ideal driving light source for generating isolated attosecond pulses. Due to current experimental limitations, it is difficult to dir...A mid-infrared femtosecond pulse laser with a single cycle and high intensity is an ideal driving light source for generating isolated attosecond pulses. Due to current experimental limitations, it is difficult to directly achieve this type of laser light source in the laboratory. In this paper, we obtain such an ideal light source by adding a Ti sapphire pulse to the combined pulse laser consisting of two mid-infrared pulses. Specifically, by combining the synthesized pulse consisting of 8 fs/1200 nm/1.62 × 10^(14)W cm^(-2)and 12 fs/1800 nm/2.71 × 10^(14)W cm^(-2)with an additional 8 fs/800 nm/1.26 × 10^(14)W cm^(-2)Ti sapphire pulse, the resulting electric field waveform is very close to that of a 1170 nm femtosecond pulse with an intensity of 1.4 × 10^(15)W cm^(-2), a single-cycle pulse width, and a carrier-envelope phase of 0.25π. Numerical simulations show that both cases produce high-order harmonic emission spectra with broadband supercontinuum spectra, however, the bandwidth of the supercontinuum spectra and the harmonic intensities in the synthesized pulses are significantly better than those in the single1170 nm pulse. After inverse Fourier transform, we obtain 66 as a high-intensity isolated attosecond pulse, whose intensity is five orders of magnitude higher than that of a monochromatic field. Here, the phase differences between three combined pulse lasers have little effect on the numerical simulation results when they vary in the range of 0.3π.展开更多
Pulsed magnet technology is the only way to generate ultra-strong magnetic fields higher than 45 T so far.However,the inherently fast-changing field strength(typically on the order of 1000 T/s)poses significant challe...Pulsed magnet technology is the only way to generate ultra-strong magnetic fields higher than 45 T so far.However,the inherently fast-changing field strength(typically on the order of 1000 T/s)poses significant challenges for spectroscopic measurements which rely on time integration of signals to improve spectral qualities.In this work,we report high-sensitivity spectroscopic measurements under pulsed high magnetic fields employing the long flat-top pulsed magnetic field technique.By means of a multiple-capacitor power supply,we were able to generate pulsed high magnetic fields with controllable flat-top pulse width and field stabilities.By synchronizing spectroscopic measurements with the waveform of the flattop magnetic field,the integration time of each spectrum can be increased by up to 100 times compared with that of the conventional spectroscopic measurements under pulsed magnetic fields,thus enabling high-sensitivity spectroscopic measurements under ultra-strong pulsed magnetic fields.These findings promise an efficient way to significantly improve the performance and extend the application of optical measurements under pulsed high magnetic fields.展开更多
Doping with Ga effectively enhances the crystal quality and optical detection efficiency of zinc oxide(Zn O)single crystals,which has attracted considerable research interest in radiation detection.The application of ...Doping with Ga effectively enhances the crystal quality and optical detection efficiency of zinc oxide(Zn O)single crystals,which has attracted considerable research interest in radiation detection.The application of Zn O:Ga(GZO)in nuclear energy is particularly significant and fascinating at the fundamental level,enabling neutron/gamma discrimination while preserving the response time properties of the single crystal in sub-nanoseconds,maximizing the effective counting rate of the pulsed radiation field.In this study,the single-particle waveform discrimination characteristics of GZO were evaluated for five charged particles(α,β,H^(+),Li^(+),and O^(8+)and two prevalent uncharged particles(neutrons and gamma rays).Based on the timecorrelation single-photon counting(TCSPC)method,the luminescence decay time constants of the charged particles in the GZO crystal were determined as follows:1.21 ns for H^(+),1.50 ns for Li^(+),1.70 ns for O^(8+),1.56 ns forαparticles,and 1.09 ns forβparticles.Visible differences in the excitation time spectra curves were observed.Using the conventional time-domain or frequency-domain waveform discrimination techniques,waveform discrimination of 14.9 Me V neutrons and secondary gamma rays generated by the CPNG-6 device based on GZO scintillation was successfully implemented.The neutron signal constituted 77.93%of the total,indicating that GZO exhibited superior neutron/gamma discrimination sensitivity compared with that of a commercial stilbene crystal.Using the neutron/gamma screening outcomes,we reconstructed the voltage pulse height,charge height,and neutron multiplication time spectra of the pulsed neutron radiation field.The reconstructed neutron multiplication time spectrum exhibited a deviation of less than 3%relative to the result obtained using a commercial stilbene scintillator.This is the first report in the open literature on the neutron/gamma discrimination and reconstruction of Zn O pulsed radiation-field information.展开更多
As a critical component of pulse solid rocket motors(SRMs),the soft pulse separation device(PSD)is vital in enabling multi-pulse propulsion and has become a breakthrough in SRM engineering applications.To investigate ...As a critical component of pulse solid rocket motors(SRMs),the soft pulse separation device(PSD)is vital in enabling multi-pulse propulsion and has become a breakthrough in SRM engineering applications.To investigate the opening performance of the PSD,an axial PSD incorporating a star-shaped prefabricated defect was designed.The opening process was simulated using peridynamics,yielding the strain field distribution and the corresponding failure mode.A single-opening verification test was conducted.The simulation results showed good agreement with the experimental data,demonstrating the reliability of the peridynamic modeling approach.Furthermore,the effects of the prefabricated defect shape and depth on the opening performance of the PSD were analyzed through simulation.The research results indicate that the established constitutive model and failure criteria based on peridynamics can reasonably predict the failure location and the opening pressure of the soft PSD.Under the impact loading,the weak zone of the soft PSD firstly ruptures,and the damaged area gradually propagates along with the prefabricated defect,eventually leading to complete separation.A smaller prefabricated defect depth or a wider prefabricated defect distribution can cause a reduction in opening pressure.These research results provide valuable guidance for the preliminary design and optimization of PSDs in pulse solid rocket motors.展开更多
This study examines the high-order harmonic radiation behavior of MgO crystals driven by combined pulses based on the numerical solution of the semiconductor Bloch equation.We found that compared with the monochromati...This study examines the high-order harmonic radiation behavior of MgO crystals driven by combined pulses based on the numerical solution of the semiconductor Bloch equation.We found that compared with the monochromatic pulse,the MgO crystal can radiate a continuous harmonic spectrum with two platforms driven by the three-color combined pulse.The reason is that under the three-color combined pulse,the electron ionization and recombination can be effectively controlled within a half-optical cycle of the laser pulse.Using this continuous spectrum,we synthesized an isolated attosecond pulse with a duration of approximately 370 as.This study provides a new perspective on all-solid-state compact optical devices.展开更多
We demonstrated a new type of MAX phase material,chromium titanium aluminum carbide(Cr_(2)TiAlC_(2)) polymer film,to generate a passively Q-switched erbium-doped fiber laser(EDFL).The film thickness was measured to be...We demonstrated a new type of MAX phase material,chromium titanium aluminum carbide(Cr_(2)TiAlC_(2)) polymer film,to generate a passively Q-switched erbium-doped fiber laser(EDFL).The film thickness was measured to be around 45 μm,which was fabricated using the embedding method with polyvinyl alcohol(PVA) polymer as hoster.The saturable absorber(SA) film demonstrates a dual-wavelength passively Q-switched EDFL which operates at 1 531 nm and 1 560.19 nm,respectively.The Q-switching pulse duration could be varied from 2.46 μs to 770 ns,while the repetition rate varied from 92.76 kHz to 106.6 kHz with an increasing input pumping range from 154 mW to 300 mW.The maximum output power and pulse energy of 15.05 mW and 141.18 nJ were obtained at the maximum input power of 300 mW,respectively.展开更多
Cameroon’s capital Yaoundécame alive on 16 and 17 July as it hosted a major international gathering for the liquefied natural gas(LNG)sector.The event brought together over 1,000 industry professionals and 50 ex...Cameroon’s capital Yaoundécame alive on 16 and 17 July as it hosted a major international gathering for the liquefied natural gas(LNG)sector.The event brought together over 1,000 industry professionals and 50 exhibitors from more than 30 countries including China to address the future of cleaner and more inclusive energy.展开更多
As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster(PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at ...As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster(PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at 2 J or more of discharge energy. In this work, the performance of a PPT with a side-fed, tongue-flared electrode configuration operated within a lower discharge energy range of 0.5-2.5 J has been investigated. Ablation and charring of the polytetrafluoroethylene propellant surface were analyzed through field-effect scanning electron microscopy imaging and energy-dispersive X-ray spectroscopy. When the discharge energy fell below 2 J, inconsistencies occurred in the specific impulse and the thrust efficiency due to the measurement of the low mass bit. At energy ≥2 J, the performance parameters are compared with other PPT systems of similar configuration and discussed in depth.展开更多
We propose an all-optical,single-laser-pulse scheme for generating a dense relativistic strongly magnetized electron-positron pair plasma.The scheme involves the interaction of an extremely intense(I■10^(24) W/cm^(2)...We propose an all-optical,single-laser-pulse scheme for generating a dense relativistic strongly magnetized electron-positron pair plasma.The scheme involves the interaction of an extremely intense(I■10^(24) W/cm^(2))circularly polarized laser pulse with a solid-density target containing a conical cavity.Through full-scale three-dimensional particle-in-cell simulations that account for quantum electrodynamic effects,it is shown that this interaction results in two significant outcomes:first,the generation of quasi-static magnetic fields reaching tens of gigagauss,and,second,the production of large quantities of electron-positron pairs(up to 10^(13))via the Breit-Wheeler process.The e^(-)e^(+)plasma becomes trapped in the magnetic field and remains confined in a small volume for hundreds of femtoseconds,far exceeding the laser timescale.The dependence of pair plasma parameters,as well as the efficiency of plasma production and confinement,is discussed in relation to the properties of the laser pulse and the target.Realizing this scheme experimentally would enable the investigation of physical processes relevant to extreme astrophysical environments.展开更多
High-power laser pulses interacting with targets can generate intense electromagnetic pulses(EMPs),which can disrupt physical experimental diagnostics and even damage diagnostic equipment,posing a threat to the reliab...High-power laser pulses interacting with targets can generate intense electromagnetic pulses(EMPs),which can disrupt physical experimental diagnostics and even damage diagnostic equipment,posing a threat to the reliable operation of experiments.In this study,EMPs resulting from multi-petawatt laser irradiating nitrogen gas jets were systematically analyzed and investigated.The experimental results revealed that the EMP amplitude is positively correlated with the quantity and energy of the electrons captured and accelerated by the plasma channel.These factors are reflected by parameters such as laser energy and nitrogen gas jet pressure.Additionally,we propose several potential sources of EMPs produced by laser-irradiated gas jets and separately analyzed their spatiotemporal distributions.The findings provide insight into the mechanisms of EMP generation and introduce a new approach to achieve controllable EMPs by regulating the laser energy and gas jet pressure.展开更多
Conversion between different types of entangled states is an interesting problem in quantum mechanics.But research on the conversion between the Greenberger-Horne-Zeilinger(GHZ)state and Knill-Laflamme-Milburn(KLM)sta...Conversion between different types of entangled states is an interesting problem in quantum mechanics.But research on the conversion between the Greenberger-Horne-Zeilinger(GHZ)state and Knill-Laflamme-Milburn(KLM)state in an atomic system has not been reported.In this paper,we propose a scheme to realize the interconversion(one-step)between the GHZ state and KLM state with Rydberg atoms.By utilizing Rydberg-mediated interactions,we simplify the system.By combining a Lie-transform-based pulse design,the evolution path is built up to realize interconversion of the GHZ state and KLM state.The numerical simulation result shows that the present scheme is robust against decoherence and operational imperfection.展开更多
In semiconductor quantum dot systems,pulse distortion is a significant source of coherent errors,which impedes qubit characterization and control.Here,we demonstrate two calibration methods using a two-qubit system as...In semiconductor quantum dot systems,pulse distortion is a significant source of coherent errors,which impedes qubit characterization and control.Here,we demonstrate two calibration methods using a two-qubit system as the detector to correct distortion and calibrate the transfer function of the control line.Both methods are straightforward to implement,robust against noise,and applicable to a wide range of qubit types.The two methods differ in correction accuracy and complexity.The first,coarse predistortion(CPD)method,partially mitigates distortion.The second,all predistortion(APD)method,measures the transfer function and significantly enhances exchange oscillation uniformity.Both methods use exchange oscillation homogeneity as the metric and are suitable for any qubit driven by a diabatic pulse.We believe these methods will enhance qubit characterization accuracy and operation quality in future applications.展开更多
基金supported by the Basic Science Research Program(RS-2024-00344021 and RS-2023-00261543)through the National Research Foundation of Korea(NRF)grant by the Korean Government(MSIT)the National Research Council of Science&Technology(NST)grant by the Korea Government(MSIT)(GTL24011-000)Korea Institute for Advancement of Technology(KIAT)grant funded by the Korea Government(MOTIE)(RS-2024-00420590,HRD Program for Industrial Innovation).
文摘Energy harvesting storage hybrid devices have garnered considerable attention as self-rechargeable power sources for wireless and ubiquitous electronics.Triboelectric nanogenerators(TENGs),a common type of energy harvester,generate alternating current-based,irregular short pulses,posing a challenge for storing the generated electrical energy in energy storage systems that typically operate with direct current(DC)-based low-frequency response.In this study,we propose a new strategy that leverages high-frequency response to develop efficient chargeable TENG-supercapacitor(SC)hybrid devices.A highfrequency SC was fabricated using hollow-structured MXene electrode materials,resulting in a twofold increase in the charging efficiency of the hybrid device compared to a control SC made with conventional carbon electrode materials.For a systematic understanding,the electrochemical interplay between the TENGs and SCs was investigated as a function of the frequency characteristics of SCs(f_(SC))and the output pulse duration of TENGs(Δt_(TENG)).Increasing the fSC·Δt_(TENG) enhanced the charging efficiency of the TENG-SC hybrid devices.This study highlights the importance of frequency response design in developing efficient chargeable TENG-SC hybrid devices.
文摘An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature,a_(sym)/T,in the heavy-ion reactions near the Fermi energy region,based on the modified Fisher Model.This method is applied to the primary fragments of antisymmetrized molecular dynamics(AMD)simulations for ^(46)Fe+^(46)Fe,^(40)Ca+^(40)Ca and ^(48)Ca+^(48)Ca at 35 MeV/nucleon,in order to make direct comparison to the results from the K(N,Z)method of Ono et al.In our improved method,the extracted values of a_(sym)/T increase as the size of isotopes increases whereas,in the K(N,Z)method,the results show rather constant behavior.This increase in our result is attributed to the surface contribution of the symmetry energy in finite nuclei.In order to evaluate the surface contribution,the relation a_(sym)/T=[a_(sym)^((V))(1-k_(S/V) A^(-1/3))]/T is applied and k_(S/V)=1.20~1.25 was extracted.This value is smaller than those extracted from the mass table,reflecting the weakened surface contribution at higher temperature regime.Δμ/T,the difference of the neutron-proton chemical potentials relative to the temperature,is also extracted in this method at the same time.The average values of the extractedΔμ/T,Δμ/T show a linear dependence on the proton-neutron a_(sym)metry parameter of the system,δ_(sys),andΔμ/T=(15.1±0.2)δ_(sys)-(0.5±0.1)is obtained.
基金National Natural Science Foundation of China(No.52476192,No.52106237)Natural Science Foundation of Heilongjiang Province(No.YQ2022E027)。
文摘The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis(PEMWE)emerging as the preeminent pathway for hydrogen production.Despite remarkable advancements in this field,confronting the sluggish electrochemical kinetics and inherent high-energy consumption arising from deteriorated mass transport within PEMWE systems remains a formidable obstacle.This impediment stems primarily from the hindered protons mass transfer and the untimely hydrogen bubbles detachment.To address these challenges,we harness the inherent variability of electrical energy and introduce an innovative pulsed dynamic water electrolysis system.Compared to constant voltage electrolysis(hydrogen production rate:51.6 m L h^(-1),energy consumption:5.37 kWh Nm-^(3)H_(2)),this strategy(hydrogen production rate:66 m L h^(-1),energy consumption:3.83 kWh Nm-^(3)H_(2))increases the hydrogen production rate by approximately 27%and reduces the energy consumption by about 28%.Furthermore,we demonstrate the practicality of this system by integrating it with an off-grid photovoltaic(PV)system designed for outdoor operation,successfully driving a hydrogen production current of up to 500 mA under an average voltage of approximately 2 V.The combined results of in-situ characterization and finite element analysis reveal the performance enhancement mechanism:pulsed dynamic electrolysis(PDE)dramatically accelerates the enrichment of protons at the electrode/solution interface and facilitates the release of bubbles on the electrode surface.As such,PDE-enhanced PEMWE represents a synergistic advancement,concurrently enhancing both the hydrogen generation reaction and associated transport processes.This promising technology not only redefines the landscape of electrolysis-based hydrogen production but also holds immense potential for broadening its application across a diverse spectrum of electrocatalytic endeavors.
基金financial support from the National Key Laboratory of Transient Physics,Nanjing University of Science and Technology(Grant No.6142604230101)Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant Nos.KYCX20_0321 and KYCX20_0322).
文摘Capacitor-based pulsed power supply(PPS)is widely used in fields related to electromagnetic launch,plasma,and materials'synthesis,modification and processing.As industrial applications place higher requirements on compact and portable pulsed power supplies,the National Key Laboratory of Transient Physics(NKLTP)recently developed a pulsed power supply consisting of a set of compact pulse-forming units(PFU),each with a capacitor energy storage of 220 kJ.This integrated PPS comes with a complete system configuration,a miniature compact structure,a high rate of repetition,and high power,with energy storage density exceeding 1.2 MJ/m^(3).This paper describes the device-level design of the unit,the system layout,the control system,the thermal management system,and the experimental results of the pulsed power supply.The experimental results verified the good reliability of the PPS at high repetition rates with each unit module delivering an output current of more than 100 kA.Additionally,flexible current pulse shapes can be formed by setting the charging voltage and the trigger sequence of the PFUs.The pulse forming network(PFN)developed from these PFUs was successfully applied to electromagnetic launch.
基金supported by the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515010093)the Shenzhen Fundamental Research Program (Stable Support Plan Program)(Nos.JCYJ20220809170611004, 20231121110828001 and 20231121113641002)the National Taipei University of Technology-Shenzhen University Joint Research Program (No.2024001)。
文摘In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.
基金Key R&D Plan of Liaoning Province(No.202000357-JH13/103):Construction of Liaoning Traditional Chinese Medicine Industry Technology Innovation Research InstituteNational Key Research and Development Plan Special Project(No.2019JH2/10300040)。
文摘The paper is an introduction to the front-end pulse acquisition and the back-end pulse biomimetic reproduction system.This system is capable of faithfully replicating the complete pulse waveform collected at the front end.Traditional Chinese Medicine(TCM)practitioners analyze and diagnose the pulse patterns at the replication end.Meanwhile,the obtained pulse waveforms are analyzed and learnt by a neural network based on key diagnostic points in TCM pulse taking,which enables the determination of the corresponding relationships between different pulse waveforms and various pulse patterns in TCM pulse taking.With the support of clinical samples,an auxiliary diagnostic system for TCM pulse patterns ensures the accuracy of pulse pattern replication.
基金supported by the Natural Science Foundation of Jilin Province under Grant No. 20220101028JC。
文摘A mid-infrared femtosecond pulse laser with a single cycle and high intensity is an ideal driving light source for generating isolated attosecond pulses. Due to current experimental limitations, it is difficult to directly achieve this type of laser light source in the laboratory. In this paper, we obtain such an ideal light source by adding a Ti sapphire pulse to the combined pulse laser consisting of two mid-infrared pulses. Specifically, by combining the synthesized pulse consisting of 8 fs/1200 nm/1.62 × 10^(14)W cm^(-2)and 12 fs/1800 nm/2.71 × 10^(14)W cm^(-2)with an additional 8 fs/800 nm/1.26 × 10^(14)W cm^(-2)Ti sapphire pulse, the resulting electric field waveform is very close to that of a 1170 nm femtosecond pulse with an intensity of 1.4 × 10^(15)W cm^(-2), a single-cycle pulse width, and a carrier-envelope phase of 0.25π. Numerical simulations show that both cases produce high-order harmonic emission spectra with broadband supercontinuum spectra, however, the bandwidth of the supercontinuum spectra and the harmonic intensities in the synthesized pulses are significantly better than those in the single1170 nm pulse. After inverse Fourier transform, we obtain 66 as a high-intensity isolated attosecond pulse, whose intensity is five orders of magnitude higher than that of a monochromatic field. Here, the phase differences between three combined pulse lasers have little effect on the numerical simulation results when they vary in the range of 0.3π.
基金financially supported by the National Key Research and Development Program of China(Grant No.2022YFA1602700)the National Natural Science Foundation of China(Grant No.12274159)。
文摘Pulsed magnet technology is the only way to generate ultra-strong magnetic fields higher than 45 T so far.However,the inherently fast-changing field strength(typically on the order of 1000 T/s)poses significant challenges for spectroscopic measurements which rely on time integration of signals to improve spectral qualities.In this work,we report high-sensitivity spectroscopic measurements under pulsed high magnetic fields employing the long flat-top pulsed magnetic field technique.By means of a multiple-capacitor power supply,we were able to generate pulsed high magnetic fields with controllable flat-top pulse width and field stabilities.By synchronizing spectroscopic measurements with the waveform of the flattop magnetic field,the integration time of each spectrum can be increased by up to 100 times compared with that of the conventional spectroscopic measurements under pulsed magnetic fields,thus enabling high-sensitivity spectroscopic measurements under ultra-strong pulsed magnetic fields.These findings promise an efficient way to significantly improve the performance and extend the application of optical measurements under pulsed high magnetic fields.
基金supported by the National Natural Science Foundation of China(Nos.12205370,62204198,12305205,and 12105230)Young Talents Promotion Program of Shaanxi Provincial Science and Technology Association(No.20220514)。
文摘Doping with Ga effectively enhances the crystal quality and optical detection efficiency of zinc oxide(Zn O)single crystals,which has attracted considerable research interest in radiation detection.The application of Zn O:Ga(GZO)in nuclear energy is particularly significant and fascinating at the fundamental level,enabling neutron/gamma discrimination while preserving the response time properties of the single crystal in sub-nanoseconds,maximizing the effective counting rate of the pulsed radiation field.In this study,the single-particle waveform discrimination characteristics of GZO were evaluated for five charged particles(α,β,H^(+),Li^(+),and O^(8+)and two prevalent uncharged particles(neutrons and gamma rays).Based on the timecorrelation single-photon counting(TCSPC)method,the luminescence decay time constants of the charged particles in the GZO crystal were determined as follows:1.21 ns for H^(+),1.50 ns for Li^(+),1.70 ns for O^(8+),1.56 ns forαparticles,and 1.09 ns forβparticles.Visible differences in the excitation time spectra curves were observed.Using the conventional time-domain or frequency-domain waveform discrimination techniques,waveform discrimination of 14.9 Me V neutrons and secondary gamma rays generated by the CPNG-6 device based on GZO scintillation was successfully implemented.The neutron signal constituted 77.93%of the total,indicating that GZO exhibited superior neutron/gamma discrimination sensitivity compared with that of a commercial stilbene crystal.Using the neutron/gamma screening outcomes,we reconstructed the voltage pulse height,charge height,and neutron multiplication time spectra of the pulsed neutron radiation field.The reconstructed neutron multiplication time spectrum exhibited a deviation of less than 3%relative to the result obtained using a commercial stilbene scintillator.This is the first report in the open literature on the neutron/gamma discrimination and reconstruction of Zn O pulsed radiation-field information.
基金supported by the National Natural Science Foundation of China(No.12202011)the Youth Research fund of Shanghai Academy of Spaceflight Technology(KJW-KT-QNKYJJ-2022-25)China Postdoctoral Science Foundation(Nos.2024T170009,2022M710190).
文摘As a critical component of pulse solid rocket motors(SRMs),the soft pulse separation device(PSD)is vital in enabling multi-pulse propulsion and has become a breakthrough in SRM engineering applications.To investigate the opening performance of the PSD,an axial PSD incorporating a star-shaped prefabricated defect was designed.The opening process was simulated using peridynamics,yielding the strain field distribution and the corresponding failure mode.A single-opening verification test was conducted.The simulation results showed good agreement with the experimental data,demonstrating the reliability of the peridynamic modeling approach.Furthermore,the effects of the prefabricated defect shape and depth on the opening performance of the PSD were analyzed through simulation.The research results indicate that the established constitutive model and failure criteria based on peridynamics can reasonably predict the failure location and the opening pressure of the soft PSD.Under the impact loading,the weak zone of the soft PSD firstly ruptures,and the damaged area gradually propagates along with the prefabricated defect,eventually leading to complete separation.A smaller prefabricated defect depth or a wider prefabricated defect distribution can cause a reduction in opening pressure.These research results provide valuable guidance for the preliminary design and optimization of PSDs in pulse solid rocket motors.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.Y23A040001)the National Natural Science Foundation of China(Grant Nos.12374029,12074145,and 11975012)+4 种基金the National Key Research and Development Program of China(Grant No.2019YFA0307700)the Research Foundation for Basic Research of Jilin ProvinceChina(Grant No.20220101003JC)the National College Students Innovation and Entrepreneurship Training Program(Grant No.202310350062)the Graduate Innovation Fund of Jilin University(Grant No.2024CX041)。
文摘This study examines the high-order harmonic radiation behavior of MgO crystals driven by combined pulses based on the numerical solution of the semiconductor Bloch equation.We found that compared with the monochromatic pulse,the MgO crystal can radiate a continuous harmonic spectrum with two platforms driven by the three-color combined pulse.The reason is that under the three-color combined pulse,the electron ionization and recombination can be effectively controlled within a half-optical cycle of the laser pulse.Using this continuous spectrum,we synthesized an isolated attosecond pulse with a duration of approximately 370 as.This study provides a new perspective on all-solid-state compact optical devices.
文摘We demonstrated a new type of MAX phase material,chromium titanium aluminum carbide(Cr_(2)TiAlC_(2)) polymer film,to generate a passively Q-switched erbium-doped fiber laser(EDFL).The film thickness was measured to be around 45 μm,which was fabricated using the embedding method with polyvinyl alcohol(PVA) polymer as hoster.The saturable absorber(SA) film demonstrates a dual-wavelength passively Q-switched EDFL which operates at 1 531 nm and 1 560.19 nm,respectively.The Q-switching pulse duration could be varied from 2.46 μs to 770 ns,while the repetition rate varied from 92.76 kHz to 106.6 kHz with an increasing input pumping range from 154 mW to 300 mW.The maximum output power and pulse energy of 15.05 mW and 141.18 nJ were obtained at the maximum input power of 300 mW,respectively.
文摘Cameroon’s capital Yaoundécame alive on 16 and 17 July as it hosted a major international gathering for the liquefied natural gas(LNG)sector.The event brought together over 1,000 industry professionals and 50 exhibitors from more than 30 countries including China to address the future of cleaner and more inclusive energy.
基金supported by the Ministry of Science,Technology and Innovation,Malaysia(MOSTI)(No.04-02-12-SF0339)。
文摘As the size of satellites scales down, low-power and compact propulsion systems such as the pulsed plasma thruster(PPT) are needed for stabilizing these miniature satellites in orbit. Most PPT systems are operated at 2 J or more of discharge energy. In this work, the performance of a PPT with a side-fed, tongue-flared electrode configuration operated within a lower discharge energy range of 0.5-2.5 J has been investigated. Ablation and charring of the polytetrafluoroethylene propellant surface were analyzed through field-effect scanning electron microscopy imaging and energy-dispersive X-ray spectroscopy. When the discharge energy fell below 2 J, inconsistencies occurred in the specific impulse and the thrust efficiency due to the measurement of the low mass bit. At energy ≥2 J, the performance parameters are compared with other PPT systems of similar configuration and discussed in depth.
基金supported by BMBF-Project No.05P24PF1DFG Project No.PU 213/6-3.
文摘We propose an all-optical,single-laser-pulse scheme for generating a dense relativistic strongly magnetized electron-positron pair plasma.The scheme involves the interaction of an extremely intense(I■10^(24) W/cm^(2))circularly polarized laser pulse with a solid-density target containing a conical cavity.Through full-scale three-dimensional particle-in-cell simulations that account for quantum electrodynamic effects,it is shown that this interaction results in two significant outcomes:first,the generation of quasi-static magnetic fields reaching tens of gigagauss,and,second,the production of large quantities of electron-positron pairs(up to 10^(13))via the Breit-Wheeler process.The e^(-)e^(+)plasma becomes trapped in the magnetic field and remains confined in a small volume for hundreds of femtoseconds,far exceeding the laser timescale.The dependence of pair plasma parameters,as well as the efficiency of plasma production and confinement,is discussed in relation to the properties of the laser pulse and the target.Realizing this scheme experimentally would enable the investigation of physical processes relevant to extreme astrophysical environments.
基金supported by the National Grand Instrument Project(No.2019YFF01014404)the Natural Science Foundation of China(Nos.12122501,61631001,11921006,U2241281,and 11975037)the Foundation of Science and Technology on Plasma Physics Laboratory(No.6142A04220108)。
文摘High-power laser pulses interacting with targets can generate intense electromagnetic pulses(EMPs),which can disrupt physical experimental diagnostics and even damage diagnostic equipment,posing a threat to the reliable operation of experiments.In this study,EMPs resulting from multi-petawatt laser irradiating nitrogen gas jets were systematically analyzed and investigated.The experimental results revealed that the EMP amplitude is positively correlated with the quantity and energy of the electrons captured and accelerated by the plasma channel.These factors are reflected by parameters such as laser energy and nitrogen gas jet pressure.Additionally,we propose several potential sources of EMPs produced by laser-irradiated gas jets and separately analyzed their spatiotemporal distributions.The findings provide insight into the mechanisms of EMP generation and introduce a new approach to achieve controllable EMPs by regulating the laser energy and gas jet pressure.
基金supported by the Department of Education of Liaoning Province(Grant Nos.LJKZ1015,LJ2020005,LJKZZ20220120)the Natural Science Foundation of Liaoning Province(Grant Nos.2020-BS-234,2021-MS-317,2022-MS-372)the Program of Liaoning Bai Qian Wan Talents Program(Grant No.2021921096)。
文摘Conversion between different types of entangled states is an interesting problem in quantum mechanics.But research on the conversion between the Greenberger-Horne-Zeilinger(GHZ)state and Knill-Laflamme-Milburn(KLM)state in an atomic system has not been reported.In this paper,we propose a scheme to realize the interconversion(one-step)between the GHZ state and KLM state with Rydberg atoms.By utilizing Rydberg-mediated interactions,we simplify the system.By combining a Lie-transform-based pulse design,the evolution path is built up to realize interconversion of the GHZ state and KLM state.The numerical simulation result shows that the present scheme is robust against decoherence and operational imperfection.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074368,92165207,12474490,12034018,and 92265113)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302300)+1 种基金the USTC Tang Scholarshippartially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication。
文摘In semiconductor quantum dot systems,pulse distortion is a significant source of coherent errors,which impedes qubit characterization and control.Here,we demonstrate two calibration methods using a two-qubit system as the detector to correct distortion and calibrate the transfer function of the control line.Both methods are straightforward to implement,robust against noise,and applicable to a wide range of qubit types.The two methods differ in correction accuracy and complexity.The first,coarse predistortion(CPD)method,partially mitigates distortion.The second,all predistortion(APD)method,measures the transfer function and significantly enhances exchange oscillation uniformity.Both methods use exchange oscillation homogeneity as the metric and are suitable for any qubit driven by a diabatic pulse.We believe these methods will enhance qubit characterization accuracy and operation quality in future applications.
