We present a nonlinear ytterbium-doped fiber amplifier based on enhanced nonlinear effects that can produce a flat broadband spectrum ranging from 1050–1225 nm with a maximum average output power of 7.8 W at 14 W pum...We present a nonlinear ytterbium-doped fiber amplifier based on enhanced nonlinear effects that can produce a flat broadband spectrum ranging from 1050–1225 nm with a maximum average output power of 7.8 W at 14 W pump power.Its repetition rate is 89 MHz. Using a pair of gratings and two knife edges as a filter, wavelength tunable picosecond pulses of tens to hundreds of milliwatts can be obtained in the broadband spectrum range. The output power, pulse width, and spectrum（center wavelength and linewidth） are adjusted by tuning the distance of the grating pair and/or the knife edges.Fixing the distance between the two gratings at 15 mm and keeping the output spectrum linewidth at approximately 20 nm,the shortest pulse width obtained is less than 1 ps centered at 1080 nm. The longest wavelength of the short pulses is around1200 nm, and its output power and pulse width are 40 m W and 5.79 ps, respectively. The generation of a flat broadband spectrum is also discussed in this paper.展开更多
Based on the dispersion relation of intense laser pulse propagating in gradually ionized plasma, this paper discusses the frequency modulation induced by ionization of an ultra-short intense laser pulse interacting wi...Based on the dispersion relation of intense laser pulse propagating in gradually ionized plasma, this paper discusses the frequency modulation induced by ionization of an ultra-short intense laser pulse interacting with a gas target. The relationship between the frequency modulation and the ionization rate, the plasmas frequency variation, and the polarization of atoms （ions） is analysed. The numerical results indicate that, at high frequency, the polarization of atoms （ions） plays a more important role than plasma frequency variation in modulating the laser frequency, and the laser frequency variation is different at different positions of the laser pulse.展开更多
The third-order correlation function G^((3))(0,T)can be measured by using the method of noncollinear sum-frequency,by which the pulse-width of the ultr-ashort pulse light produced by modelocked laser is deduced to be ...The third-order correlation function G^((3))(0,T)can be measured by using the method of noncollinear sum-frequency,by which the pulse-width of the ultr-ashort pulse light produced by modelocked laser is deduced to be 35ps.This result is the same as that by other standrd method.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
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
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
Polymethyl methacrylate(PMMA)is an optically transparent thermoplastic with favorable processing conditions.In this study,a series of plastic scintillators are prepared via thermal polymerization,and the impact of PMM...Polymethyl methacrylate(PMMA)is an optically transparent thermoplastic with favorable processing conditions.In this study,a series of plastic scintillators are prepared via thermal polymerization,and the impact of PMMA content on their transparency and pulse shape discrimination(PSD)ability is investigated.The fabricated samples,comprising a polystyrene(PS)-PMMA matrix,30.0 wt%2,5-diphenyloxazole(PPO),and 0.2 wt%9,10-diphenylanthracene(DPA),exhibit high transparency with transmissivity ranging from 70.0 to 90.0%(above 415.0 nm)and demonstrate excellent n/γdiscrimination capability.Transparency increased with increasing PMMA content across the entire visible light spectrum.However,the PSD performance gradually deteriorated when the aromatic matrix was replaced with PMMA.The scintillator containing 20.0 wt%PMMA demonstrated the best stability concerning PSD properties and relative light yields.展开更多
Shielding materials are critical for downhole pulsed neutron tool design because they directly influence the accuracy of formation measurements.A well-designed shield configuration ensures that the response of the too...Shielding materials are critical for downhole pulsed neutron tool design because they directly influence the accuracy of formation measurements.A well-designed shield configuration ensures that the response of the tool is maximally representative of the formation without being affected by the tool and borehole environment.This study investigated the effects of boron-containing materials on neutron and gamma detectors based on a newly designed logging-while-drilling tool that is currently undergoing manufacturing.As the boron content increased,the ability to absorb thermal neutrons increased significantly.Through simulation,it was proven that boron carbide(B_(4)C)can be used as an effective boron shielding material for thermal neutrons,and is therefore employed in this work.To shield against thermal neutrons migrating from the mud pipes,the optimal shielding thicknesses for the near-and far-neutron detectors were determined to be 5 and 4 mm.At a porosity of 25 p.u.,near-neutron sensitivity exhibited a 5.6%increase.Furthermore,to shield the capture gamma generated by thermal neutrons once they enter the tool from the mud pipe and formation,internal and external shields for the gamma detector were evaluated.The results show that the internal shield requires a boron content of 75%,whereas the external shield has a thickness of 14.2 mm thickness and a boron content of 25%to minimize the tool effect.展开更多
The kinetic characteristics of plasma-assisted oxidative pyrolysis of ammonia are studied by using the global/fluid models hybrid solution method.Firstly,the stable products of plasma-assisted oxidative pyrolysis of a...The kinetic characteristics of plasma-assisted oxidative pyrolysis of ammonia are studied by using the global/fluid models hybrid solution method.Firstly,the stable products of plasma-assisted oxidative pyrolysis of ammonia are measured.The results show that the consumption of NH_(3)/O_(2)and the production of N_(2)/H_(2)change linearly with the increase of voltage,which indicates the decoupling of nonequilibrium molecular excitation and oxidative pyrolysis of ammonia at low temperatures.Secondly,the detailed reaction kinetics mechanism of ammonia oxidative pyrolysis stimulated by a nanosecond pulse voltage at low pressure and room temperature is established.Based on the reaction path analysis,the simplified mechanism is obtained.The detailed and simplified mechanism simulation results are compared with experimental data to verify the accuracy of the simplified mechanism.Finally,based on the simplified mechanism,the fluid model of ammonia oxidative pyrolysis stimulated by the nanosecond pulse plasma is established to study the pre-sheath/sheath behavior and the resultant consumption and formation of key species.The results show that the generation,development,and propagation of the pre-sheath have a great influence on the formation and consumption of species.The consumption of NH_(3)by the cathode pre-sheath is greater than that by the anode pre-sheath,but the opposite is true for OH and O(1S).However,within the sheath,almost all reactions do not occur.Further,by changing the parameters of nanosecond pulse power supply voltage,it is found that the electron number density,electron current density,and applied peak voltages are not the direct reasons for the structural changes of the sheath and pre-sheath.Furthermore,the discharge interval has little effect on the sheath structure and gas mixture breakdown.The research results of this paper not only help to understand the kinetic promotion of non-equilibrium excitation in the process of oxidative pyrolysis but also help to explore the influence of transport and chemical reaction kinetics on the oxidative pyrolysis of ammonia.展开更多
We investigate theoretically the effects of chirped laser pulses on high-order harmonic generation(HHG)from solids.We find that the harmonic spectra display redshifts for the driving laser pulses with negative chirp a...We investigate theoretically the effects of chirped laser pulses on high-order harmonic generation(HHG)from solids.We find that the harmonic spectra display redshifts for the driving laser pulses with negative chirp and blueshifts for those with positive chirp,which is due to the change in the instantaneous frequency of the driving laser for different chirped pulses.The analysis of crystal-momentum-resolved(k-resolved)HHG reveals that the frequency shifts are equal for the harmonics generated by different crystal momentum channels.The frequency shifts in the cutoff region are larger than those in the plateau region.With the increase of the absolute value of the chirp parameters,the frequency shifts of HHG become more significant,leading to the shifts from odd-to even-order harmonics.We also demonstrate that the frequency shifts of harmonic spectra are related to the duration of the chirped laser field,but are insensitive to the laser intensity and dephasing time.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
Typical application scenarios,such as vehicle to grid(V2G)and frequency regulation,have imposed significant long-life demands on lithium-ion batteries.Herein,we propose an advanced battery life-extension method employ...Typical application scenarios,such as vehicle to grid(V2G)and frequency regulation,have imposed significant long-life demands on lithium-ion batteries.Herein,we propose an advanced battery life-extension method employing bidirectional pulse charging(BPC)strategy.Unlike traditional constant current charging methods,BPC strategy not only achieves comparable charging speeds but also facilitates V2G frequency regulation simultaneously.It significantly enhances battery cycle ampere-hour throughput and demonstrates remarkable life extension capabilities.For this interesting conclusion,adopting model identification and postmortem characterization to reveal the life regulation mechanism of BPC:it mitigates battery capacity loss attributed to loss of lithium-ion inventory(LLI)in graphite anodes by intermittently regulating the overall battery voltage and anode potential using a negative charging current.Then,from the perspective of internal side reaction,the life extension mechanism is further revealed as inhibition of solid electrolyte interphase(SEI)and lithium dendrite growth by regulating voltage with a bidirectional pulse current,and a semi-empirical life degradation model combining SEI and lithium dendrite growth is developed for BPC scenarios health management,the model parameters are identified by genetic algorithm with the life simulation exhibiting an accuracy exceeding 99%.This finding indicates that under typical rate conditions,adaptable BPC strategies can extend the service life of LFP battery by approximately 123%.Consequently,the developed advanced BPC strategy offers innovative perspectives and insights for the development of long-life battery applications in the future.展开更多
The aim of this study was to evaluate the factors influencing the inactivation effect of intense pulsed light(IPL)on Aeromonas salmonicida grown on chicken meat and skin,and to further develop prediction models of ina...The aim of this study was to evaluate the factors influencing the inactivation effect of intense pulsed light(IPL)on Aeromonas salmonicida grown on chicken meat and skin,and to further develop prediction models of inactivation.In this work,chicken meat and skin inoculated with meat-borne A.salmonicida isolates were subjected to IPL treatments under different conditions.The results showed that IPL had obvious bactericidal effect in the chicken skin and thickness groups when the treatment voltage and time were 7 V combined with 5 s.In addition,the lethality curves of A.salmonicida were fitted under IPL conditions of 3.5-7.5 V.The comparison of statistical parameters revealed that the Weibull model could best fit the mortality curves and could accurately predict the mortality dynamic of A.salmonicida grown on chicken skin.And further a secondary model between the scale factor b and the treatment voltage in Weibull model was established using linear equations,which determined that the secondary model could accurately predict the inactivation of A.salmonicida.This study provides a theoretical basis for future prediction models of Aeromonas,and also provides new ideas for sterilization approaches of meat-borne Aeromonas.展开更多
Starting from the extended nonlinear Schrodinger equation in which the self-steepening effect is included, the evolution and the splitting processes of continuous optical wave whose amplitude is perturbed into time re...Starting from the extended nonlinear Schrodinger equation in which the self-steepening effect is included, the evolution and the splitting processes of continuous optical wave whose amplitude is perturbed into time related ultra-short optical pulse trains in an optical fibre are numerically simulated by adopting the split-step Fourier algorithm. The results show that the self-steepening effect can cause the characteristic of the pulse trains to vary with time, which is different from the self-steepening-free case where the generated pulse trains consist of single pulses which are identical in width, intensity, and interval, namely when pulses move a certain distance, they turn into the pulse trains within a certain time range. Moreover, each single pulse may split into several sub-pulses. And as time goes on, the number of the sub-pulses will decrease gradually and the pulse width and the pulse intensity will change too. With the increase of the self-steepening parameter, the distance needed to generate time-dependent pulse trains will shorten. In addition, for a large self-steepening parameter and at the distance where more sub-pulses appear, the corresponding frequency spectra of pulse trains are also wider.展开更多
The photoionization of a hydrogen atom from its ground state with ultra-fast chirped pulses is investigated by numerically solving the time-dependent Schrodinger equation within length,velocity,and Kramers-Henneberger...The photoionization of a hydrogen atom from its ground state with ultra-fast chirped pulses is investigated by numerically solving the time-dependent Schrodinger equation within length,velocity,and Kramers-Henneberger gauges.Converged results for all gauges for chirp-free pulses agree with the prediction of dynamic interference for ground state hydrogen atoms predicted recently by Jiang and Burgdorfer[Opt.Express 26,19921(2018)].In addition,we investigated photoelectron spectra of hydrogen atoms by chirped laser pulses,and showed that dynamic interference effect will be weaken for pulses with increasing linear chirp.Our numerical results can be understood and discussed in terms of an interplay of photoelectron wavepackets from first and second halves of laser enevelop,including the ac Stark energy level shift of the photoelectron final state and atomic stabilization effect at ultra-high intensities.展开更多
The influence of the ultra-short pulse wavelength on the populations in the three electronic states of CsI molecule is investigated using the time-dependent wave packet method. The calculated results show that the pop...The influence of the ultra-short pulse wavelength on the populations in the three electronic states of CsI molecule is investigated using the time-dependent wave packet method. The calculated results show that the populations in the two excited states approach to the maxima at the wavelengths of 369 nm and 297 nm, respectively. The photodissociation reaction channels of the CsI molecule can be chosen by controlling the pump pulse wavelength.展开更多
Relativistic femtosecond mid-infrared pulses can be generated efficiently by laser interaction with near-criticaldensity plasmas.It is found theoretically and numerically that the radiation pressure of a circularly po...Relativistic femtosecond mid-infrared pulses can be generated efficiently by laser interaction with near-criticaldensity plasmas.It is found theoretically and numerically that the radiation pressure of a circularly polarized laser pulse first compresses the plasma electrons to form a dense flying mirror with a relativistic high speed.The pulse reflected by the mirror is red-shifted to the mid-infrared range.Full three-dimensional simulations demonstrate that the central wavelength of the mid-infrared pulse is tunable from 3µm to 14µm,and the laser energy conversion efficiency can reach as high as 13%.With a 0.5–10 PW incident laser pulse,the generated mid-infrared pulse reaches a peak power of 10–180 TW,which is interesting for various applications in ultrafast and high-field sciences.展开更多
A high-power laser ablating solid targets induces giant electromagnetic pulses(EMPs),which are intimately pertinent to laser parameters,such as energy and pulse width.In this study,we reveal the features of EMPs gener...A high-power laser ablating solid targets induces giant electromagnetic pulses(EMPs),which are intimately pertinent to laser parameters,such as energy and pulse width.In this study,we reveal the features of EMPs generated from a picosecond(ps)laser irradiating solid targets at the SG-Ⅱpicosecond petawatt(PSPW)laser facility.The laser energy and pulse,as well as target material and thickness,show determinative effects on the EMPs’amplitude.More intense EMPs are detected behind targets compared to those at the other three positions,and the EMP amplitude decreases from 90.09 kV/m to 17.8 kV/m with the gold target thickness increasing from 10μm to 20μm,which is suppressed when the laser pulse width is enlarged.The results are expected to provide more insight into EMPs produced by ps lasers coupling with targets and lay the foundation for an effective EMP shielding design in high-power laser infrastructures.展开更多
Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers r...Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive.We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations.We find that net dispersion,linear loss,gain and filter shaping can affect the quality of Nyquist pulses significantly.We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium.Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers.展开更多
In this study,a pulsed,high voltage driven hollow-cathode electron beam sources through an optical trigger is designed with characteristics of simple structure,low cost,and easy triggering.To validate the new design,t...In this study,a pulsed,high voltage driven hollow-cathode electron beam sources through an optical trigger is designed with characteristics of simple structure,low cost,and easy triggering.To validate the new design,the characteristics of hollow-cathode discharge and electron beam characterization under pulsed high voltage drive are studied experimentally and discussed by discharge characteristics and analyses of waveform details,respectively.The validation experiments indicate that the pulsed high voltage supply significantly improves the frequency and stability of the discharge,which provides a new solution for the realization of a high-frequency,high-energy electron beam source.The peak current amplitude in the high-energy electron beam increases from 6.2 A to 79.6 A,which indicates the pulsed power mode significantly improves the electron beam performance.Besides,increasing the capacitance significantly affects the highcurrent,lower-energy electron beam more than the high-energy electron beam.展开更多
基金supported by the National Basic Research Program of China(Grant No.2013CB922404)the National Scientific Research Project of China(Grant No.61177047)the National Natural Science Foundation of China(Grant No.61575011)
文摘We present a nonlinear ytterbium-doped fiber amplifier based on enhanced nonlinear effects that can produce a flat broadband spectrum ranging from 1050–1225 nm with a maximum average output power of 7.8 W at 14 W pump power.Its repetition rate is 89 MHz. Using a pair of gratings and two knife edges as a filter, wavelength tunable picosecond pulses of tens to hundreds of milliwatts can be obtained in the broadband spectrum range. The output power, pulse width, and spectrum（center wavelength and linewidth） are adjusted by tuning the distance of the grating pair and/or the knife edges.Fixing the distance between the two gratings at 15 mm and keeping the output spectrum linewidth at approximately 20 nm,the shortest pulse width obtained is less than 1 ps centered at 1080 nm. The longest wavelength of the short pulses is around1200 nm, and its output power and pulse width are 40 m W and 5.79 ps, respectively. The generation of a flat broadband spectrum is also discussed in this paper.
基金Project supported by the National Science Foundation of China （Grant Nos 10574010 and 10276002） and by Specialized Research Fund for the Doctoral Program of Higher Education （SRFDP） of China （Grant No 20050005016）
文摘Based on the dispersion relation of intense laser pulse propagating in gradually ionized plasma, this paper discusses the frequency modulation induced by ionization of an ultra-short intense laser pulse interacting with a gas target. The relationship between the frequency modulation and the ionization rate, the plasmas frequency variation, and the polarization of atoms （ions） is analysed. The numerical results indicate that, at high frequency, the polarization of atoms （ions） plays a more important role than plasma frequency variation in modulating the laser frequency, and the laser frequency variation is different at different positions of the laser pulse.
文摘The third-order correlation function G^((3))(0,T)can be measured by using the method of noncollinear sum-frequency,by which the pulse-width of the ultr-ashort pulse light produced by modelocked laser is deduced to be 35ps.This result is the same as that by other standrd method.
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 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.
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.
基金supported by the National Natural Science Foundation of China(No.12027813)the fund of National Innovation Center of Radiation Application of China(Nos.KFZC2020020501,KFZC2021010101).
文摘Polymethyl methacrylate(PMMA)is an optically transparent thermoplastic with favorable processing conditions.In this study,a series of plastic scintillators are prepared via thermal polymerization,and the impact of PMMA content on their transparency and pulse shape discrimination(PSD)ability is investigated.The fabricated samples,comprising a polystyrene(PS)-PMMA matrix,30.0 wt%2,5-diphenyloxazole(PPO),and 0.2 wt%9,10-diphenylanthracene(DPA),exhibit high transparency with transmissivity ranging from 70.0 to 90.0%(above 415.0 nm)and demonstrate excellent n/γdiscrimination capability.Transparency increased with increasing PMMA content across the entire visible light spectrum.However,the PSD performance gradually deteriorated when the aromatic matrix was replaced with PMMA.The scintillator containing 20.0 wt%PMMA demonstrated the best stability concerning PSD properties and relative light yields.
基金supported by the Natural Science Foundation of China(Nos.U23B20151 and 52171253).
文摘Shielding materials are critical for downhole pulsed neutron tool design because they directly influence the accuracy of formation measurements.A well-designed shield configuration ensures that the response of the tool is maximally representative of the formation without being affected by the tool and borehole environment.This study investigated the effects of boron-containing materials on neutron and gamma detectors based on a newly designed logging-while-drilling tool that is currently undergoing manufacturing.As the boron content increased,the ability to absorb thermal neutrons increased significantly.Through simulation,it was proven that boron carbide(B_(4)C)can be used as an effective boron shielding material for thermal neutrons,and is therefore employed in this work.To shield against thermal neutrons migrating from the mud pipes,the optimal shielding thicknesses for the near-and far-neutron detectors were determined to be 5 and 4 mm.At a porosity of 25 p.u.,near-neutron sensitivity exhibited a 5.6%increase.Furthermore,to shield the capture gamma generated by thermal neutrons once they enter the tool from the mud pipe and formation,internal and external shields for the gamma detector were evaluated.The results show that the internal shield requires a boron content of 75%,whereas the external shield has a thickness of 14.2 mm thickness and a boron content of 25%to minimize the tool effect.
基金Fundamental Research Funds for the Central Universities(M23JBZY00050)National Natural Science Foundation of China(22278032)。
文摘The kinetic characteristics of plasma-assisted oxidative pyrolysis of ammonia are studied by using the global/fluid models hybrid solution method.Firstly,the stable products of plasma-assisted oxidative pyrolysis of ammonia are measured.The results show that the consumption of NH_(3)/O_(2)and the production of N_(2)/H_(2)change linearly with the increase of voltage,which indicates the decoupling of nonequilibrium molecular excitation and oxidative pyrolysis of ammonia at low temperatures.Secondly,the detailed reaction kinetics mechanism of ammonia oxidative pyrolysis stimulated by a nanosecond pulse voltage at low pressure and room temperature is established.Based on the reaction path analysis,the simplified mechanism is obtained.The detailed and simplified mechanism simulation results are compared with experimental data to verify the accuracy of the simplified mechanism.Finally,based on the simplified mechanism,the fluid model of ammonia oxidative pyrolysis stimulated by the nanosecond pulse plasma is established to study the pre-sheath/sheath behavior and the resultant consumption and formation of key species.The results show that the generation,development,and propagation of the pre-sheath have a great influence on the formation and consumption of species.The consumption of NH_(3)by the cathode pre-sheath is greater than that by the anode pre-sheath,but the opposite is true for OH and O(1S).However,within the sheath,almost all reactions do not occur.Further,by changing the parameters of nanosecond pulse power supply voltage,it is found that the electron number density,electron current density,and applied peak voltages are not the direct reasons for the structural changes of the sheath and pre-sheath.Furthermore,the discharge interval has little effect on the sheath structure and gas mixture breakdown.The research results of this paper not only help to understand the kinetic promotion of non-equilibrium excitation in the process of oxidative pyrolysis but also help to explore the influence of transport and chemical reaction kinetics on the oxidative pyrolysis of ammonia.
基金Project supported by the Natural Science Foundation of Jilin Province of China(Grant No.20230101014JC)the National Natural Science Foundation of China(Grant No.12374265)。
文摘We investigate theoretically the effects of chirped laser pulses on high-order harmonic generation(HHG)from solids.We find that the harmonic spectra display redshifts for the driving laser pulses with negative chirp and blueshifts for those with positive chirp,which is due to the change in the instantaneous frequency of the driving laser for different chirped pulses.The analysis of crystal-momentum-resolved(k-resolved)HHG reveals that the frequency shifts are equal for the harmonics generated by different crystal momentum channels.The frequency shifts in the cutoff region are larger than those in the plateau region.With the increase of the absolute value of the chirp parameters,the frequency shifts of HHG become more significant,leading to the shifts from odd-to even-order harmonics.We also demonstrate that the frequency shifts of harmonic spectra are related to the duration of the chirped laser field,but are insensitive to the laser intensity and dephasing time.
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supported by the National Natural Science Foundation of China(52177217)。
文摘Typical application scenarios,such as vehicle to grid(V2G)and frequency regulation,have imposed significant long-life demands on lithium-ion batteries.Herein,we propose an advanced battery life-extension method employing bidirectional pulse charging(BPC)strategy.Unlike traditional constant current charging methods,BPC strategy not only achieves comparable charging speeds but also facilitates V2G frequency regulation simultaneously.It significantly enhances battery cycle ampere-hour throughput and demonstrates remarkable life extension capabilities.For this interesting conclusion,adopting model identification and postmortem characterization to reveal the life regulation mechanism of BPC:it mitigates battery capacity loss attributed to loss of lithium-ion inventory(LLI)in graphite anodes by intermittently regulating the overall battery voltage and anode potential using a negative charging current.Then,from the perspective of internal side reaction,the life extension mechanism is further revealed as inhibition of solid electrolyte interphase(SEI)and lithium dendrite growth by regulating voltage with a bidirectional pulse current,and a semi-empirical life degradation model combining SEI and lithium dendrite growth is developed for BPC scenarios health management,the model parameters are identified by genetic algorithm with the life simulation exhibiting an accuracy exceeding 99%.This finding indicates that under typical rate conditions,adaptable BPC strategies can extend the service life of LFP battery by approximately 123%.Consequently,the developed advanced BPC strategy offers innovative perspectives and insights for the development of long-life battery applications in the future.
基金supported by projects funded by grants from the Natural Science Foundation of Jiangsu Province in China(BK20221515)the National Natural Science Foundation of China(32172266)the Changzhou Science and Technology Support Program(CE20222002)。
文摘The aim of this study was to evaluate the factors influencing the inactivation effect of intense pulsed light(IPL)on Aeromonas salmonicida grown on chicken meat and skin,and to further develop prediction models of inactivation.In this work,chicken meat and skin inoculated with meat-borne A.salmonicida isolates were subjected to IPL treatments under different conditions.The results showed that IPL had obvious bactericidal effect in the chicken skin and thickness groups when the treatment voltage and time were 7 V combined with 5 s.In addition,the lethality curves of A.salmonicida were fitted under IPL conditions of 3.5-7.5 V.The comparison of statistical parameters revealed that the Weibull model could best fit the mortality curves and could accurately predict the mortality dynamic of A.salmonicida grown on chicken skin.And further a secondary model between the scale factor b and the treatment voltage in Weibull model was established using linear equations,which determined that the secondary model could accurately predict the inactivation of A.salmonicida.This study provides a theoretical basis for future prediction models of Aeromonas,and also provides new ideas for sterilization approaches of meat-borne Aeromonas.
基金supported by Key Program of Natural Science Foundation of Educational Commission of Sichuan Province, China (GrantNo 2006A124)the Fundamental Application Research Project of the Department of Science and Technology of Sichuan Province,China (Grant No 05JY029-084)the Foundation of Science and Technology Development of Chengdu University of Information Technology, China (Grant No KYTZ20060604)
文摘Starting from the extended nonlinear Schrodinger equation in which the self-steepening effect is included, the evolution and the splitting processes of continuous optical wave whose amplitude is perturbed into time related ultra-short optical pulse trains in an optical fibre are numerically simulated by adopting the split-step Fourier algorithm. The results show that the self-steepening effect can cause the characteristic of the pulse trains to vary with time, which is different from the self-steepening-free case where the generated pulse trains consist of single pulses which are identical in width, intensity, and interval, namely when pulses move a certain distance, they turn into the pulse trains within a certain time range. Moreover, each single pulse may split into several sub-pulses. And as time goes on, the number of the sub-pulses will decrease gradually and the pulse width and the pulse intensity will change too. With the increase of the self-steepening parameter, the distance needed to generate time-dependent pulse trains will shorten. In addition, for a large self-steepening parameter and at the distance where more sub-pulses appear, the corresponding frequency spectra of pulse trains are also wider.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774131 and 91850114)
文摘The photoionization of a hydrogen atom from its ground state with ultra-fast chirped pulses is investigated by numerically solving the time-dependent Schrodinger equation within length,velocity,and Kramers-Henneberger gauges.Converged results for all gauges for chirp-free pulses agree with the prediction of dynamic interference for ground state hydrogen atoms predicted recently by Jiang and Burgdorfer[Opt.Express 26,19921(2018)].In addition,we investigated photoelectron spectra of hydrogen atoms by chirped laser pulses,and showed that dynamic interference effect will be weaken for pulses with increasing linear chirp.Our numerical results can be understood and discussed in terms of an interplay of photoelectron wavepackets from first and second halves of laser enevelop,including the ac Stark energy level shift of the photoelectron final state and atomic stabilization effect at ultra-high intensities.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10674114 and 10604045)
文摘The influence of the ultra-short pulse wavelength on the populations in the three electronic states of CsI molecule is investigated using the time-dependent wave packet method. The calculated results show that the populations in the two excited states approach to the maxima at the wavelengths of 369 nm and 297 nm, respectively. The photodissociation reaction channels of the CsI molecule can be chosen by controlling the pump pulse wavelength.
基金supported by the National Natural Science Foundation of China(Grant Nos.12375244,12135009,and 12275356)the Hunan Provincial Innovation Foun-dation for Postgraduate(Grant Nos.CX20210062 and CX20230006).
文摘Relativistic femtosecond mid-infrared pulses can be generated efficiently by laser interaction with near-criticaldensity plasmas.It is found theoretically and numerically that the radiation pressure of a circularly polarized laser pulse first compresses the plasma electrons to form a dense flying mirror with a relativistic high speed.The pulse reflected by the mirror is red-shifted to the mid-infrared range.Full three-dimensional simulations demonstrate that the central wavelength of the mid-infrared pulse is tunable from 3µm to 14µm,and the laser energy conversion efficiency can reach as high as 13%.With a 0.5–10 PW incident laser pulse,the generated mid-infrared pulse reaches a peak power of 10–180 TW,which is interesting for various applications in ultrafast and high-field sciences.
基金Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA25020205)the program of Science and Technology on Plasma Physics Laboratory,China Academy of Engineering Physics(Grant No.6142A04220108)。
文摘A high-power laser ablating solid targets induces giant electromagnetic pulses(EMPs),which are intimately pertinent to laser parameters,such as energy and pulse width.In this study,we reveal the features of EMPs generated from a picosecond(ps)laser irradiating solid targets at the SG-Ⅱpicosecond petawatt(PSPW)laser facility.The laser energy and pulse,as well as target material and thickness,show determinative effects on the EMPs’amplitude.More intense EMPs are detected behind targets compared to those at the other three positions,and the EMP amplitude decreases from 90.09 kV/m to 17.8 kV/m with the gold target thickness increasing from 10μm to 20μm,which is suppressed when the laser pulse width is enlarged.The results are expected to provide more insight into EMPs produced by ps lasers coupling with targets and lay the foundation for an effective EMP shielding design in high-power laser infrastructures.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11621404,11561121003,11727812,61775059,12074122,62022033,and 11704123)Shanghai Rising-Star Program,the Sustainedly Supported Foundation by the National Key Laboratory of Science and Technology on Space Microwave(Grant No.HTKT2022KL504008)+1 种基金Shanghai Natural Science Foundation(Grant No.23ZR1419000)the National Key Laboratory Foundation of China(Grant No.6142411196307).
文摘Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive.We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations.We find that net dispersion,linear loss,gain and filter shaping can affect the quality of Nyquist pulses significantly.We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium.Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers.
基金supported by National Natural Science Foundation of China(No.12102099)the National Key R&D Program of China(No.2021YFC2202700)the Outstanding Academic Leader Project of Shanghai(Youth)(No.23XD1421700),respectively。
文摘In this study,a pulsed,high voltage driven hollow-cathode electron beam sources through an optical trigger is designed with characteristics of simple structure,low cost,and easy triggering.To validate the new design,the characteristics of hollow-cathode discharge and electron beam characterization under pulsed high voltage drive are studied experimentally and discussed by discharge characteristics and analyses of waveform details,respectively.The validation experiments indicate that the pulsed high voltage supply significantly improves the frequency and stability of the discharge,which provides a new solution for the realization of a high-frequency,high-energy electron beam source.The peak current amplitude in the high-energy electron beam increases from 6.2 A to 79.6 A,which indicates the pulsed power mode significantly improves the electron beam performance.Besides,increasing the capacitance significantly affects the highcurrent,lower-energy electron beam more than the high-energy electron beam.
