Industrial linear accelerators often contain many bunches when their pulse widths are extended to microseconds.As they typically operate at low electron energies and high currents,the interactions among bunches cannot...Industrial linear accelerators often contain many bunches when their pulse widths are extended to microseconds.As they typically operate at low electron energies and high currents,the interactions among bunches cannot be neglected.In this study,an algorithm is introduced for calculating the space charge force of a train with infinite bunches.By utilizing the ring charge model and the particle-in-cell(PIC)method and combining analytical and numerical methods,the proposed algorithm efficiently calculates the space charge force of infinite bunches,enabling the accurate design of accelerator parameters and a comprehensive understanding of the space charge force.This is a significant improvement on existing simulation software such as ASTRA and PARMELA that can only handle a single bunch or a small number of bunches.The PIC algorithm is validated in long drift space transport by comparing it with existing models,such as the infinite-bunch,ASTRA single-bunch,and PARMELA several-bunch algorithms.The space charge force calculation results for the external acceleration field are also verified.The reliability of the proposed algorithm provides a foundation for the design and optimization of industrial accelerators.展开更多
A theoretical study of the influence of a quasi-electrostatic support on the amplification level of the slow space charge wave(SCW) in the amplification section of a superheterodyne free electron laser(FEL) was carrie...A theoretical study of the influence of a quasi-electrostatic support on the amplification level of the slow space charge wave(SCW) in the amplification section of a superheterodyne free electron laser(FEL) was carried out. One of the ways to significantly increase the saturation level of the slow SCW is maintaining the conditions of a three-wave parametric resonance between the slow, fast SCWs and the resulting pump electric field. This can be done by introducing the quasielectrostatic support in the superheterodyne FEL amplification section. Also, it was found that the generated pump electric field significantly influences the maintenance of parametric resonance conditions. As a result, this increases the saturation level of the slow SCW by 70%. Finally, the quasi-electrostatic support significantly reduces the maximum value of the electrostatic undulator pump field strength, which is necessary to achieve the maximum saturation level of the slow SCW.展开更多
The space charge effect (SCE) of static induction transistor (SIT) that occurs in high current region is systematically studied.The I V equations are deduced and well agree with experimental results.Two kinds of ...The space charge effect (SCE) of static induction transistor (SIT) that occurs in high current region is systematically studied.The I V equations are deduced and well agree with experimental results.Two kinds of barriers are presented in SIT,corresponding to channel voltage barrier control (CVBC) mechanism and space charge limited control (SCLC) mechanism respectively.With the increase of drain voltage,the gradual transferring of operational mechanism from CVBC to SCLC is demonstrated.It points out that CVBC mechanism and its contest relationship with space charge barrier makes the SIT distinctly differentiated from JFET and triode devices,etc.The contest relationship of the two potential barriers also results in three different working regions,which are distinctly marked and analyzed.Furthermore,the extreme importance of grid voltage on SCE is illustrated.展开更多
In electron beam technology, one of the critical focuses of research and development efforts is on improving the measurement of electron beam parameters. The parameters are closely related to the generation, emission,...In electron beam technology, one of the critical focuses of research and development efforts is on improving the measurement of electron beam parameters. The parameters are closely related to the generation, emission, operation environment, and role of the electron beam and the corresponding medium. In this study, a field calculation method is proposed, and the electric field intensity distribution on the electron beam’s cross-section is analyzed. The characteristics of beam diffusion caused by the space charge effect are investigated in simulation, and the obtained data are compared with the experiment. The simulation demonstrated that the cross-sectional electric field distribution is primarily affected by the electron beam current, current density distribution, and electron beam propagation speed.展开更多
All-solid-state lithium batteries(ASSLBs)have advantages of safety and high energy density,and they are expected to become the next generation of energy storage devices.Sulfide-based solid-state electrolytes(SSEs)with...All-solid-state lithium batteries(ASSLBs)have advantages of safety and high energy density,and they are expected to become the next generation of energy storage devices.Sulfide-based solid-state electrolytes(SSEs)with high ionic conduc-tivity and low grain boundary resistance exhibit remarkable practical application.However,the space charge layer(SCL)eff ect and high interfacial resistance caused by a mismatch with the current commercial oxide cathodes restrict the develop-ment of sulfide SSEs and ASSLBs.This review summarizes the research progress on the SCL eff ect of sulfide SSEs and oxide cathodes,including the mechanism and direct evidence from high performance in-situ characterizations,as well as recent progress on the interfacial modification strategies to alleviate the SCL eff ect.This study provides future direction to stabilize the high performance sulfide-based solid electrolyte/oxide cathode interface for state-of-the-art ASSLBs and future all-SSE storage devices.展开更多
We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found ...We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.展开更多
In recent years,haze has posed a serious threat to the global climate change,ecological balance and human health.In this study,the laboratory experiments and field observations were performed and a possible charging m...In recent years,haze has posed a serious threat to the global climate change,ecological balance and human health.In this study,the laboratory experiments and field observations were performed and a possible charging mechanism was proposed to investigate the space charge properties in haze events.The laboratory experiments showed that the charge polarity of primary aerosol is determined by species of combustion fuels while the magnitude is dependent on the combustion completeness.The field observations revealed that the space charge of atmosphere aerosol in haze events differs from that of fair weather and is closely related to PM2.5 concentration when Relative Humidity(RH)<60%,with 1 to 2 orders of magnitude less than the case when RH≥60%.The analysis of equivalent chargeto-mass ratio(ECTM)suggested that in haze events the space charge is governed by primary aerosol emitted by combustion of fossil fuel in a low relative humidity,whereas it is manipulated by the secondary chemical reaction of atmosphere aerosol in a high relative humidity.And we can identify the main pollutants in haze events according to the polarity of atmosphere aerosol and quickly take measures when RH<60%.Accordingly,the dusthaze of RH<80% can be divided into dry-dust-haze when RH<60%and wet-dust-haze when 60%≤RH<80%.Our study firstly elucidated the space charge properties of atmosphere aerosol in haze events and can provide a new perspective for the prevention and control of air pollution.展开更多
We construct a cubically nonlinear theory of plural interactions between harmonics of the growing space charge wave（SCW） during the development of the two-stream instability. It is shown that the SCW with a wide fre...We construct a cubically nonlinear theory of plural interactions between harmonics of the growing space charge wave（SCW） during the development of the two-stream instability. It is shown that the SCW with a wide frequency spectrum is formed when the frequency of the first SCW harmonic is much lower than the critical frequency of the two-stream instability.Such SCW has part of the spectrum in which higher harmonics have higher amplitudes. We analyze the dynamics of the plural harmonic interactions of the growing SCW and define the saturation harmonic levels. We find the mechanisms of forming the multiharmonic SCW for the waves with frequencies lower than the critical frequency and for the waves with frequencies that exceed the critical frequency.展开更多
The space charge accumulation in CdZnTe crystals seriously affects the performance of high-flux pulse detectors.The influence of sub-bandgap illumination on the space charge distribution and device performance in CdZn...The space charge accumulation in CdZnTe crystals seriously affects the performance of high-flux pulse detectors.The influence of sub-bandgap illumination on the space charge distribution and device performance in CdZnTe crystals were studied theoretically by Silvaco TCAD software simulation.The sub-bandgap illumination with a wavelength of 890 nm and intensity of 8×10−8 W/cm2 were used in the simulation to explore the space charge distribution and internal electric field distribution in CdZnTe crystals.The simulation results show that the deep level occupation faction is manipulated by the sub-bandgap illumination,thus space charge concentration can be reduced under the bias voltage of 500 V.A flat electric field distribution is obtained,which significantly improves the charge collection efficiency of the CdZnTe detector.Meanwhile,premised on the high resistivity of CdZnTe crystal,the space charge concentration in the crystal can be further reduced with the wavelength of 850 nm and intensity of 1×10−7 W/cm2 illumination.The electric field distribution is flatter and the carrier collection efficiency of the device can be improved more effectively.展开更多
The existence of space charge may be addressed as one of the reasons that could cause shielding failure of transmission lines. In order to study the effect of space charge on discharge propagation path, a new experime...The existence of space charge may be addressed as one of the reasons that could cause shielding failure of transmission lines. In order to study the effect of space charge on discharge propagation path, a new experimental system, including mainly DC high voltage generator, impulse voltage generator as well as rod-plane electrode, has been established. The space charge was generated around the rod by means of pre-applying DC high voltage, and the air gap dis- charge experiments were conducted with and without pre-applying DC high voltage, respectively. Meanwhile, high speed cameras worked simultaneously from the front and lateral side to record the discharge propagation path so as to obtain the curvature. After statistical analysis, it is shown that the curvature increases in the middle and lower portions of the propagation path when the effect of space charge is taken into account.展开更多
In this paper,we introduce a method of quantitatively evaluating and controlling the space charge effect of a lasercooled three-dimensional（3 D） ion system in a linear Paul trap.The relationship among cooling effici...In this paper,we introduce a method of quantitatively evaluating and controlling the space charge effect of a lasercooled three-dimensional（3 D） ion system in a linear Paul trap.The relationship among cooling efficiency,ion quantity,and trapping strength is analyzed quantitatively,and the dynamic space distribution and temporal evolution of the 3 D ion system on a secular motion period time scale in the cooling process are obtained.The ion number influences the eigen-micromotion feature of the ion system.When trapping parameter q is ～ 0.3,relatively ideal cooling efficiency and equilibrium temperature can be obtained.The decrease of axial electrostatic potential is helpful in reducing the micromotion heating effect and the degradation in the total energy.Within a single secular motion period under different cooling conditions,ions transform from the cloud state（each ion disperses throughout the envelope of the ion system） to the liquid state（each ion is concentrated at a specific location in the ion system） and then to the crystal state（each ion is subjected to a fixed motion track）.These results are conducive to long-term storage and precise control,motion effect suppression,high-efficiency cooling,and increasing the precision of spectroscopy for a 3 D ion system.展开更多
This paper reports that a cloud of laser-cooled ^40Ca^＋ is successfully trapped and manipulated in the home-built linear ion trap constructed for quantum information processing （QIP）. The frequency of the secular m...This paper reports that a cloud of laser-cooled ^40Ca^＋ is successfully trapped and manipulated in the home-built linear ion trap constructed for quantum information processing （QIP）. The frequency of the secular motion and the space charge density of the ion cloud are measured, which help knowing the characteristic of the trapping potential and are the prerequisite of QIP with the trapped ions.展开更多
The "cascade static lens （CSL） gauge" has a high sensitivity（S） because the emitted electrons repeat the go and back oscillation before they are received by the electrodes. (S=18.6 Pa<sup>-1</su...The "cascade static lens （CSL） gauge" has a high sensitivity（S） because the emitted electrons repeat the go and back oscillation before they are received by the electrodes. (S=18.6 Pa<sup>-1</sup> (2480 Torr<sup>-1</sup> in a展开更多
This paper investigates theoretically the behavior of the space charge region of a silicon solar cell and its associated capacitance under the effect of an external electric field. The purpose of this work is to show ...This paper investigates theoretically the behavior of the space charge region of a silicon solar cell and its associated capacitance under the effect of an external electric field. The purpose of this work is to show that under illumination the solar cell’s space charge region width varies with both operating point and the external induced electric field and how the solar cell capacitance varies with the space charge region width. Based on a 1D modelling of the quasi-neutral p-base, the space charge region width is determined and the associated capacitance is calculated taking into account the external electric field and the junction dynamic velocity. Based on the above calculations and simulations conducted with Mathcad, we confirmed the linear dependence of the inverse capacitance with space charge region width for thin space charge region and we exhibit an exponential dependence for large space charge region.展开更多
The ion-selective porous membrane is the key component in osmotic energy conversion,and optimizing its permeability and selectivity is crucial for improving output performance.Here,to construct a permeability and sele...The ion-selective porous membrane is the key component in osmotic energy conversion,and optimizing its permeability and selectivity is crucial for improving output performance.Here,to construct a permeability and selectivity synergistically enhanced osmotic energy generator,the surface and space charge synergistically enhanced 3D composite membrane is prepared by inserting sulfonated hydrogels into the 3D ion channels with tunable surface charge.The membrane's selectivity is improved from 0.66 to 0.94 by increasing the charge density on the membrane surface and the spatial charge density of the membrane.The experimental and simulation results showed that the synergistic enhancement of the spatial and surface charges significantly improved the electrostatic interactions between the ions and the ion channels,which led to the enhancement of selectivity,net ionic fluxes,and output performance.The space charge improved composite membrane presents an advanced power density of about 6.4 W·m^(-2) under a 50-fold concentration gradient,which is nearly 2 times that of the phase inversion membrane without hydrogels.Our study provides a promising solution for constructing high-performance osmotic energy generators.展开更多
To suppress the resistivity positive temperature coefficient(PTC)effect of ethylene-butyl acrylate copolymer(EBA)-based semi-conductive shielding layer and the injection of charge carriers to insulation layer,the pola...To suppress the resistivity positive temperature coefficient(PTC)effect of ethylene-butyl acrylate copolymer(EBA)-based semi-conductive shielding layer and the injection of charge carriers to insulation layer,the polar molecule maleic anhydride(MAH)is grafted onto EBA macromolecules by melt blending and thermal grafting.The resistivity temperature stability of the grafted semi-conductive composites,as well as the space charge distribution and direct current(DC)breakdown characteristics of cross-linked polyethylene(XLPE)insulation using the composites as the electrode is investigated.The results show that MAH grafting can significantly reduce the volume resistivity of semi-conductive composites,especially at a higher temperature,to suppress the PTC effect.And,the grafted semi-conductive composites can prevent the injection of charge carriers to XLPE insulation from the semi-conductive electrode to improve the space charge distribution and DC breakdown strength of XLPE insulation.The polar anhydride groups in the grafted MAH can enhance the interaction between EBA macromolecular chains and between EBA macromolecular chains and carbon black(CB)to improve the dispersion of CB in EBA matrix and the stability of the internal conductive network at the high temperature,improving the properties of EBA-based semi-conductive shielding layer and DC electrical properties of XLPE insulation layer.展开更多
Titanium dioxide(TiO_(2))is an extremely promising anode material for lithium-ion batteries due to its low cost,minimal volume change,and extended cycle life.However,its electrochemical performance is severely hindere...Titanium dioxide(TiO_(2))is an extremely promising anode material for lithium-ion batteries due to its low cost,minimal volume change,and extended cycle life.However,its electrochemical performance is severely hindered by inherent issues such as poor ionic and electronic conductivity.Here,we design a dual-phase conductor Co@TiO_(2),which contributes a synergistic storage mode consisting of a Li-accepting and an electron-accepting phase.In situ magnetic characterization and experimental results reveal the space charge storage mechanism in addition to traditional insertion mechanisms.Based on these mechanisms,the specific capacity and rate performance of the Co@TiO_(2)electrode have been greatly enhanced.Under a current density of 200 mA·g^(-1),the specific capacity of Co@TiO_(2)reaches 397.2 mAh·g^(-1).Upon increasing the current density to 10 A·g^(-1),the electrode still maintains a capacity of 83.1 mAh·g^(-1)after 900 cycles.This result offers a fresh perspective on the structural design of new anode materials to achieve high energy density.展开更多
With the significant development of high-intensity hadron(proton and heavy ion)accelerator facilities,the space charge effect has become a major limiting factor for increasing beam intensity because it can drive parti...With the significant development of high-intensity hadron(proton and heavy ion)accelerator facilities,the space charge effect has become a major limiting factor for increasing beam intensity because it can drive particle resonance,forming beam halos and causing beam quality degradation or even beam loss.In studies on space charge,the particle-core model(PCM)has been widely adopted to describe halo particle formation.In this paper,we generalize the conventional PCM to include dispersion to investigate the physical mechanism of the beam halo in high-intensity synchrotrons.In particular,a“1:1 parametric resonance”driven by the combined effects of space charge and dispersion is identified.A large dispersion is proven to have a damping effect on the 2:1 parametric resonance.The analysis based on the generalized PCM agrees with particle-in-cell simulations.A beam halo with large mismatch oscillations is also discussed.展开更多
As the ultra high DC voltage grid comes into an important stage in the ‘Twelfth Five-year Plan’ of China, the requirement on the operation safety of power equipment needs to be improved. Oil-paper insulation plays a...As the ultra high DC voltage grid comes into an important stage in the ‘Twelfth Five-year Plan’ of China, the requirement on the operation safety of power equipment needs to be improved. Oil-paper insulation plays a significant role as the main insulation material of many key power equipments. The space charge behaviors of oil-paper insulation not only affect the dielectric strength, but also relate to the stability and security of power transmission facilities. Until now, the research on the space charge behaviors of oil-paper insulation remains on the stage of objective description and phenomenon explanation, thus it is very urgent to make some feature extractions on the test results in order to further investigate the DC space charge behaviors of oil-paper insulation. In this paper, based on the large numbers of test data in the first stage, data mining and feature extractions were performed on the DC space charge behavior of oil-paper insulation. The variation laws of some key characteristic parameters obtained in different experiment conditions such as the total charge injection amount, apparent charge mobility, and trap energy distribution were analyzed. In addition, the distribution of trapping level inside oil-paper was calculated by using the PEA test results based on the mechanism of the isothermal decay current, which realized the approximate calculation of trap depth by charge decay characteristics. What’s more, the exponential injection and decay equations of DC space charge changing with time were acquired for the first time, and the physical meanings of related parameters were defined. This has laid a foundation for the prediction and simulation of space charge in the oil-paper insulation.展开更多
The DC electric field is sometimes accompanied by space charges caused by the partial discharge in the air,which impacts DC electric field measurements.This paper describes the impact factors in the calibration and ap...The DC electric field is sometimes accompanied by space charges caused by the partial discharge in the air,which impacts DC electric field measurements.This paper describes the impact factors in the calibration and application of the field mill for measuring the DC electric field with space charges.First,the influence of the space charges on calibration results is evaluated and discussed.Then,both the impact of the height of the meter probe above the ground and the touch resistance between the ground and the meter on the measurement results are investigated.Correct calibration and application methods are presented.The results are expected to be of use to engineers for conducting accurate measurements of the DC electric field with space charges.展开更多
基金supported by the National Key Research and Development Program(No.2022YFC2402300)。
文摘Industrial linear accelerators often contain many bunches when their pulse widths are extended to microseconds.As they typically operate at low electron energies and high currents,the interactions among bunches cannot be neglected.In this study,an algorithm is introduced for calculating the space charge force of a train with infinite bunches.By utilizing the ring charge model and the particle-in-cell(PIC)method and combining analytical and numerical methods,the proposed algorithm efficiently calculates the space charge force of infinite bunches,enabling the accurate design of accelerator parameters and a comprehensive understanding of the space charge force.This is a significant improvement on existing simulation software such as ASTRA and PARMELA that can only handle a single bunch or a small number of bunches.The PIC algorithm is validated in long drift space transport by comparing it with existing models,such as the infinite-bunch,ASTRA single-bunch,and PARMELA several-bunch algorithms.The space charge force calculation results for the external acceleration field are also verified.The reliability of the proposed algorithm provides a foundation for the design and optimization of industrial accelerators.
文摘A theoretical study of the influence of a quasi-electrostatic support on the amplification level of the slow space charge wave(SCW) in the amplification section of a superheterodyne free electron laser(FEL) was carried out. One of the ways to significantly increase the saturation level of the slow SCW is maintaining the conditions of a three-wave parametric resonance between the slow, fast SCWs and the resulting pump electric field. This can be done by introducing the quasielectrostatic support in the superheterodyne FEL amplification section. Also, it was found that the generated pump electric field significantly influences the maintenance of parametric resonance conditions. As a result, this increases the saturation level of the slow SCW by 70%. Finally, the quasi-electrostatic support significantly reduces the maximum value of the electrostatic undulator pump field strength, which is necessary to achieve the maximum saturation level of the slow SCW.
文摘The space charge effect (SCE) of static induction transistor (SIT) that occurs in high current region is systematically studied.The I V equations are deduced and well agree with experimental results.Two kinds of barriers are presented in SIT,corresponding to channel voltage barrier control (CVBC) mechanism and space charge limited control (SCLC) mechanism respectively.With the increase of drain voltage,the gradual transferring of operational mechanism from CVBC to SCLC is demonstrated.It points out that CVBC mechanism and its contest relationship with space charge barrier makes the SIT distinctly differentiated from JFET and triode devices,etc.The contest relationship of the two potential barriers also results in three different working regions,which are distinctly marked and analyzed.Furthermore,the extreme importance of grid voltage on SCE is illustrated.
基金Project supported by CAST Innovation Fund (Grant No.CAST-BISEE2019-040)。
文摘In electron beam technology, one of the critical focuses of research and development efforts is on improving the measurement of electron beam parameters. The parameters are closely related to the generation, emission, operation environment, and role of the electron beam and the corresponding medium. In this study, a field calculation method is proposed, and the electric field intensity distribution on the electron beam’s cross-section is analyzed. The characteristics of beam diffusion caused by the space charge effect are investigated in simulation, and the obtained data are compared with the experiment. The simulation demonstrated that the cross-sectional electric field distribution is primarily affected by the electron beam current, current density distribution, and electron beam propagation speed.
基金financially supported by National Natural Science Foundation of China(Nos.21575015,21203008,21975025,and 51772030)the Beijing Nature Science Foundation(No.2172051),the National Key Research and Develop-ment Program of China(No.2016YFB0100204)+1 种基金Beijing Outstand-ing Young Scientists Program(No.BJJWZYJH01201910007023)funded by State Key Laboratory for Modification of Chemi-cal Fibers and Polymer Materials,Donghua University.
文摘All-solid-state lithium batteries(ASSLBs)have advantages of safety and high energy density,and they are expected to become the next generation of energy storage devices.Sulfide-based solid-state electrolytes(SSEs)with high ionic conduc-tivity and low grain boundary resistance exhibit remarkable practical application.However,the space charge layer(SCL)eff ect and high interfacial resistance caused by a mismatch with the current commercial oxide cathodes restrict the develop-ment of sulfide SSEs and ASSLBs.This review summarizes the research progress on the SCL eff ect of sulfide SSEs and oxide cathodes,including the mechanism and direct evidence from high performance in-situ characterizations,as well as recent progress on the interfacial modification strategies to alleviate the SCL eff ect.This study provides future direction to stabilize the high performance sulfide-based solid electrolyte/oxide cathode interface for state-of-the-art ASSLBs and future all-SSE storage devices.
基金Supported by the Ministry of Education and Science of Ukraine under Grant No 0117U002253
文摘We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.
基金supported by a grant from the National Natural Science Foundation of China(Nos.11490551)
文摘In recent years,haze has posed a serious threat to the global climate change,ecological balance and human health.In this study,the laboratory experiments and field observations were performed and a possible charging mechanism was proposed to investigate the space charge properties in haze events.The laboratory experiments showed that the charge polarity of primary aerosol is determined by species of combustion fuels while the magnitude is dependent on the combustion completeness.The field observations revealed that the space charge of atmosphere aerosol in haze events differs from that of fair weather and is closely related to PM2.5 concentration when Relative Humidity(RH)<60%,with 1 to 2 orders of magnitude less than the case when RH≥60%.The analysis of equivalent chargeto-mass ratio(ECTM)suggested that in haze events the space charge is governed by primary aerosol emitted by combustion of fossil fuel in a low relative humidity,whereas it is manipulated by the secondary chemical reaction of atmosphere aerosol in a high relative humidity.And we can identify the main pollutants in haze events according to the polarity of atmosphere aerosol and quickly take measures when RH<60%.Accordingly,the dusthaze of RH<80% can be divided into dry-dust-haze when RH<60%and wet-dust-haze when 60%≤RH<80%.Our study firstly elucidated the space charge properties of atmosphere aerosol in haze events and can provide a new perspective for the prevention and control of air pollution.
文摘We construct a cubically nonlinear theory of plural interactions between harmonics of the growing space charge wave（SCW） during the development of the two-stream instability. It is shown that the SCW with a wide frequency spectrum is formed when the frequency of the first SCW harmonic is much lower than the critical frequency of the two-stream instability.Such SCW has part of the spectrum in which higher harmonics have higher amplitudes. We analyze the dynamics of the plural harmonic interactions of the growing SCW and define the saturation harmonic levels. We find the mechanisms of forming the multiharmonic SCW for the waves with frequencies lower than the critical frequency and for the waves with frequencies that exceed the critical frequency.
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China(Grant Nos.51702271 and 61904155)the Natural Science Foundation of Fujian Province,China(Grant No.2020J05239).
文摘The space charge accumulation in CdZnTe crystals seriously affects the performance of high-flux pulse detectors.The influence of sub-bandgap illumination on the space charge distribution and device performance in CdZnTe crystals were studied theoretically by Silvaco TCAD software simulation.The sub-bandgap illumination with a wavelength of 890 nm and intensity of 8×10−8 W/cm2 were used in the simulation to explore the space charge distribution and internal electric field distribution in CdZnTe crystals.The simulation results show that the deep level occupation faction is manipulated by the sub-bandgap illumination,thus space charge concentration can be reduced under the bias voltage of 500 V.A flat electric field distribution is obtained,which significantly improves the charge collection efficiency of the CdZnTe detector.Meanwhile,premised on the high resistivity of CdZnTe crystal,the space charge concentration in the crystal can be further reduced with the wavelength of 850 nm and intensity of 1×10−7 W/cm2 illumination.The electric field distribution is flatter and the carrier collection efficiency of the device can be improved more effectively.
文摘The existence of space charge may be addressed as one of the reasons that could cause shielding failure of transmission lines. In order to study the effect of space charge on discharge propagation path, a new experimental system, including mainly DC high voltage generator, impulse voltage generator as well as rod-plane electrode, has been established. The space charge was generated around the rod by means of pre-applying DC high voltage, and the air gap dis- charge experiments were conducted with and without pre-applying DC high voltage, respectively. Meanwhile, high speed cameras worked simultaneously from the front and lateral side to record the discharge propagation path so as to obtain the curvature. After statistical analysis, it is shown that the curvature increases in the middle and lower portions of the propagation path when the effect of space charge is taken into account.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0304401)the National Natural Science Foundation of China(Grant Nos.11622434,11474318,91336211,and 11634013)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21030100)Hubei Province Science Fund for Distinguished Young Scholars(Grant No.2017CFA040)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2015274)
文摘In this paper,we introduce a method of quantitatively evaluating and controlling the space charge effect of a lasercooled three-dimensional（3 D） ion system in a linear Paul trap.The relationship among cooling efficiency,ion quantity,and trapping strength is analyzed quantitatively,and the dynamic space distribution and temporal evolution of the 3 D ion system on a secular motion period time scale in the cooling process are obtained.The ion number influences the eigen-micromotion feature of the ion system.When trapping parameter q is ～ 0.3,relatively ideal cooling efficiency and equilibrium temperature can be obtained.The decrease of axial electrostatic potential is helpful in reducing the micromotion heating effect and the degradation in the total energy.Within a single secular motion period under different cooling conditions,ions transform from the cloud state（each ion disperses throughout the envelope of the ion system） to the liquid state（each ion is concentrated at a specific location in the ion system） and then to the crystal state（each ion is subjected to a fixed motion track）.These results are conducive to long-term storage and precise control,motion effect suppression,high-efficiency cooling,and increasing the precision of spectroscopy for a 3 D ion system.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10774161,10774163 and 10974225)by National Fundamental Research Program of China (Grant No. 2006CB921203)
文摘This paper reports that a cloud of laser-cooled ^40Ca^＋ is successfully trapped and manipulated in the home-built linear ion trap constructed for quantum information processing （QIP）. The frequency of the secular motion and the space charge density of the ion cloud are measured, which help knowing the characteristic of the trapping potential and are the prerequisite of QIP with the trapped ions.
文摘The "cascade static lens （CSL） gauge" has a high sensitivity（S） because the emitted electrons repeat the go and back oscillation before they are received by the electrodes. (S=18.6 Pa<sup>-1</sup> (2480 Torr<sup>-1</sup> in a
文摘This paper investigates theoretically the behavior of the space charge region of a silicon solar cell and its associated capacitance under the effect of an external electric field. The purpose of this work is to show that under illumination the solar cell’s space charge region width varies with both operating point and the external induced electric field and how the solar cell capacitance varies with the space charge region width. Based on a 1D modelling of the quasi-neutral p-base, the space charge region width is determined and the associated capacitance is calculated taking into account the external electric field and the junction dynamic velocity. Based on the above calculations and simulations conducted with Mathcad, we confirmed the linear dependence of the inverse capacitance with space charge region width for thin space charge region and we exhibit an exponential dependence for large space charge region.
基金the National Natural Science Foundation of China(Grant Nos.22373042 and 22341301)Excellent Young Scientific and Technological Talents of Jilin Province Project(20240602013RC)Fundamental Research Funds forthe Central Universities.
文摘The ion-selective porous membrane is the key component in osmotic energy conversion,and optimizing its permeability and selectivity is crucial for improving output performance.Here,to construct a permeability and selectivity synergistically enhanced osmotic energy generator,the surface and space charge synergistically enhanced 3D composite membrane is prepared by inserting sulfonated hydrogels into the 3D ion channels with tunable surface charge.The membrane's selectivity is improved from 0.66 to 0.94 by increasing the charge density on the membrane surface and the spatial charge density of the membrane.The experimental and simulation results showed that the synergistic enhancement of the spatial and surface charges significantly improved the electrostatic interactions between the ions and the ion channels,which led to the enhancement of selectivity,net ionic fluxes,and output performance.The space charge improved composite membrane presents an advanced power density of about 6.4 W·m^(-2) under a 50-fold concentration gradient,which is nearly 2 times that of the phase inversion membrane without hydrogels.Our study provides a promising solution for constructing high-performance osmotic energy generators.
基金National Natural Science Foundation of China,Grant/Award Number:U20A20307Key Laboratory of Engineering Dielectrics and Its Application(Harbin University of Science and Technology),Ministry of Education,Grant/Award Number:KFM202102。
文摘To suppress the resistivity positive temperature coefficient(PTC)effect of ethylene-butyl acrylate copolymer(EBA)-based semi-conductive shielding layer and the injection of charge carriers to insulation layer,the polar molecule maleic anhydride(MAH)is grafted onto EBA macromolecules by melt blending and thermal grafting.The resistivity temperature stability of the grafted semi-conductive composites,as well as the space charge distribution and direct current(DC)breakdown characteristics of cross-linked polyethylene(XLPE)insulation using the composites as the electrode is investigated.The results show that MAH grafting can significantly reduce the volume resistivity of semi-conductive composites,especially at a higher temperature,to suppress the PTC effect.And,the grafted semi-conductive composites can prevent the injection of charge carriers to XLPE insulation from the semi-conductive electrode to improve the space charge distribution and DC breakdown strength of XLPE insulation.The polar anhydride groups in the grafted MAH can enhance the interaction between EBA macromolecular chains and between EBA macromolecular chains and carbon black(CB)to improve the dispersion of CB in EBA matrix and the stability of the internal conductive network at the high temperature,improving the properties of EBA-based semi-conductive shielding layer and DC electrical properties of XLPE insulation layer.
基金financially supported by the National Natural Science Foundation of China(Nos.92372127 and 22179066)Natural Science Foundation of Shandong,China(Nos.ZR2023JQ017,202210060028,and ZR2021QE061)
文摘Titanium dioxide(TiO_(2))is an extremely promising anode material for lithium-ion batteries due to its low cost,minimal volume change,and extended cycle life.However,its electrochemical performance is severely hindered by inherent issues such as poor ionic and electronic conductivity.Here,we design a dual-phase conductor Co@TiO_(2),which contributes a synergistic storage mode consisting of a Li-accepting and an electron-accepting phase.In situ magnetic characterization and experimental results reveal the space charge storage mechanism in addition to traditional insertion mechanisms.Based on these mechanisms,the specific capacity and rate performance of the Co@TiO_(2)electrode have been greatly enhanced.Under a current density of 200 mA·g^(-1),the specific capacity of Co@TiO_(2)reaches 397.2 mAh·g^(-1).Upon increasing the current density to 10 A·g^(-1),the electrode still maintains a capacity of 83.1 mAh·g^(-1)after 900 cycles.This result offers a fresh perspective on the structural design of new anode materials to achieve high energy density.
基金supported by the National Natural Science Foundation of China(No.12475155)the GuangDong Basic and Applied Basic Research Foundation(No.2024A1515012658)the International Partnership Program of Chinese Academy of Sciences(No.013GJHZ2023026FN)。
文摘With the significant development of high-intensity hadron(proton and heavy ion)accelerator facilities,the space charge effect has become a major limiting factor for increasing beam intensity because it can drive particle resonance,forming beam halos and causing beam quality degradation or even beam loss.In studies on space charge,the particle-core model(PCM)has been widely adopted to describe halo particle formation.In this paper,we generalize the conventional PCM to include dispersion to investigate the physical mechanism of the beam halo in high-intensity synchrotrons.In particular,a“1:1 parametric resonance”driven by the combined effects of space charge and dispersion is identified.A large dispersion is proven to have a damping effect on the 2:1 parametric resonance.The analysis based on the generalized PCM agrees with particle-in-cell simulations.A beam halo with large mismatch oscillations is also discussed.
基金supported by the National Basic Research Program of China ("973" Program) (Grant No. 2009CB724505-1)the Doctor Foundation of Southwest University (Grant No. SWU110038)the Fundamental Research Funds for the Central Universities of Southwest University (Grant No. XDJK2010C020)
文摘As the ultra high DC voltage grid comes into an important stage in the ‘Twelfth Five-year Plan’ of China, the requirement on the operation safety of power equipment needs to be improved. Oil-paper insulation plays a significant role as the main insulation material of many key power equipments. The space charge behaviors of oil-paper insulation not only affect the dielectric strength, but also relate to the stability and security of power transmission facilities. Until now, the research on the space charge behaviors of oil-paper insulation remains on the stage of objective description and phenomenon explanation, thus it is very urgent to make some feature extractions on the test results in order to further investigate the DC space charge behaviors of oil-paper insulation. In this paper, based on the large numbers of test data in the first stage, data mining and feature extractions were performed on the DC space charge behavior of oil-paper insulation. The variation laws of some key characteristic parameters obtained in different experiment conditions such as the total charge injection amount, apparent charge mobility, and trap energy distribution were analyzed. In addition, the distribution of trapping level inside oil-paper was calculated by using the PEA test results based on the mechanism of the isothermal decay current, which realized the approximate calculation of trap depth by charge decay characteristics. What’s more, the exponential injection and decay equations of DC space charge changing with time were acquired for the first time, and the physical meanings of related parameters were defined. This has laid a foundation for the prediction and simulation of space charge in the oil-paper insulation.
基金supported in part by the Basic Research Program of China National Basic Research Program of China(973 Program)under Grant 2011CB2094-01in part by the National Natural Science Foundations of China under Grant 51322703.
文摘The DC electric field is sometimes accompanied by space charges caused by the partial discharge in the air,which impacts DC electric field measurements.This paper describes the impact factors in the calibration and application of the field mill for measuring the DC electric field with space charges.First,the influence of the space charges on calibration results is evaluated and discussed.Then,both the impact of the height of the meter probe above the ground and the touch resistance between the ground and the meter on the measurement results are investigated.Correct calibration and application methods are presented.The results are expected to be of use to engineers for conducting accurate measurements of the DC electric field with space charges.
