In this paper,propagation characteristics of electromagnetic electron cyclotron(EMEC)waves based on kappa-Maxwellian distribution have been investigated to invoke the interplay of the electric field parallel to the Ea...In this paper,propagation characteristics of electromagnetic electron cyclotron(EMEC)waves based on kappa-Maxwellian distribution have been investigated to invoke the interplay of the electric field parallel to the Earth’s magnetic field and auroral trapped electrons.The dispersion relation for EMEC waves in kappa-Maxwellian distributed plasma has been derived using the contribution of the parallel electric field and trapped electron speed.Numerical results show that the presence of the electric field has a stimulating effect on growth rate,which is more pronounced at low values of wave number.It is also observed that as the threshold value of trapped electron speed is surpassed,it dominates the effect of the parallel electric field and EMEC instability is enhanced significantly.The electric field acts as another source of free energy,and growth can be obtained even in the absence of trapped electron drift speed and for very small values of temperature anisotropy.Thus the present study reveals the interplay of the parallel electric field and trapped electron speed on the excitation of EMEC waves in the auroral region.展开更多
We study the Landau resonance between geodesic acoustic mode（GAM） and trapped electrons as a GAM’s collisionless damping. The assumption of ˉωde 〈〈ωbeis adopted.The damping rate induced by trapped electrons is...We study the Landau resonance between geodesic acoustic mode（GAM） and trapped electrons as a GAM’s collisionless damping. The assumption of ˉωde 〈〈ωbeis adopted.The damping rate induced by trapped electrons is found to be an increasing function of q. In low q range, circulating-ion-induced damping rate is larger than that induced by trapped electrons.As q increases, the latter becomes larger than the former. The reason is that trapped electrons’ resonant velocity is close to vtefrom the lower side, whiles circulating ions’ resonant velocity gets bigger further from vti. So the number of resonant trapped electrons increases, whiles the number of resonant circulating ions decreases. The amplitude of damping rate induced by trapped electrons in the edge plasma can be comparable to that induced by circulating ions in the low q range.Another phenomenon we found is that in the chosen range of, the damping caused by trapped electrons has a maximum value at point εq for different q. The reason is that as is close to q,trapped electorns’ resonant velocity is close to vte.展开更多
The ion temperature gradient(ITG)mode in the presence of impurity ions and trapped electrons(TEs)is numerically investigated in tokamak plasmas with hollow density profiles,using the gyrokinetic integral eigenmode equ...The ion temperature gradient(ITG)mode in the presence of impurity ions and trapped electrons(TEs)is numerically investigated in tokamak plasmas with hollow density profiles,using the gyrokinetic integral eigenmode equation.It is found that in the inverted density plasma,the increase of the ITG enhances the growth rate and frequency of the ITG,and the density gradient plays an important role in the ITG modes.For weak density gradient situations,the trapped electron effects increase the instability of the ITG,while the impurity has an obviously stabilizing effect.For the strong density gradient cases,both the impurities and trapped electrons enhance the ITG instabilities.In addition,it is shown that the growth rate of the ITG decreases with positive magnetic shear s while the real frequency increases with positive magnetic shear.The growth rate of the ITG increases with negative magnetic shear s while the real frequency decreases with negative magnetic shear.The length of the calculated mode structure in the positive and negative magnetic shear intervals is also presented.展开更多
The formation and propagation of nonlinear dust acoustic waves（DAWs） as solitary and solitary/shock waves in an unmagnetized, homogeneous, dissipative and collisionless dusty plasma comprising negatively charged mic...The formation and propagation of nonlinear dust acoustic waves（DAWs） as solitary and solitary/shock waves in an unmagnetized, homogeneous, dissipative and collisionless dusty plasma comprising negatively charged micron sized dust grains in the presence of free and trapped electrons with singly charged non-thermal positive ions is discussed in detail. The evolution characteristics of the solitary and shock waves are studied by deriving a modified Korteweg–de Vries–Burgers（mKdV–Burgers） equation using the reductive perturbation method. The mKdV–Burgers equation is solved considering the presence（absence） of dissipation. In the absence of dissipation the system admits a solitary wave solution, whereas in the presence of dissipation the system admits shock waves（both monotonic and oscillatory） as well as a combination of solitary and shock wave solutions. Standard methods of solving the evolution equation of shock（solitary） waves are used. The results are discussed numerically using standard values of plasma parameters. The findings may be useful for better understanding of formation and propagation of waves in astrophysical plasma.展开更多
The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied, A computer code for solving the Fokker-Planck equation in a toroidal geometry is developed and employed. The co...The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied, A computer code for solving the Fokker-Planck equation in a toroidal geometry is developed and employed. The code is suitable for various auxiliary heating and current drive schemes in tokamak plasmas. The influence of the resonance regime on the current drive efficiency as well as the influence of trapped particle fraction on the current drive efficiency are emphasized. It is shown that, as an electrostatic force, the lower hybrid wave causes some of the trapped electrons to be untrapped and lose their energy, which can cut the LHCD efficiency by about 30%. The ITER scaling law is also used to estimate the trapped electron effects.展开更多
An investigation is carried out for understanding the properties of ion–acoustic（IA） solitary waves in an inhomogeneous magnetized electron-ion plasma with field-aligned sheared flow under the impact of q-nonextens...An investigation is carried out for understanding the properties of ion–acoustic（IA） solitary waves in an inhomogeneous magnetized electron-ion plasma with field-aligned sheared flow under the impact of q-nonextensive trapped electrons. The Schamel equation and its stationary solution in the form of solitary waves are obtained for this inhomogeneous plasma. It is shown that the amplitude of IA solitary waves increases with higher trapping efficiency（β）, while the width remains almost the same. Further, it is found that the amplitude of the solitary waves decreases with enhanced normalized drift speed, shear flow parameter and the population of the energetic particles. The size of the nonlinear solitary structures is calculated to be a few hundred meters and it is pointed out that the present results are useful to understand the solar wind plasma.展开更多
The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied. The influence of the resonance regime on the current drive efficiency as well as the influence of trapped parti...The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied. The influence of the resonance regime on the current drive efficiency as well as the influence of trapped particle fraction on the current drive efficiency are emphasized.展开更多
In this work, the effects of superthermal and trapped electrons on the oblique propa- gation of nonlinear dust-acoustic waves in a magnetized dusty （complex） plasma are investigated. The dynamic of electrons is simu...In this work, the effects of superthermal and trapped electrons on the oblique propa- gation of nonlinear dust-acoustic waves in a magnetized dusty （complex） plasma are investigated. The dynamic of electrons is simulated by the generalized Lorentzian （k） distribution function （DF）. The dust grains are cold and their dynamics are simulated by hydrodynamic equations. Using the standard reductive perturbation technique （RPT） a nonlinear modified Korteweg-de Vries （mKdV） equation is derived. Two types of solitary waves; fast and slow dust acoustic solitons, exist in this plasma. Calculations reveal that compressive solitary structures are likely to propagate in this plasma where dust grains are negatively （or positively） charged. The properties of dust acoustic solitons （DASs） are also investigated numerically.展开更多
The propagation properties of ion-acoustic solitary and shock waves in the magnetized viscous plasma with nonthermal trapped electrons are investigated.The Cairns-Gurevich distribution as the electron distribution is ...The propagation properties of ion-acoustic solitary and shock waves in the magnetized viscous plasma with nonthermal trapped electrons are investigated.The Cairns-Gurevich distribution as the electron distribution is considered to describe the plasma nonthermality and particle trapping.By adopting the reductive perturbation technique,we derived the nonlinear Schamel-Korteweg-de Vries-Burgers(SKdVB)equation,and then obtained the ion-acoustic shock and solitary wave solutions of the SKdVB equation for different limiting cases.It is found that the impact of nonthermal parameterα,external magnetic fieldΩ,obliqueness lz,wave speed U0,and the ion kinematic viscosityη0can significantly change the characteristics of the shock and solitary waves.These results may be useful for better understanding the propagation of nonlinear structures in space(i.e.Earth's magnetosphere and ionosphere,auroral regions)and laboratory plasma with nonthermal trapped electrons.展开更多
In EAST,synchrotron radiation is emitted by runaway electrons in the infrared band,which can be observed by infrared cameras.This synchrotron radiation is mainly emitted by passing runaway electrons with tens of MeV e...In EAST,synchrotron radiation is emitted by runaway electrons in the infrared band,which can be observed by infrared cameras.This synchrotron radiation is mainly emitted by passing runaway electrons with tens of MeV energy.A common feature of radiation dominated by passing runaway electrons is that it is strongest on the high field side.However,the deeply trapped runaway electrons cannot reach the high field side in principle.Therefore,in this case,the high field side radiation is expected to be weak.This paper reports for the first time that the synchrotron radiation from trapped runaway electrons dominates that from passing runaway electrons and is identifiable in an image.Although the synchrotron radiation dominated by trapped runaway electrons can be observed in experiment,the proportion of trapped runaway electrons is very low.展开更多
The generation of economically valuable chemicals through electrocatalytic CO_(2)reduction reaction(CO_(2)RR)is a highly attractive strategy for achieving the carbon cycle.Bismuth(Bi)is a prospective element due to th...The generation of economically valuable chemicals through electrocatalytic CO_(2)reduction reaction(CO_(2)RR)is a highly attractive strategy for achieving the carbon cycle.Bismuth(Bi)is a prospective element due to the high selectivity for formate.Researches demonstrate the Bi–O bonds have a significant effect on the key*OCHO intermediate.Herein,we report a F-doped catalyst that displays remarkable performance in generating formate in pH-universal electrolytes.Specifically,the as-prepared F-Bi/BOC@GO achieves formate Faradaic efficiencies(FEformate)around 95%in a wide range of pH from 1 to 13.6.Furthermore,at an industrial level,current density of 200 mA cm^(-2),the F-Bi/BOC@GO catalyst shows a much more stable FE_(formate)than the catalyst without introducing F.In situ Raman reveals that the doped F can greatly improve the stability of Bi–O bonds during the electroreduction process.DFT calculations further demonstrate that fluorine doping raises the energy barrier for oxygen desorption from Bi–O motifs,thus enhancing the stability of active sites.Combined with X-ray photoelectron spectroscopy(XPS),the doped F acts as an electron trapping,which may direct electrons towards Bi–Bi bonds,thus protecting the key Bi–O motif.This work reveals the critical role of fluorine in stabilizing Bi–O active centers across a wide pH range,maintaining high formate Faradaic efficiency for a longer time than the catalyst without fluorine introduction.展开更多
Available online Further oxidation of NH3produced via photocatalytic N_(2)fixation represents a promising strategy to enhance the economic value of N_(2)fixation.This work employs first-principles density functional t...Available online Further oxidation of NH3produced via photocatalytic N_(2)fixation represents a promising strategy to enhance the economic value of N_(2)fixation.This work employs first-principles density functional theory(DFT)calculations to demonstrate that incorporating Co into Ni O improves both N_(2)adsorption and activation as well as M-N electron exchange intensity.Guided by these predictions,a novel Co single-atom photocatalyst supported by nanoconfined Ni O@C nanosheets was synthesized using a direct metal atomization method,achieving high HNO_(3)production(60.54%).NH_(4)^(+)and NO_(3)^(-)production rates during N_(2)photofixation reached 67.97μmol g_(cat)^(-1)h^(-1)and 104.28μmol g_(cat)^(-1)h^(-1),respectively.The overall N_(2)→NH_(3)→HNO_(3)photofixation pathway was validated through in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and^(15)N isotopic labeling.Mechanistic studies reveal that Co single-atom introduction serves as an electron trap,enhancing photogenerated electron accumulation with a five-fold increase in carrier density compared to Ni O@C,as observed via in-situ X-ray photoelectron spectroscopy(XPS).This synergistic effect between electron traps and N2adsorption/activation sites at Co single-atom centers supports rapid N_(2)reduction kinetics.Additionally,nanoconfined ink-bottle pores in the carbon layer impede NH_(3)desorption,further boosting NO_(3)-production.This work offers a comprehensive approach to optimizing N_(2)photofixation through electron regulation and surface reaction kinetics.展开更多
The on-resistance degradations of the p-type lateral extended drain MOS transistor （pLEDMOS） with thick gate oxide under different hot carrier stress conditions are different, which has been experimentally investiga...The on-resistance degradations of the p-type lateral extended drain MOS transistor （pLEDMOS） with thick gate oxide under different hot carrier stress conditions are different, which has been experimentally investigated. This difference results from the interface trap generation and the hot electron injection, and trapping into the thick gate oxide and field oxide of the pLEDMOS transistor. An improved method to reduce the on-resistance degradations is also presented, which uses the field oxide as the gate oxide instead of the thick gate oxide. The effects are analyzed with a MEDICI simulator.展开更多
The reverse generation current under high-gate-voltage stress condition in LDD nMOSFET＇s is studied. We find that the generation current peak decreases as the stress time increases. We ascribe this finding to the dom...The reverse generation current under high-gate-voltage stress condition in LDD nMOSFET＇s is studied. We find that the generation current peak decreases as the stress time increases. We ascribe this finding to the dominating oxide trapped electrons that reduce the effective drain bias, lowering the maximal generation rate. The density of the effective trapped electrons affecting the effective drain bias is calculated with our model.展开更多
In this paper an investigation into dust acoustic sofitary waves （DASWs） in the presence of superthermM electrons and ions in a magnetized plasma with cold dust gains and trapped electrons is discussed. The dynamic ...In this paper an investigation into dust acoustic sofitary waves （DASWs） in the presence of superthermM electrons and ions in a magnetized plasma with cold dust gains and trapped electrons is discussed. The dynamic of both electrons and ions is simulated by the generalized Lorentzian （κ） distribution function （DF）. The dust grains are cold and their dynamics are studied by hydrodynamic equations. The basic set of fluid equations is reduced to modified Korteweg-de Vries （mKdV） equation using Reductive Perturbation Theory （RPT）. Two types of solitary waves, fast and slow dust acoustic soliton （DAS） exist in this plasma. Caiculations reveal that compressive solitary structures are possibly propagated in the plasma where dust grains are negatively （or positively） charged. The properties of DASs are also investigated numerically.展开更多
Photoelectron is the foundation of latent image formation, the decay process of photoelectrons is influenced by all kinds of trapping centres in silver halide. By analysing the mechanism of latent image formation it i...Photoelectron is the foundation of latent image formation, the decay process of photoelectrons is influenced by all kinds of trapping centres in silver halide. By analysing the mechanism of latent image formation it is found that electron trap, hole trap, and one kind of recombination centre where free electron and trapped hole recombine are the main trapping centres in silver halide. Different trapping centres have different influences on the photoelectron behaviour. The effects of all kinds of typical trapping centres on the decay of photoelectrons are systematically investigated by solving the photoelectron decay kinetic equations. The results are in agreement with those obtained in the microwave absorption dielectric spectrum experiment.展开更多
The optical absorption spectra of BaF2-x Clx ：Eu^2＋ after ultraviolet （UV） light excitation were investigated. The differences between the absorption spectra after and before excitation （DAS） were observed. The ...The optical absorption spectra of BaF2-x Clx ：Eu^2＋ after ultraviolet （UV） light excitation were investigated. The differences between the absorption spectra after and before excitation （DAS） were observed. The DAS increase at both the high and the low energy side of F band in BaF2-xClx ： Eu^2 ＋ after 245 nm UV light excitation. The bleach effect of UV light and the absorption of electrons in the valence band may account for the former and the formation of Fa centres （association of F（Cl^-） centres）, whose absorption band matches the HeNe laser better, may explain the latter. In the write-in process, the transfer of electrons is via tunneling, In the readout process, the transfer of electrons captured in F（F^-） and Fa centres is more likely via tunneling, and that of F（Cl^- ） centres is more likely via conduction band.展开更多
The long afterglow phosphor CaAl2O4： Eu^2＋, Nd^3＋ was prepared by the high temperature solid-state reaction method, and the influence of La^3＋ and Dy^3＋ on the properties of the long afterglow phosphor was studie...The long afterglow phosphor CaAl2O4： Eu^2＋, Nd^3＋ was prepared by the high temperature solid-state reaction method, and the influence of La^3＋ and Dy^3＋ on the properties of the long afterglow phosphor was studied by X-ray diffiaction （XRD）, photoluminescence （PL）, and thermoluminescence （TL）. The XRD pattem shows the host phase of CaAl2O4 is produced and no impurity phase appears. The peak wavelength of the phosphor does not vary with La^3＋ and Dy^3＋ doping. It implies that the crystal field, which affects the 5d electron states of Eu^2＋, is not changed dramatically after doping of La^3＋ and Dy^3＋. The TL spectra indicate that the phosphor doped with La^3＋ or Dy^3＋ produces different depths of trap energy level. In the mechanism of long afterglow luminescence, it is considered that La^3＋ or Dy^3＋ works as trap energy level. The decay time lies on the number of electrons in the trap energy level and the rate of the electrons returning to the excitation level.展开更多
Trivalent rare-earth ions （La3＋,Pr3＋,Nd3＋,Sm3＋,Gd3＋,Tb3＋,Dy3＋,Ho3＋,Er3＋,Tm3＋,and Yb3＋） were investigated as the codoped auxiliary sensitizer for the electron trapping materials SrS：Eu2＋ in order to enha...Trivalent rare-earth ions （La3＋,Pr3＋,Nd3＋,Sm3＋,Gd3＋,Tb3＋,Dy3＋,Ho3＋,Er3＋,Tm3＋,and Yb3＋） were investigated as the codoped auxiliary sensitizer for the electron trapping materials SrS：Eu2＋ in order to enhance the fluorescence properties.It was found that Sm3＋ and Tb3＋ had the best photoluminescence stimulated luminescence （PSL） effect among the selected trivalent rare-earth ions.All the SrS：Eu2＋ samples doped by different trivalent rare-earth ions could be stimulated by 980 nm laser after being exposed to the conventional sunlight,and they emitted PSL with the peak located at 615 nm.The result also indicated that some co-doped rare earth ions could increase fluorescence intensities of the traditional electron trapping materials SrS：Eu2＋.展开更多
Silicon-on-insulator（SOI） devices are sensitive to the total ionizing dose effect due to the existence of buried oxide.In this paper,an extra single-step Si ion implantation into buried oxide layer prior to the norm...Silicon-on-insulator（SOI） devices are sensitive to the total ionizing dose effect due to the existence of buried oxide.In this paper,an extra single-step Si ion implantation into buried oxide layer prior to the normal complementary metal–oxide–semiconductor transistor（CMOS） process is used to harden the SOI wafer.The top-Si quality of the hardened SOI wafer is confirmed to be good enough for device manufacturing through various characterization methods.The radiation experiments show that the total ionizing dose tolerance of the Si implanted SOI device is improved significantly.The metastable electron traps introduced by Si implantation is also investigated by electrical stress.The results show that these traps are very instable,and electrons will tunnel into or out of the metastable electron traps quickly after hot-electroninjection or hot-hole-injection.展开更多
基金This research was supported by the GC University grant No.241/ORIC/19 dated 27-08-2019National Natural Science Foundation of China Grant No.41874190.
文摘In this paper,propagation characteristics of electromagnetic electron cyclotron(EMEC)waves based on kappa-Maxwellian distribution have been investigated to invoke the interplay of the electric field parallel to the Earth’s magnetic field and auroral trapped electrons.The dispersion relation for EMEC waves in kappa-Maxwellian distributed plasma has been derived using the contribution of the parallel electric field and trapped electron speed.Numerical results show that the presence of the electric field has a stimulating effect on growth rate,which is more pronounced at low values of wave number.It is also observed that as the threshold value of trapped electron speed is surpassed,it dominates the effect of the parallel electric field and EMEC instability is enhanced significantly.The electric field acts as another source of free energy,and growth can be obtained even in the absence of trapped electron drift speed and for very small values of temperature anisotropy.Thus the present study reveals the interplay of the parallel electric field and trapped electron speed on the excitation of EMEC waves in the auroral region.
文摘We study the Landau resonance between geodesic acoustic mode（GAM） and trapped electrons as a GAM’s collisionless damping. The assumption of ˉωde 〈〈ωbeis adopted.The damping rate induced by trapped electrons is found to be an increasing function of q. In low q range, circulating-ion-induced damping rate is larger than that induced by trapped electrons.As q increases, the latter becomes larger than the former. The reason is that trapped electrons’ resonant velocity is close to vtefrom the lower side, whiles circulating ions’ resonant velocity gets bigger further from vti. So the number of resonant trapped electrons increases, whiles the number of resonant circulating ions decreases. The amplitude of damping rate induced by trapped electrons in the edge plasma can be comparable to that induced by circulating ions in the low q range.Another phenomenon we found is that in the chosen range of, the damping caused by trapped electrons has a maximum value at point εq for different q. The reason is that as is close to q,trapped electorns’ resonant velocity is close to vte.
基金supported by the National Key R&D Program of China(Nos.2018YFE0303102 and2017YFE0301702)US SciDAC GSEP+2 种基金the NSFC(Nos.11905109 and 11947238)the China Postdoctoral Science Foundation(No.2018M640230)the Fundamental Research Funds for the Central Universities,Nankai University(63191351)。
文摘The ion temperature gradient(ITG)mode in the presence of impurity ions and trapped electrons(TEs)is numerically investigated in tokamak plasmas with hollow density profiles,using the gyrokinetic integral eigenmode equation.It is found that in the inverted density plasma,the increase of the ITG enhances the growth rate and frequency of the ITG,and the density gradient plays an important role in the ITG modes.For weak density gradient situations,the trapped electron effects increase the instability of the ITG,while the impurity has an obviously stabilizing effect.For the strong density gradient cases,both the impurities and trapped electrons enhance the ITG instabilities.In addition,it is shown that the growth rate of the ITG decreases with positive magnetic shear s while the real frequency increases with positive magnetic shear.The growth rate of the ITG increases with negative magnetic shear s while the real frequency decreases with negative magnetic shear.The length of the calculated mode structure in the positive and negative magnetic shear intervals is also presented.
文摘The formation and propagation of nonlinear dust acoustic waves（DAWs） as solitary and solitary/shock waves in an unmagnetized, homogeneous, dissipative and collisionless dusty plasma comprising negatively charged micron sized dust grains in the presence of free and trapped electrons with singly charged non-thermal positive ions is discussed in detail. The evolution characteristics of the solitary and shock waves are studied by deriving a modified Korteweg–de Vries–Burgers（mKdV–Burgers） equation using the reductive perturbation method. The mKdV–Burgers equation is solved considering the presence（absence） of dissipation. In the absence of dissipation the system admits a solitary wave solution, whereas in the presence of dissipation the system admits shock waves（both monotonic and oscillatory） as well as a combination of solitary and shock wave solutions. Standard methods of solving the evolution equation of shock（solitary） waves are used. The results are discussed numerically using standard values of plasma parameters. The findings may be useful for better understanding of formation and propagation of waves in astrophysical plasma.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10675043, 10575031 and 10675042）.
文摘The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied, A computer code for solving the Fokker-Planck equation in a toroidal geometry is developed and employed. The code is suitable for various auxiliary heating and current drive schemes in tokamak plasmas. The influence of the resonance regime on the current drive efficiency as well as the influence of trapped particle fraction on the current drive efficiency are emphasized. It is shown that, as an electrostatic force, the lower hybrid wave causes some of the trapped electrons to be untrapped and lose their energy, which can cut the LHCD efficiency by about 30%. The ITER scaling law is also used to estimate the trapped electron effects.
文摘An investigation is carried out for understanding the properties of ion–acoustic（IA） solitary waves in an inhomogeneous magnetized electron-ion plasma with field-aligned sheared flow under the impact of q-nonextensive trapped electrons. The Schamel equation and its stationary solution in the form of solitary waves are obtained for this inhomogeneous plasma. It is shown that the amplitude of IA solitary waves increases with higher trapping efficiency（β）, while the width remains almost the same. Further, it is found that the amplitude of the solitary waves decreases with enhanced normalized drift speed, shear flow parameter and the population of the energetic particles. The size of the nonlinear solitary structures is calculated to be a few hundred meters and it is pointed out that the present results are useful to understand the solar wind plasma.
基金Supported by the National Natural Science Foundation of China （10675043, 10575031 and 10675042）
文摘The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied. The influence of the resonance regime on the current drive efficiency as well as the influence of trapped particle fraction on the current drive efficiency are emphasized.
文摘In this work, the effects of superthermal and trapped electrons on the oblique propa- gation of nonlinear dust-acoustic waves in a magnetized dusty （complex） plasma are investigated. The dynamic of electrons is simulated by the generalized Lorentzian （k） distribution function （DF）. The dust grains are cold and their dynamics are simulated by hydrodynamic equations. Using the standard reductive perturbation technique （RPT） a nonlinear modified Korteweg-de Vries （mKdV） equation is derived. Two types of solitary waves; fast and slow dust acoustic solitons, exist in this plasma. Calculations reveal that compressive solitary structures are likely to propagate in this plasma where dust grains are negatively （or positively） charged. The properties of dust acoustic solitons （DASs） are also investigated numerically.
文摘The propagation properties of ion-acoustic solitary and shock waves in the magnetized viscous plasma with nonthermal trapped electrons are investigated.The Cairns-Gurevich distribution as the electron distribution is considered to describe the plasma nonthermality and particle trapping.By adopting the reductive perturbation technique,we derived the nonlinear Schamel-Korteweg-de Vries-Burgers(SKdVB)equation,and then obtained the ion-acoustic shock and solitary wave solutions of the SKdVB equation for different limiting cases.It is found that the impact of nonthermal parameterα,external magnetic fieldΩ,obliqueness lz,wave speed U0,and the ion kinematic viscosityη0can significantly change the characteristics of the shock and solitary waves.These results may be useful for better understanding the propagation of nonlinear structures in space(i.e.Earth's magnetosphere and ionosphere,auroral regions)and laboratory plasma with nonthermal trapped electrons.
基金the National Natural Science Foundation of China(Grant No.11775263)the National Magnetic Confinement Fusion Energy Research Project of China(Grant No.2015GB111003).
文摘In EAST,synchrotron radiation is emitted by runaway electrons in the infrared band,which can be observed by infrared cameras.This synchrotron radiation is mainly emitted by passing runaway electrons with tens of MeV energy.A common feature of radiation dominated by passing runaway electrons is that it is strongest on the high field side.However,the deeply trapped runaway electrons cannot reach the high field side in principle.Therefore,in this case,the high field side radiation is expected to be weak.This paper reports for the first time that the synchrotron radiation from trapped runaway electrons dominates that from passing runaway electrons and is identifiable in an image.Although the synchrotron radiation dominated by trapped runaway electrons can be observed in experiment,the proportion of trapped runaway electrons is very low.
基金supported by the National Natural Science Foundation of China(22322805,22178104,U22B20143,U24A20546)Shanghai Municipal Science and Technology Major Project+1 种基金the Shanghai Scientific and Technological Innovation Project(22dz1205900)the Fundamental Research Funds for the Central Universities,and Shanghai Rising-Star Program(23QA1402200)。
文摘The generation of economically valuable chemicals through electrocatalytic CO_(2)reduction reaction(CO_(2)RR)is a highly attractive strategy for achieving the carbon cycle.Bismuth(Bi)is a prospective element due to the high selectivity for formate.Researches demonstrate the Bi–O bonds have a significant effect on the key*OCHO intermediate.Herein,we report a F-doped catalyst that displays remarkable performance in generating formate in pH-universal electrolytes.Specifically,the as-prepared F-Bi/BOC@GO achieves formate Faradaic efficiencies(FEformate)around 95%in a wide range of pH from 1 to 13.6.Furthermore,at an industrial level,current density of 200 mA cm^(-2),the F-Bi/BOC@GO catalyst shows a much more stable FE_(formate)than the catalyst without introducing F.In situ Raman reveals that the doped F can greatly improve the stability of Bi–O bonds during the electroreduction process.DFT calculations further demonstrate that fluorine doping raises the energy barrier for oxygen desorption from Bi–O motifs,thus enhancing the stability of active sites.Combined with X-ray photoelectron spectroscopy(XPS),the doped F acts as an electron trapping,which may direct electrons towards Bi–Bi bonds,thus protecting the key Bi–O motif.This work reveals the critical role of fluorine in stabilizing Bi–O active centers across a wide pH range,maintaining high formate Faradaic efficiency for a longer time than the catalyst without fluorine introduction.
基金supported by the National Natural Science Foundation of China(No.62004143)the Key Research and Development Program of Gansu Province-Industrial Project under Grant(No.25YFGA058)+4 种基金the Key Talent Project Foundation of Gansu Province(No.2025RCXM066)the Gansu Provincial Department of Education:Industrial Support Plan Project(No.2025CYZC-005)the Key R&D Program of Hubei Province(No.2022BAA084)the Science and Technology Project of Lanzhou(No.2024-3-42)the Fundamental Research Funds for the Central Universities(No.331920240059)。
文摘Available online Further oxidation of NH3produced via photocatalytic N_(2)fixation represents a promising strategy to enhance the economic value of N_(2)fixation.This work employs first-principles density functional theory(DFT)calculations to demonstrate that incorporating Co into Ni O improves both N_(2)adsorption and activation as well as M-N electron exchange intensity.Guided by these predictions,a novel Co single-atom photocatalyst supported by nanoconfined Ni O@C nanosheets was synthesized using a direct metal atomization method,achieving high HNO_(3)production(60.54%).NH_(4)^(+)and NO_(3)^(-)production rates during N_(2)photofixation reached 67.97μmol g_(cat)^(-1)h^(-1)and 104.28μmol g_(cat)^(-1)h^(-1),respectively.The overall N_(2)→NH_(3)→HNO_(3)photofixation pathway was validated through in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and^(15)N isotopic labeling.Mechanistic studies reveal that Co single-atom introduction serves as an electron trap,enhancing photogenerated electron accumulation with a five-fold increase in carrier density compared to Ni O@C,as observed via in-situ X-ray photoelectron spectroscopy(XPS).This synergistic effect between electron traps and N2adsorption/activation sites at Co single-atom centers supports rapid N_(2)reduction kinetics.Additionally,nanoconfined ink-bottle pores in the carbon layer impede NH_(3)desorption,further boosting NO_(3)-production.This work offers a comprehensive approach to optimizing N_(2)photofixation through electron regulation and surface reaction kinetics.
文摘The on-resistance degradations of the p-type lateral extended drain MOS transistor （pLEDMOS） with thick gate oxide under different hot carrier stress conditions are different, which has been experimentally investigated. This difference results from the interface trap generation and the hot electron injection, and trapping into the thick gate oxide and field oxide of the pLEDMOS transistor. An improved method to reduce the on-resistance degradations is also presented, which uses the field oxide as the gate oxide instead of the thick gate oxide. The effects are analyzed with a MEDICI simulator.
文摘The reverse generation current under high-gate-voltage stress condition in LDD nMOSFET＇s is studied. We find that the generation current peak decreases as the stress time increases. We ascribe this finding to the dominating oxide trapped electrons that reduce the effective drain bias, lowering the maximal generation rate. The density of the effective trapped electrons affecting the effective drain bias is calculated with our model.
文摘In this paper an investigation into dust acoustic sofitary waves （DASWs） in the presence of superthermM electrons and ions in a magnetized plasma with cold dust gains and trapped electrons is discussed. The dynamic of both electrons and ions is simulated by the generalized Lorentzian （κ） distribution function （DF）. The dust grains are cold and their dynamics are studied by hydrodynamic equations. The basic set of fluid equations is reduced to modified Korteweg-de Vries （mKdV） equation using Reductive Perturbation Theory （RPT）. Two types of solitary waves, fast and slow dust acoustic soliton （DAS） exist in this plasma. Caiculations reveal that compressive solitary structures are possibly propagated in the plasma where dust grains are negatively （or positively） charged. The properties of DASs are also investigated numerically.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10274017 and 10354001）, and the Natural Science Foundation of Hebei Province, China （Grant Nos 103097 and 603138）.
文摘Photoelectron is the foundation of latent image formation, the decay process of photoelectrons is influenced by all kinds of trapping centres in silver halide. By analysing the mechanism of latent image formation it is found that electron trap, hole trap, and one kind of recombination centre where free electron and trapped hole recombine are the main trapping centres in silver halide. Different trapping centres have different influences on the photoelectron behaviour. The effects of all kinds of typical trapping centres on the decay of photoelectrons are systematically investigated by solving the photoelectron decay kinetic equations. The results are in agreement with those obtained in the microwave absorption dielectric spectrum experiment.
文摘The optical absorption spectra of BaF2-x Clx ：Eu^2＋ after ultraviolet （UV） light excitation were investigated. The differences between the absorption spectra after and before excitation （DAS） were observed. The DAS increase at both the high and the low energy side of F band in BaF2-xClx ： Eu^2 ＋ after 245 nm UV light excitation. The bleach effect of UV light and the absorption of electrons in the valence band may account for the former and the formation of Fa centres （association of F（Cl^-） centres）, whose absorption band matches the HeNe laser better, may explain the latter. In the write-in process, the transfer of electrons is via tunneling, In the readout process, the transfer of electrons captured in F（F^-） and Fa centres is more likely via tunneling, and that of F（Cl^- ） centres is more likely via conduction band.
基金the National Natu-ral Science Foundation of China (No. 50204002)the National High-Tech Research and Development Program of China (No. 2001AA324080)
文摘The long afterglow phosphor CaAl2O4： Eu^2＋, Nd^3＋ was prepared by the high temperature solid-state reaction method, and the influence of La^3＋ and Dy^3＋ on the properties of the long afterglow phosphor was studied by X-ray diffiaction （XRD）, photoluminescence （PL）, and thermoluminescence （TL）. The XRD pattem shows the host phase of CaAl2O4 is produced and no impurity phase appears. The peak wavelength of the phosphor does not vary with La^3＋ and Dy^3＋ doping. It implies that the crystal field, which affects the 5d electron states of Eu^2＋, is not changed dramatically after doping of La^3＋ and Dy^3＋. The TL spectra indicate that the phosphor doped with La^3＋ or Dy^3＋ produces different depths of trap energy level. In the mechanism of long afterglow luminescence, it is considered that La^3＋ or Dy^3＋ works as trap energy level. The decay time lies on the number of electrons in the trap energy level and the rate of the electrons returning to the excitation level.
基金Project supported by the National Natural Science Foundations of China (20876002, 20976002)the Beijing Natural Science Foundation (2091002)Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality
文摘Trivalent rare-earth ions （La3＋,Pr3＋,Nd3＋,Sm3＋,Gd3＋,Tb3＋,Dy3＋,Ho3＋,Er3＋,Tm3＋,and Yb3＋） were investigated as the codoped auxiliary sensitizer for the electron trapping materials SrS：Eu2＋ in order to enhance the fluorescence properties.It was found that Sm3＋ and Tb3＋ had the best photoluminescence stimulated luminescence （PSL） effect among the selected trivalent rare-earth ions.All the SrS：Eu2＋ samples doped by different trivalent rare-earth ions could be stimulated by 980 nm laser after being exposed to the conventional sunlight,and they emitted PSL with the peak located at 615 nm.The result also indicated that some co-doped rare earth ions could increase fluorescence intensities of the traditional electron trapping materials SrS：Eu2＋.
文摘Silicon-on-insulator（SOI） devices are sensitive to the total ionizing dose effect due to the existence of buried oxide.In this paper,an extra single-step Si ion implantation into buried oxide layer prior to the normal complementary metal–oxide–semiconductor transistor（CMOS） process is used to harden the SOI wafer.The top-Si quality of the hardened SOI wafer is confirmed to be good enough for device manufacturing through various characterization methods.The radiation experiments show that the total ionizing dose tolerance of the Si implanted SOI device is improved significantly.The metastable electron traps introduced by Si implantation is also investigated by electrical stress.The results show that these traps are very instable,and electrons will tunnel into or out of the metastable electron traps quickly after hot-electroninjection or hot-hole-injection.
