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 this paper,we analyze one reconnection event observed by the Magnetospheric Multiscale(MMS)mission at the earth’s magnetopause.In this event,the spacecraft crossed the reconnection current sheet from the magnetosp...In this paper,we analyze one reconnection event observed by the Magnetospheric Multiscale(MMS)mission at the earth’s magnetopause.In this event,the spacecraft crossed the reconnection current sheet from the magnetospheric side to the magnetosheath side,and whistler waves were observed on both the magnetospheric and magnetosheath sides.On the magnetospheric side,the whistler waves propagated quasi-parallel to the magnetic field and toward the X-line,while on the magnetosheath side they propagated almost anti-parallel to the magnetic field and away from the X-line.Associated with the enhancement of the whistler waves,we find that the fluxes of energetic electrons are concentrated around the pitch angle 90°when their energies are higher than the minimum energy that is necessary for the resonant interactions between the energetic electrons and whistler waves.This observation provides in situ observational evidence of resonant interactions between energetic electrons and whistler waves in the magnetic reconnection.展开更多
The basic properties of dust-ion-acoustic （DIA） shock waves in an unmagnetized dusty plasma （containing inertial ions, kappa distributed electrons with two distinct temperatures, and negatively charged immobile dus...The basic properties of dust-ion-acoustic （DIA） shock waves in an unmagnetized dusty plasma （containing inertial ions, kappa distributed electrons with two distinct temperatures, and negatively charged immobile dust grains） are investi- gated both numerically and analytically. The hydrodynamic equation for inertial ions has been used to derive the Burgers equation. The effects of superthermal bi-kappa electrons and ion kinematic viscosity, which are found to modify the basic features of DIA shock waves significantly, are briefly discussed.展开更多
In this paper we show that two significant phenomena of magnetospheric chorus emission can be explained by the participation of beam-like electron structures,created by Landau-resonant interaction with growing oblique...In this paper we show that two significant phenomena of magnetospheric chorus emission can be explained by the participation of beam-like electron structures,created by Landau-resonant interaction with growing oblique whistler waves.The first concerns the widely observed spectral gap near half the electron cyclotron frequency Ωe;the second is related to the observation of very obliquely propagating lower-band waves that cannot be directly generated by temperature anisotropy.Concerning the gap,kinetic dispersion theory reveals that interference of the beam-related cyclotron mode ω~Ωe-kVb with the conventional whistler mode leads to mode splitting and the appearance of a ’forbidden’ area in the ω-k space.Thereby the beam velocity appears as an essential parameter.It is directly related to the phase velocity of the most unstable whistler wave mode,which is close to VAe/2 for sufficiently hot electrons(VAe is the electron Alfven velocity).To clarify the second point,we show that Landau-resonant beams with Vb Vb<VAe/2,which arise in cold plasmas from unstable upper-band waves,are able to generate lower-band whistler mode waves at very oblique propagation(θ≥60°).Our studies demonstrate the important role of Landau-resonant electrons in nonlinear whistler wave generation in the magnetosphere.展开更多
Ion-acoustic solitary (IAS) waves in electron-positron-ion (e-p-i) plasma have been of interest to many researchers probably due to their relevance in understanding the Universe. However, the study of non-linear ion-a...Ion-acoustic solitary (IAS) waves in electron-positron-ion (e-p-i) plasma have been of interest to many researchers probably due to their relevance in understanding the Universe. However, the study of non-linear ion-acoustic waves in e-p-i plasma with non-thermal electrons has not been adequately studied. A theoretical investigation on non-linear IAS waves in e-p-i plasma comprising of warm inertial adiabatic fluid ions and electrons that are kappa distributed, and Boltzman distributed positron is presented here using the Sagdeev potential technique. It was found that existence domains of finite amplitude IAS waves were confined within the limits of minimum and maximum Mach numbers with varying k values. For lower values of k, the amplitude of the solitary electrostatic potential structures increased as the width decreased, while for high values, the potential amplitude decreased as the width of the solitary structure increased.展开更多
Whistler mode waves are critical emissions in magnetized plasmas that usually influence the electron dynamics in a planetary magnetosphere.In this paper,we present a unique event in the Martian magnetosphere in which ...Whistler mode waves are critical emissions in magnetized plasmas that usually influence the electron dynamics in a planetary magnetosphere.In this paper,we present a unique event in the Martian magnetosphere in which enhanced whistler mode waves(~10^(−11) V^(2)/m^(2)/Hz)with frequency of 0.1 f_(ce)-0.5 f_(ce) occurred,based on MAVEN data,exactly corresponding to a significant decrease of suprathermal electron fluxes.The diffusion coefficients are calculated by using the observed electric field wave spectra.The pitch angle diffusion coefficient can approach 10^(−2) s^(−1),which is much larger,by~100 times,than the momentum diffusion coefficient,indicating that pitch angle scattering dominates the whistler-electron resonance process.The current results can successfully explain the dropout of the suprathermal electrons in this event.This study provides direct evidence for whistler-driven electron losses in the Martian magnetosphere.展开更多
This work continues the studies on searching for plasma media with the inverse electron energy distribution function(EEDF)and providing recommendations for setting up subsequent experiments.The inverse EEDF is a distr...This work continues the studies on searching for plasma media with the inverse electron energy distribution function(EEDF)and providing recommendations for setting up subsequent experiments.The inverse EEDF is a distribution function that increases with an increase in energy at zero electron energy.The inverse EEDF plays a central role in the problem of negative conductivity.Based on the previously obtained criterion for the formation of an inverse EEDF in a spatially inhomogeneous plasma,a heuristic method is proposed that allows one to avoid resource-intensive calculations for spatially two-dimensional(2D)kinetic modeling on a large array of different glow discharges.It is shown that the conditions for EEDF inversion can be realized in two-chamber discharge structures due to violating the known Boltzmann distribution for electron density.The theoretical conclusions are validated by numerical modeling of lowpressure two-chamber inductively-coupled plasma(ICP)discharges in the COMSOL Multiphysics environment.As a result,areas of conditions with inverse EEDF were found for subsequent detailed kinetic analysis and experimental studies.展开更多
Interface modulation is an important pathway for highly efficient electromagnetic wave absorption.Herein,tailored interfaces between Fe_(3)O_(4)particles and the hexagonal-YFeO_(3)(h-YFeO_(3))framework were constructe...Interface modulation is an important pathway for highly efficient electromagnetic wave absorption.Herein,tailored interfaces between Fe_(3)O_(4)particles and the hexagonal-YFeO_(3)(h-YFeO_(3))framework were constructed via facile self-assembly.The resulting interfa-cial electron rearrangement at the heterojunction led to enhanced dielectric and magnetic loss synergy.Experimental results and density function theory(DFT)simulations demonstrate a transition in electrical properties from a half-metallic monophase to metallic Fe_(3)O_(4)/h-YFeO_(3)composites,emphasizing the advantages of the formed heterointerface.The transformation of electron behavior is also accompan-ied by a redistribution of electrons at the Fe_(3)O_(4)/h-YFeO_(3)heterojunction,leading to the accumulation of localized electrons around the Y-O-Fe band bridge,consequently enhancing the polarization.A minimum reflection loss of-34.0 dB can be achieved at 12.0 GHz and 2.0 mm thickness with an effective bandwidth of 3.3 GHz due to the abundant interfaces,enhanced polarization,and rational impedance.Thus,the synergistic effects endow the Fe_(3)O_(4)/h-YFeO_(3)composites with high performance and tunable functional properties for efficient electromagnetic absorption.展开更多
Based on the electron dynamic diffraction, phase shift of the exit wave function vs misorientation of the incident electron beam from the exact zone axis has been calculated for the [001] oriented copper. The result s...Based on the electron dynamic diffraction, phase shift of the exit wave function vs misorientation of the incident electron beam from the exact zone axis has been calculated for the [001] oriented copper. The result shows that the peak of phase shift is the maximum at the atom position as the electron beam along the exact [001] zone axis, and the peak value of phase shift decreases as increases of the misorientation. At small misorientation, i.e. less than 5 degree, change of the phase shift is minimal. The peak value of phase shift decreases significantly when the incident beam deviates form the zone axis over 10 degree and the exit wave has a planar configuration as the misoriention angle arrives -17 degree. The effect of this phase shift characteristics on the information extracted from the hologram has also been considered.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
Platinum-based(Pt)catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide(CO)poisoning.Overcoming this poisoning deactivation of Pt-based catalysts while enhancing...Platinum-based(Pt)catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide(CO)poisoning.Overcoming this poisoning deactivation of Pt-based catalysts while enhancing their catalytic activity,selectivity,and durability remains a major challenge.Herein,we propose a strategy to enhance the CO tolerance of Pt clusters(Pt_n)by introducing neighboring functionalized vip single atoms(such as Fe,Co,Ni,Cu,Sb,and Bi).Among them,antimony(Sb)single atoms(SAs)exhibit significant performance enhancement,achieving 99%CO selectivity and 33.6%CO_(2)conversion at 450℃,Experimental results and density functional theory(DFT)calculations indicate the optimization arises from the electronic interaction between neighboring functionalized Sb SAs and Pt clusters,leading to optimal 5d electron redistribution in Pt clusters compared to other functionalized vip single atoms.The redistribution of 5d electrons weaken both theσdonation andπbackdonation interactions,resulting in a weakened bond strength with CO and enhancing catalyst activity and selectivity.In situ environmental transmission electron microscopy(ETEM)further demonstrates the exception thermal stability of the catalyst,even under H_(2)at 700℃.Notably,the functionalized Sb SAs also improve CO tolerance in various heterogenous catalysts,including Co/CeO_(2),Ni/CeO_(2),Pt/Al_(2)O_(3),and Pt/CeO_(2)-C.This finding provides an effective approach to overcome the primary challenge of CO poisoning in Pt-based catalysts,making their broader applications in various industrial catalysts.展开更多
We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple elect...We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.展开更多
A generalized multiple-mode prolate spherical wave functions (PSWFs) multi-carrier with index modulation approach is proposed with the purpose of improving the spectral efficiency of PSWFs multi-carrier systems. The p...A generalized multiple-mode prolate spherical wave functions (PSWFs) multi-carrier with index modulation approach is proposed with the purpose of improving the spectral efficiency of PSWFs multi-carrier systems. The proposed method,based on the optimized multi-index modulation, does not limit the number of signals in the first and second constellations and abandons the concept of limiting the number of signals in different constellations. It successfully increases the spectrum efficiency of the system while expanding the number of modulation symbol combinations and the index dimension of PSWFs signals. The proposed method outperforms the PSWFs multi-carrier index modulation method based on optimized multiple indexes in terms of spectrum efficiency, but at the expense of system computational complexity and bit error performance. For example, with n=10 subcarriers and a bit error rate of 1×10^(-5),spectral efficiency can be raised by roughly 12.4%.展开更多
We employed random distributions and gradient descent methods for the Generator Coordinate Method(GCM)to identify effective basis wave functions,taking halo nuclei ^(6)He and ^(6)Li as examples.By comparing the ground...We employed random distributions and gradient descent methods for the Generator Coordinate Method(GCM)to identify effective basis wave functions,taking halo nuclei ^(6)He and ^(6)Li as examples.By comparing the ground state(0^(+))energy of ^(6)He and the excited state(0^(+))energy of 6 Li calculated with various random distributions and manually selected generation coordinates,we found that the heavy tail characteristic of the logistic distribution better describes the features of the halo nuclei.Subsequently,the Adam algorithm from machine learning was applied to optimize the basis wave functions,indicating that a limited number of basis wave functions can approximate the converged values.These results offer some empirical insights for selecting basis wave functions and contribute to the broader application of machine learning methods in predicting effective basis wave functions.展开更多
The motion and the energy of electrons driven by the ponderomotive force in linearly polarized high-intensity laser standing wave fields are considered. The results show that there exists a threshold laser intensity, ...The motion and the energy of electrons driven by the ponderomotive force in linearly polarized high-intensity laser standing wave fields are considered. The results show that there exists a threshold laser intensity, above which the motion of electrons incident parallel to the electric field of the laser standing waves undergoes a transition from regulation to chaos. We propose that the huge energy exchange between the electrons and the strong laser standing waves is triggered by inelastic scattering, which is related to the chaos patterns. It is shown that an electron＇s energy gain of tens of MeV can be realized for a laser intensity of 10^20 W/cm^2.展开更多
Nonplanar electron acoustic waves(NEAWs)with double spectral index-distributed hot electrons are studied under the two-temperature electrons model in a collisionless unmagnetized plasma.Using this model,the Korteweg–...Nonplanar electron acoustic waves(NEAWs)with double spectral index-distributed hot electrons are studied under the two-temperature electrons model in a collisionless unmagnetized plasma.Using this model,the Korteweg–de Vries(KdV)equation is derived in nonplanar geometry.On the basis of the solutions of KdV equation,alterations of velocity,width,and amplitude of acoustic waves having various plasma factors are investigated.Nonlinear and dispersion coefficients obtained rely on double spectral index parameters r and q,and particle densityα.The combined influence of these factors significantly alters the features of electron acoustic waves in nonplanar geometry.This study is expected to contribute to the understanding of nonlinear principles that underlie nonplanar electrostatic waves in laboratory plasmas as well as in space.展开更多
The nonlinear traveling wave vibration of rotating ferromagnetic functionally graded(FG)cylindrical shells under multi-physics fields is investigated.Grounded in the Kirchhoff-Love thin shell theory,the geometric nonl...The nonlinear traveling wave vibration of rotating ferromagnetic functionally graded(FG)cylindrical shells under multi-physics fields is investigated.Grounded in the Kirchhoff-Love thin shell theory,the geometric nonlinearity is incorporated into the model,and the constitutive equations are derived.The physical parameters of functionally graded materials(FGMs),which exhibit continuous variation across the thickness gradient,are of particular interest.The nonlinear magneto-thermoelastic governing equations are derived in accord with Hamilton's principle.The nonlinear partial differential equations are discretized with the Galerkin method,and the analytical expression of traveling wave frequencies is derived with an approximate method.The accuracy of the proposed method is validated through the comparison with the results from the literature and numerical solutions.Finally,the visualization analyses are conducted to examine the effects of key parameters on the traveling wave frequencies.The results show that the factors including the power-law index,temperature,magnetic field intensity,and rotating speed have the coupling effects with respect to the nonlinear vibration behavior.展开更多
The nonlinear propagation of dust-acoustic (DA) shock waves in three-component unmagnetized dusty plasma consisting of nonextensive electrons, Maxwellian ions and arbitrarily charged mobile dust grain has been investi...The nonlinear propagation of dust-acoustic (DA) shock waves in three-component unmagnetized dusty plasma consisting of nonextensive electrons, Maxwellian ions and arbitrarily charged mobile dust grain has been investigated. It is found that the presence of q-nonextensive electrons and ions can change the nonlinear behavior of shock wave. The standard reductive perturbation method is employed to study the basic features (phase speed, amplitude and width) of DA shock waves (DASWs) which are significantly modified by the presence of Maxwellian ions and nonextensive electrons. The present investigation can be very effective for understanding the nonlinear characteristics of the DASWs in space and laboratory dusty plasmas.展开更多
In this paper, （2＋1）-dimensional electron acoustic waves （EAW） in an unmagnetized collisionless plasma have been studied by the linearized method and the reductive perturbation technique, respectively. The disper...In this paper, （2＋1）-dimensional electron acoustic waves （EAW） in an unmagnetized collisionless plasma have been studied by the linearized method and the reductive perturbation technique, respectively. The dispersion relation and a modified Kadomtsev-Petviashvili （KP） equation have been obtained for the EAW in the plasma considering a cold electron fluid and a vortex-like hot electrons. It is found from some numerical results that the parameter β（the ratio of the free hot electron temperature to the hot trapped electron temperature） effects on the amplitude and the Width of the electron acoustic solitary waves （EASW）. It can be indicated that the free hot electron temperature and the hot trapped electron temperature have very important effect on the characters of the propagation for the EASW.展开更多
The development of next-generation electromagnetic wave(EMW)absorbers requires a shift in interface design.By employing hierarchical work function programming,we propose an approach to tune interfacial polarization dy...The development of next-generation electromagnetic wave(EMW)absorbers requires a shift in interface design.By employing hierarchical work function programming,we propose an approach to tune interfacial polarization dynamics.This method utilizes multi-gradient work functions to guide carrier migration and polarization effectively,thereby enhancing energy dissipation under alternating electromagnetic fields.Here,we constructed a 1T/2H-MoS_(2)/PPy/VS_(2) composite absorber with integrated gradient interfaces.The composite achieved a powerful absorption(RLmin)of-58.59 dB at 2.3 mm,and an effective absorption bandwidth(EAB)of 7.44 GHz at 2.5 mm,demonstrating improved broadband absorption.Radar cross-section(RCS)simulations show an EMW loss of-7.2 dB m^(2) at 0°,highlighting its potential for stealth and communication applications.This study introduces hierarchical work function programming as a promising strategy in EMW absorber design,contributing to advancements in material performance and functionality.展开更多
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supported by NSFC grants 41527804 and 41774169Key Research Program of Frontier Sciences, CAS(QYZDJ-SSW-DQC010)
文摘In this paper,we analyze one reconnection event observed by the Magnetospheric Multiscale(MMS)mission at the earth’s magnetopause.In this event,the spacecraft crossed the reconnection current sheet from the magnetospheric side to the magnetosheath side,and whistler waves were observed on both the magnetospheric and magnetosheath sides.On the magnetospheric side,the whistler waves propagated quasi-parallel to the magnetic field and toward the X-line,while on the magnetosheath side they propagated almost anti-parallel to the magnetic field and away from the X-line.Associated with the enhancement of the whistler waves,we find that the fluxes of energetic electrons are concentrated around the pitch angle 90°when their energies are higher than the minimum energy that is necessary for the resonant interactions between the energetic electrons and whistler waves.This observation provides in situ observational evidence of resonant interactions between energetic electrons and whistler waves in the magnetic reconnection.
文摘The basic properties of dust-ion-acoustic （DIA） shock waves in an unmagnetized dusty plasma （containing inertial ions, kappa distributed electrons with two distinct temperatures, and negatively charged immobile dust grains） are investi- gated both numerically and analytically. The hydrodynamic equation for inertial ions has been used to derive the Burgers equation. The effects of superthermal bi-kappa electrons and ion kinematic viscosity, which are found to modify the basic features of DIA shock waves significantly, are briefly discussed.
文摘In this paper we show that two significant phenomena of magnetospheric chorus emission can be explained by the participation of beam-like electron structures,created by Landau-resonant interaction with growing oblique whistler waves.The first concerns the widely observed spectral gap near half the electron cyclotron frequency Ωe;the second is related to the observation of very obliquely propagating lower-band waves that cannot be directly generated by temperature anisotropy.Concerning the gap,kinetic dispersion theory reveals that interference of the beam-related cyclotron mode ω~Ωe-kVb with the conventional whistler mode leads to mode splitting and the appearance of a ’forbidden’ area in the ω-k space.Thereby the beam velocity appears as an essential parameter.It is directly related to the phase velocity of the most unstable whistler wave mode,which is close to VAe/2 for sufficiently hot electrons(VAe is the electron Alfven velocity).To clarify the second point,we show that Landau-resonant beams with Vb Vb<VAe/2,which arise in cold plasmas from unstable upper-band waves,are able to generate lower-band whistler mode waves at very oblique propagation(θ≥60°).Our studies demonstrate the important role of Landau-resonant electrons in nonlinear whistler wave generation in the magnetosphere.
文摘Ion-acoustic solitary (IAS) waves in electron-positron-ion (e-p-i) plasma have been of interest to many researchers probably due to their relevance in understanding the Universe. However, the study of non-linear ion-acoustic waves in e-p-i plasma with non-thermal electrons has not been adequately studied. A theoretical investigation on non-linear IAS waves in e-p-i plasma comprising of warm inertial adiabatic fluid ions and electrons that are kappa distributed, and Boltzman distributed positron is presented here using the Sagdeev potential technique. It was found that existence domains of finite amplitude IAS waves were confined within the limits of minimum and maximum Mach numbers with varying k values. For lower values of k, the amplitude of the solitary electrostatic potential structures increased as the width decreased, while for high values, the potential amplitude decreased as the width of the solitary structure increased.
基金the National Natural Science Foundation of China grants 42230209, 42241136, 42374199, 42204171, 42274212the Natural Science Foundation of Hunan province Grant 2021JJ20010, 2023JJ20038
文摘Whistler mode waves are critical emissions in magnetized plasmas that usually influence the electron dynamics in a planetary magnetosphere.In this paper,we present a unique event in the Martian magnetosphere in which enhanced whistler mode waves(~10^(−11) V^(2)/m^(2)/Hz)with frequency of 0.1 f_(ce)-0.5 f_(ce) occurred,based on MAVEN data,exactly corresponding to a significant decrease of suprathermal electron fluxes.The diffusion coefficients are calculated by using the observed electric field wave spectra.The pitch angle diffusion coefficient can approach 10^(−2) s^(−1),which is much larger,by~100 times,than the momentum diffusion coefficient,indicating that pitch angle scattering dominates the whistler-electron resonance process.The current results can successfully explain the dropout of the suprathermal electrons in this event.This study provides direct evidence for whistler-driven electron losses in the Martian magnetosphere.
基金supported by the National Key R&D Program of China(No.2022YFE0204100)National Natural Science Foundation of China(Nos.12205067 and 12375199)the Fundamental Research Funds for the Central University(No.HIT.D?J.2023178)。
文摘This work continues the studies on searching for plasma media with the inverse electron energy distribution function(EEDF)and providing recommendations for setting up subsequent experiments.The inverse EEDF is a distribution function that increases with an increase in energy at zero electron energy.The inverse EEDF plays a central role in the problem of negative conductivity.Based on the previously obtained criterion for the formation of an inverse EEDF in a spatially inhomogeneous plasma,a heuristic method is proposed that allows one to avoid resource-intensive calculations for spatially two-dimensional(2D)kinetic modeling on a large array of different glow discharges.It is shown that the conditions for EEDF inversion can be realized in two-chamber discharge structures due to violating the known Boltzmann distribution for electron density.The theoretical conclusions are validated by numerical modeling of lowpressure two-chamber inductively-coupled plasma(ICP)discharges in the COMSOL Multiphysics environment.As a result,areas of conditions with inverse EEDF were found for subsequent detailed kinetic analysis and experimental studies.
基金supported by the National Natural Science Foundation of China(Nos.52122106 and 52027802)the“Pioneer”Research and Development Program of Zhejiang Province,China(No.2022C01230)+2 种基金the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering,China(No.2021SZ-FR005)the Space Application System of China Manned Space Program(No.KJZ-YY-NCL03)the opening fund of Key Laboratory of Rare Earths,Chinese Academy of Sciences。
文摘Interface modulation is an important pathway for highly efficient electromagnetic wave absorption.Herein,tailored interfaces between Fe_(3)O_(4)particles and the hexagonal-YFeO_(3)(h-YFeO_(3))framework were constructed via facile self-assembly.The resulting interfa-cial electron rearrangement at the heterojunction led to enhanced dielectric and magnetic loss synergy.Experimental results and density function theory(DFT)simulations demonstrate a transition in electrical properties from a half-metallic monophase to metallic Fe_(3)O_(4)/h-YFeO_(3)composites,emphasizing the advantages of the formed heterointerface.The transformation of electron behavior is also accompan-ied by a redistribution of electrons at the Fe_(3)O_(4)/h-YFeO_(3)heterojunction,leading to the accumulation of localized electrons around the Y-O-Fe band bridge,consequently enhancing the polarization.A minimum reflection loss of-34.0 dB can be achieved at 12.0 GHz and 2.0 mm thickness with an effective bandwidth of 3.3 GHz due to the abundant interfaces,enhanced polarization,and rational impedance.Thus,the synergistic effects endow the Fe_(3)O_(4)/h-YFeO_(3)composites with high performance and tunable functional properties for efficient electromagnetic absorption.
基金financially supported tional Natural Science Foundation of China No. 60271028.
文摘Based on the electron dynamic diffraction, phase shift of the exit wave function vs misorientation of the incident electron beam from the exact zone axis has been calculated for the [001] oriented copper. The result shows that the peak of phase shift is the maximum at the atom position as the electron beam along the exact [001] zone axis, and the peak value of phase shift decreases as increases of the misorientation. At small misorientation, i.e. less than 5 degree, change of the phase shift is minimal. The peak value of phase shift decreases significantly when the incident beam deviates form the zone axis over 10 degree and the exit wave has a planar configuration as the misoriention angle arrives -17 degree. The effect of this phase shift characteristics on the information extracted from the hologram has also been considered.
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.
基金financially supported by the Shanghai RisingStar Program(No.23QA1403700)the National Natural Science Foundation of China(NSFC,Grant No.U2230102)+1 种基金the sponsored by National Key Research and Development Program of China(No.2021YFB3502200)the Shanghai Technical Service Center of Science and Engineering Computing,Shanghai University.
文摘Platinum-based(Pt)catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide(CO)poisoning.Overcoming this poisoning deactivation of Pt-based catalysts while enhancing their catalytic activity,selectivity,and durability remains a major challenge.Herein,we propose a strategy to enhance the CO tolerance of Pt clusters(Pt_n)by introducing neighboring functionalized vip single atoms(such as Fe,Co,Ni,Cu,Sb,and Bi).Among them,antimony(Sb)single atoms(SAs)exhibit significant performance enhancement,achieving 99%CO selectivity and 33.6%CO_(2)conversion at 450℃,Experimental results and density functional theory(DFT)calculations indicate the optimization arises from the electronic interaction between neighboring functionalized Sb SAs and Pt clusters,leading to optimal 5d electron redistribution in Pt clusters compared to other functionalized vip single atoms.The redistribution of 5d electrons weaken both theσdonation andπbackdonation interactions,resulting in a weakened bond strength with CO and enhancing catalyst activity and selectivity.In situ environmental transmission electron microscopy(ETEM)further demonstrates the exception thermal stability of the catalyst,even under H_(2)at 700℃.Notably,the functionalized Sb SAs also improve CO tolerance in various heterogenous catalysts,including Co/CeO_(2),Ni/CeO_(2),Pt/Al_(2)O_(3),and Pt/CeO_(2)-C.This finding provides an effective approach to overcome the primary challenge of CO poisoning in Pt-based catalysts,making their broader applications in various industrial catalysts.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602502)the National Natural Science Foundation of China(Grant No.12450404)。
文摘We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.
基金supported by the China National Postdoctoral Program for Innovative Talents(BX20200039)the Special Fund Project of“Mount Taishan Scholars”Construction Project in Shandong Province(ts20081130).
文摘A generalized multiple-mode prolate spherical wave functions (PSWFs) multi-carrier with index modulation approach is proposed with the purpose of improving the spectral efficiency of PSWFs multi-carrier systems. The proposed method,based on the optimized multi-index modulation, does not limit the number of signals in the first and second constellations and abandons the concept of limiting the number of signals in different constellations. It successfully increases the spectrum efficiency of the system while expanding the number of modulation symbol combinations and the index dimension of PSWFs signals. The proposed method outperforms the PSWFs multi-carrier index modulation method based on optimized multiple indexes in terms of spectrum efficiency, but at the expense of system computational complexity and bit error performance. For example, with n=10 subcarriers and a bit error rate of 1×10^(-5),spectral efficiency can be raised by roughly 12.4%.
基金supported by the National Key R&D Program of China(No.2023YFA1606701)the National Natural Science Foundation of China(Nos.12175042,11890710,11890714,12047514,12147101,and 12347106)+1 种基金Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030008)China National Key R&D Program(No.2022YFA1602402).
文摘We employed random distributions and gradient descent methods for the Generator Coordinate Method(GCM)to identify effective basis wave functions,taking halo nuclei ^(6)He and ^(6)Li as examples.By comparing the ground state(0^(+))energy of ^(6)He and the excited state(0^(+))energy of 6 Li calculated with various random distributions and manually selected generation coordinates,we found that the heavy tail characteristic of the logistic distribution better describes the features of the halo nuclei.Subsequently,the Adam algorithm from machine learning was applied to optimize the basis wave functions,indicating that a limited number of basis wave functions can approximate the converged values.These results offer some empirical insights for selecting basis wave functions and contribute to the broader application of machine learning methods in predicting effective basis wave functions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10775165 and 11104168)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2009AQ009)the National Basic Research Program of China(Grant No.2011CB808100)
文摘The motion and the energy of electrons driven by the ponderomotive force in linearly polarized high-intensity laser standing wave fields are considered. The results show that there exists a threshold laser intensity, above which the motion of electrons incident parallel to the electric field of the laser standing waves undergoes a transition from regulation to chaos. We propose that the huge energy exchange between the electrons and the strong laser standing waves is triggered by inelastic scattering, which is related to the chaos patterns. It is shown that an electron＇s energy gain of tens of MeV can be realized for a laser intensity of 10^20 W/cm^2.
基金funded by the Scientific Research Deanship at the University of Ha'il-Saudi Arabia through project number RG-23183.
文摘Nonplanar electron acoustic waves(NEAWs)with double spectral index-distributed hot electrons are studied under the two-temperature electrons model in a collisionless unmagnetized plasma.Using this model,the Korteweg–de Vries(KdV)equation is derived in nonplanar geometry.On the basis of the solutions of KdV equation,alterations of velocity,width,and amplitude of acoustic waves having various plasma factors are investigated.Nonlinear and dispersion coefficients obtained rely on double spectral index parameters r and q,and particle densityα.The combined influence of these factors significantly alters the features of electron acoustic waves in nonplanar geometry.This study is expected to contribute to the understanding of nonlinear principles that underlie nonplanar electrostatic waves in laboratory plasmas as well as in space.
基金supported by the National Natural Science Foundation of China(No.12172321)。
文摘The nonlinear traveling wave vibration of rotating ferromagnetic functionally graded(FG)cylindrical shells under multi-physics fields is investigated.Grounded in the Kirchhoff-Love thin shell theory,the geometric nonlinearity is incorporated into the model,and the constitutive equations are derived.The physical parameters of functionally graded materials(FGMs),which exhibit continuous variation across the thickness gradient,are of particular interest.The nonlinear magneto-thermoelastic governing equations are derived in accord with Hamilton's principle.The nonlinear partial differential equations are discretized with the Galerkin method,and the analytical expression of traveling wave frequencies is derived with an approximate method.The accuracy of the proposed method is validated through the comparison with the results from the literature and numerical solutions.Finally,the visualization analyses are conducted to examine the effects of key parameters on the traveling wave frequencies.The results show that the factors including the power-law index,temperature,magnetic field intensity,and rotating speed have the coupling effects with respect to the nonlinear vibration behavior.
文摘The nonlinear propagation of dust-acoustic (DA) shock waves in three-component unmagnetized dusty plasma consisting of nonextensive electrons, Maxwellian ions and arbitrarily charged mobile dust grain has been investigated. It is found that the presence of q-nonextensive electrons and ions can change the nonlinear behavior of shock wave. The standard reductive perturbation method is employed to study the basic features (phase speed, amplitude and width) of DA shock waves (DASWs) which are significantly modified by the presence of Maxwellian ions and nonextensive electrons. The present investigation can be very effective for understanding the nonlinear characteristics of the DASWs in space and laboratory dusty plasmas.
基金The project supported by National Natural Science Foundation of China under Grant No. 10575082
文摘In this paper, （2＋1）-dimensional electron acoustic waves （EAW） in an unmagnetized collisionless plasma have been studied by the linearized method and the reductive perturbation technique, respectively. The dispersion relation and a modified Kadomtsev-Petviashvili （KP） equation have been obtained for the EAW in the plasma considering a cold electron fluid and a vortex-like hot electrons. It is found from some numerical results that the parameter β（the ratio of the free hot electron temperature to the hot trapped electron temperature） effects on the amplitude and the Width of the electron acoustic solitary waves （EASW）. It can be indicated that the free hot electron temperature and the hot trapped electron temperature have very important effect on the characters of the propagation for the EASW.
基金supported by the National Natural Science Foundation of China(Nos.22275156,52025132,21,621,091,52300138,22021001 and 22121001)the Fundamental Research Funds for the Central Universities of China(No.20720220019)+2 种基金the National Science Foundation of Fujian Province of China(No.2022J02059)the 111 Project(Nos.B17027,B16029)the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘The development of next-generation electromagnetic wave(EMW)absorbers requires a shift in interface design.By employing hierarchical work function programming,we propose an approach to tune interfacial polarization dynamics.This method utilizes multi-gradient work functions to guide carrier migration and polarization effectively,thereby enhancing energy dissipation under alternating electromagnetic fields.Here,we constructed a 1T/2H-MoS_(2)/PPy/VS_(2) composite absorber with integrated gradient interfaces.The composite achieved a powerful absorption(RLmin)of-58.59 dB at 2.3 mm,and an effective absorption bandwidth(EAB)of 7.44 GHz at 2.5 mm,demonstrating improved broadband absorption.Radar cross-section(RCS)simulations show an EMW loss of-7.2 dB m^(2) at 0°,highlighting its potential for stealth and communication applications.This study introduces hierarchical work function programming as a promising strategy in EMW absorber design,contributing to advancements in material performance and functionality.
