The time of the energy emission between two neighbouring electron levels in the hydrogen atom has been calculated first on the basis of the quantum aspects of the Joule-Lenz law, next this time is approached with the ...The time of the energy emission between two neighbouring electron levels in the hydrogen atom has been calculated first on the basis of the quantum aspects of the Joule-Lenz law, next this time is approached with the aid of the electrodynamical parameters characteristic for the electron motion in the atom. Both methods indicate a similar result, namely that the time of emission is close to the time period of the electromagnetic wave produced in course of the emission. As a by-product of calculations, the formula representing the radius of the electron microparticle is obtained from a simple combination of the expressions for the Bohr magnetic moment and a quantum of the magnetic flux.展开更多
In the course of designing and developing different-purpose electrodynamical devices,electromagnetic processes in movable and immovable media need to be calculated simultaneously.The solution for such tasks based on t...In the course of designing and developing different-purpose electrodynamical devices,electromagnetic processes in movable and immovable media need to be calculated simultaneously.The solution for such tasks based on the electromagnetic field theory is associated with the emergence of significant theoretical and practical difficulties.The problems that arise during the calculation of electromagnetic processes in movable and immovable media of electrodynamical devices using the electromagnetic field theory are examined in this study.Improved approaches toward the calculation of electromagnetic processes in electrodynamical devices using Maxwell’s equations are suggested.Notably,calculating electromagnetic processes in movable and immovable media using Maxwell’s equations necessitates consideration of the systems of coordinates where the electromagnetic phenomena are analyzed.Theoretically substantiated methods of calculating electromagnetic processes in movable and immovable media based on the principles of electromagnetic field theory are proposed.The methods consider the systems of coordinates where the analysis of electromagnetic phenomena is conducted.The effectiveness of the suggested methods for example in calculating electromagnetic processes in movable and immovable media of the turbogenerator is illustrated.展开更多
Tunable plasmonic structures provide the possibility to actively modify the radiation from atoms through electromagnetic coupling.In this paper,we investigate the decay and radiation behavior of an atom near a dielect...Tunable plasmonic structures provide the possibility to actively modify the radiation from atoms through electromagnetic coupling.In this paper,we investigate the decay and radiation behavior of an atom near a dielectric nanosphere with conductive surface within the framework of macroscopic quantum electrodynamics.The electromagnetic fields including the losses in the materials can be taken as fundamental excitations which interact with the atom through a transition dipole.Both weak and strong coupling regimes have been investigated.The decay rate and the angle-dependent light intensities indeed strongly depend on the parameters of the system,i.e.,the position and orientation of the dipole,the geometric size,and the surface conductivity,providing the opportunity of artificial control over these quantities.Generalizing the formalism in this paper to other systems,like metamaterials,is straightforward,which we believe may pave a way for future active quantum nanophotonic devices.展开更多
Recent theoretical investigations into the excitation energies of the high-Z lithium isoelectronic sequence(Li-like)ions have revealed significant discrepancies[Eur.Phys.J.Plus 1371253(2022)],with deviations between t...Recent theoretical investigations into the excitation energies of the high-Z lithium isoelectronic sequence(Li-like)ions have revealed significant discrepancies[Eur.Phys.J.Plus 1371253(2022)],with deviations between the methods employed reaching up to∼40 eV for U^(89+).In this work,we address this issue through a comprehensive study of Lilike uranium(U^(89+)),calculating the lowest 35 levels of the 1s^(2)nl(n≤6)configurations.We employ two independent relativistic methods:the multiconfiguration Dirac–Hartree–Fock(MCDHF)method implemented in the GRASP2K code,and the relativistic configuration interaction(RCI)method within the Flexible Atomic Code(FAC).Our calculations resolve the discrepancies,achieving excellent mutual agreement and reducing deviations from experimental benchmarks to within∼2 eV.Furthermore,we identify the bottlenecks to achieving sub-eV accuracy for each method in the strong-field,high-Z regime.To the best of our knowledge,this is the most extensive dataset for this ion to date,including excitation energies,lifetimes,and radiative properties for allowed(E1)and forbidden(M1,E2,M2)transitions.Estimated uncertainties for most strong allowed and forbidden transitions remain below 1%and 2%,respectively,rendering this dataset valuable for applications in plasma spectroscopy.The dataset that supported the findings of this study is available in Science Data Bank at https://doi.org/10.57760/sciencedb.32492.展开更多
The algebraic reconstruction technique(ART),multiplicative algebraic reconstruction technique(MART),and simultaneous iterative reconstruction technique(SIRT)are computational methodologies extensively utilized within ...The algebraic reconstruction technique(ART),multiplicative algebraic reconstruction technique(MART),and simultaneous iterative reconstruction technique(SIRT)are computational methodologies extensively utilized within the field of computerized ionospheric tomography(CIT)to facilitate three-dimensional reconstruction of the ionospheric morphology.However,reconstruction accuracy elicits recurrent disputes over its practical application,and people usually attribute this issue to incomplete and uneven coverage of the measurements.The Thermosphere Ionosphere Electrodynamics General Circulation Model(TIEGCM)offers a reasonable physics-based ionospheric background and is widely utilized in ionospheric research.We use the TIEGCM simulations as the targeted ionosphere because the current measurements are far from able to realistically reproduce the ionosphere in detail.Optimized designations of satellite measurements are conducted to investigate the limiting performance of CIT methods in ionospheric reconstruction.Similar to common practice,electron density distributions from outputs of the International Reference Ionosphere(IRI)model are used as the iterative initial value in CIT applications.The outcomes suggest that despite data coverage,iterative initial conditions also play an essential role in ionospheric reconstruction.In particular,in the longitudinal sectors where the iterative initial height of the F2-layer peak electron density(hmF2)differs substantially from the background densities,none of the three CIT methods can reproduce the exact background profile.When hmF2 is close but the ionospheric F2-layer peak density(NmF2)is different between the targeted background and initial conditions,the MART performs better than the ART and SIRT,as evidenced by the correlation coefficients of MART being above 0.97 and those of ART and SIRT being below 0.85.In summary,this investigation reveals the potential uncertainties in traditional CIT reconstruction,particularly when realistic hmF2 or NmF2 values differ substantially from the initial CIT conditions.展开更多
If the singularity of the cosmic Big Bang is taken as the origin of the reference coordinate system,the surrounding vacuum in the initial moments of it would exhibit radially-outward right-handed spiral motion at ligh...If the singularity of the cosmic Big Bang is taken as the origin of the reference coordinate system,the surrounding vacuum in the initial moments of it would exhibit radially-outward right-handed spiral motion at light speed.Based on this spatial motion hypothesis,we derive a unified field equation and a set of Maxwell’s equations for vacuum SWs(Scalar Waves)generating a huge spiral force field that drives the energy to spiral inwardly and distort,leading to the formation of mass.Furthermore,they also uncover that mass is fundamentally an ultimate expression of energy,manifesting as the result of spiral motion of space at light speed.And then,we indirectly validate the theory that coherent light waves’collision generate SWs and subsequently mass through the experiment verifying the Breit-Wheeler process.The establishment of our theory offers a new analytical tool for the exploration of mass origin,the cosmic Big Bang,unified field theories.展开更多
Silicon carbide(core third-generation wide-bandgap semiconductor)nanowires have superior characteristics and vital engineering potential in microelectric and photonic devices operating in harsh high-temperature and st...Silicon carbide(core third-generation wide-bandgap semiconductor)nanowires have superior characteristics and vital engineering potential in microelectric and photonic devices operating in harsh high-temperature and strong-irradiation environments.Herein,the dense monocrystalline forest-like 4H-and 6H-SiC nanowires(intrinsically bound as a single crystal)are fabricated using the top–down peeling method.They exhibit broadband light emissions spanning the red–green–blue spectral region.The naturally formed microcavity encapsulating the SiC nanowires yields discrete and multimodal emission lines;the luminescence lifetimes decrease to the order of picoseconds owing to improved photon density of states in the microcavity by the quantum electrodynamic Purcell effect.The measured Purcell factor of 8.35 agrees well with the theoretical value of 8.6.The low-temperature luminescence and work functions show significant dependence on the nanowire polytype.The luminescence exhibits peculiar staircase-function enhancement when the temperature is elevated to 200 K,owing to suppression of nonradiative transition channels.展开更多
Standard perturbation theory is employed to calculate the mass shifts of the 2^(1)S_(0)-^(3)S_(1)and 2^(3)S_(1)-2^(3)P_(J)transitions for^(4,6,8)He.High-precision results are obtained for the mass shifts in the isotop...Standard perturbation theory is employed to calculate the mass shifts of the 2^(1)S_(0)-^(3)S_(1)and 2^(3)S_(1)-2^(3)P_(J)transitions for^(4,6,8)He.High-precision results are obtained for the mass shifts in the isotope pairs 6He-4He and 8He-4He,with uncertainties below 1 part per million(ppm).Our analysis provides a complete set of isotope-shift results and systematically examines their sensitivity to nuclear charge-radius differences.Once experimental measurements reach a precision comparable to that of the calculated mass shifts,the squared differences of nuclear charge radii can be determined with an accuracy of approximately 0.4%-0.6%,representing an order-of-magnitude improvement over current values.展开更多
The development of industry stimulates the advancement of modern approaches for optimizing welded structures.This study presents three technologies for the treatment of welded structures based on the use of pulsed ele...The development of industry stimulates the advancement of modern approaches for optimizing welded structures.This study presents three technologies for the treatment of welded structures based on the use of pulsed electromagnetic fields,plasma currents,electrodynamic forces,and their combined effects—an emerging direction in engineering practice aimed at improving the mechanical properties of metallic materials and welded joints.Treatment with a pulsed electromagnetic field(Tw PEMF)technology is introduced,which enables the optimization of the stress-strain state in welded structures made of non-ferromagnetic materials.The study investigates the stress-strain state of ring-shaped samples of welded joints made from AMg6 aluminum alloy(δ=1.0 mm),using electronic speckle interferometry,both with and without an additional conductive shield,after Tw PEMF.It was found that Tw PEMF reduces the displacement values by 2 and 4 times and decreases residual stresses by 50%and 80%,respectively,in samples without and with the shield.Also presented is an electrodynamic treatment(EDT)technology for butt-welded joints of AMg61(1561)aluminum alloy with a thickness of δ=3.0 mm during tungsten inert gas(TIG)welding,compared to EDT applied at room temperature.Based on mathematical modeling and experimental data,EDT during TIG welding contributes to the formation of an optimal residual stress-strain state of the welded joint.Additionally,a surface treatment technology for structural optimization based on pulsed barrier discharge(PBD),which generates low-temperature plasma on the treated metal surface—is presented.It was found that PBD increased the Vickers hardness of 25Kh GNMT structural steel by 20%(420–510 kg/mm~2)at depths up to 2 mm and promoted microstructural refinement of the metal.展开更多
A theoretical analysis regarding active vibration control of rotating machines with current-controlled electrodynamic actuators between machine feet and steel frame foundation and with velocity feedback of the machine...A theoretical analysis regarding active vibration control of rotating machines with current-controlled electrodynamic actuators between machine feet and steel frame foundation and with velocity feedback of the machine feet vibrations is presented.First,a generalized mathematical formulation is derived based on a state-space description which can be used for different kinds of models(1D,2D,and 3D models).It is shown that under special boundary conditions,the control parameters can be directly implemented into the stiffness and damping matrices of the system.Based on the generalized mathematical formulation,an example of a rotating machine—described by a 2D model—with journal bearings,flexible rotor,current-controlled electrodynamic actuators,steel frame foundation,and velocity feedback of the machine feet vibrations is presented where the effectiveness of the described active vibration control system is demonstrated.展开更多
We present a 3+1 formulation of the light modes in nonlinear electrodynamics described by Plebanski-type Lagrangians,which include post-Maxwellian,Born-Infeld,ModMax,and Heisenberg-Euler-Schwinger QED Lagrangians.In n...We present a 3+1 formulation of the light modes in nonlinear electrodynamics described by Plebanski-type Lagrangians,which include post-Maxwellian,Born-Infeld,ModMax,and Heisenberg-Euler-Schwinger QED Lagrangians.In nonlinear electrodynamics,strong electromagnetic fields modify the vacuum such that it acquires optical properties.Such a field-modified vacuum can possess electric permittivity,magnetic permeability,and a magneto-electric response,inducing novel phenomena such as vacuum birefringence.By exploiting the mathematical structures of Plebanski-type Lagrangians,we establish a streamlined procedure and explicit formulas to determine light modes,i.e.,refractive indices and polarization vectors for a given propagation direction.We also work out the light modes of the various Lagrangians for an arbitrarily strong magnetic field.The 3+1 formulation advanced in this paper has direct applications to the current vacuum birefringence research:terrestrial experiments using permanent magnets/ultra-intense lasers for the subcritical regime and astrophysical observation of X-rays from highly magnetized neutron stars for the near-critical and supercritical regimes.展开更多
The Dicke model,which describes the collective interaction between an ensemble of atoms and a single-mode photon field,serves as a fundamental framework for studying light-matter interactions and quantum electrodynami...The Dicke model,which describes the collective interaction between an ensemble of atoms and a single-mode photon field,serves as a fundamental framework for studying light-matter interactions and quantum electrodynamic phenomena.In this work,we investigate the manifestation of non-Hermitian effects in a generalized Dicke model,where two dissipative atom ensembles interact with a single-mode photon field.We explore the system in the semiclassical limit as a non-Hermitian Dicke model,revealing rich exceptional points(EPs)and diabolic points.Furthermore,we explore the quantum signature of EPs in the Hilbert space,relying on discrete photon numbers.The transition of photons from antibunching to bunching at steady state is unravelled.Our findings deepen the understanding of non-Hermitian physics in light-matter interaction,which is instructive for the design of advanced photonic devices.展开更多
We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-ly...We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.展开更多
The Landé g factors of Ba+are very important in high-precision measurement physics.The wave functions,energy levels,and Landég factors for the 6s ^(2)S_(1/2) and 5d 2D_(3/2,5/2) states of Ba+ions were calcul...The Landé g factors of Ba+are very important in high-precision measurement physics.The wave functions,energy levels,and Landég factors for the 6s ^(2)S_(1/2) and 5d 2D_(3/2,5/2) states of Ba+ions were calculated using the multi-configuration Dirac-Hartree-Fock method and the model-quantum electrodynamics(QED)method.The contributions of the electron correlation effects and QED effects were discussed in detail.The transition energies are in excellent agreement with the experimental results,with differences of approximately 5 cm^(−1).The presently calculated g factor of 2.0024905(16)for the 6S1/2 agrees very well with the available experimental and theoretical results,with a difference at a level of 10^(−6).For the 5D_(3/2,5/2) states,the present results of 0.7993961(126)and 1.2003942(190)agree with the experimental results of 0.7993278(3)[Phys.Rev.A 541199(1996)]and 1.20036739(14)[Phys.Rev.Lett.124193001(2020)]very well,with differences at the level of 10−5.展开更多
We propose an all-optical,single-laser-pulse scheme for generating a dense relativistic strongly magnetized electron-positron pair plasma.The scheme involves the interaction of an extremely intense(I■10^(24) W/cm^(2)...We propose an all-optical,single-laser-pulse scheme for generating a dense relativistic strongly magnetized electron-positron pair plasma.The scheme involves the interaction of an extremely intense(I■10^(24) W/cm^(2))circularly polarized laser pulse with a solid-density target containing a conical cavity.Through full-scale three-dimensional particle-in-cell simulations that account for quantum electrodynamic effects,it is shown that this interaction results in two significant outcomes:first,the generation of quasi-static magnetic fields reaching tens of gigagauss,and,second,the production of large quantities of electron-positron pairs(up to 10^(13))via the Breit-Wheeler process.The e^(-)e^(+)plasma becomes trapped in the magnetic field and remains confined in a small volume for hundreds of femtoseconds,far exceeding the laser timescale.The dependence of pair plasma parameters,as well as the efficiency of plasma production and confinement,is discussed in relation to the properties of the laser pulse and the target.Realizing this scheme experimentally would enable the investigation of physical processes relevant to extreme astrophysical environments.展开更多
For the observed line at 799.23°A in tungsten EBIT experiment,which was assigned to be^(3)F_(4)^(o)−^(3)F_(3)^(o)([Ar]4s^(2)4p^(5)4d)of W^(38+)ion,there were noticeable deviations for most calculated wavelengths ...For the observed line at 799.23°A in tungsten EBIT experiment,which was assigned to be^(3)F_(4)^(o)−^(3)F_(3)^(o)([Ar]4s^(2)4p^(5)4d)of W^(38+)ion,there were noticeable deviations for most calculated wavelengths from the measured value.To clarify this issue,we carry out an extensive calculation for energy levels and transition properties of W^(38+)ion using the multi-configuration Dirac–Hartree–Fock and relativistic configuration interaction method,in which more deeper inner core electron correlations are included,and different forms of Breit interaction as well as quantum electrodynamics corrections are investigated.It is found that the inner core electron correlations can affect the total energy of levels,while only slightly modify the excited energy of levels in 4s^(2)4p^(5)4d complex.The present calculated wavelengths agree with the corresponding measured values excellently except the line at 799.23Å.Thus we are strongly suspicious this line should be misidentified,and suggest that new experiment with higher resolution and spectra analysis based on more accurate atomic data should be performed for W^(38+)ion.展开更多
Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger（D-S） equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies...Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger（D-S） equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies show that condensation and the value of fermion mass depends heavily on how the D-S equations are truncated.By solving a set of coupled D-S equations,it is also found that the fermion propagator shows a clear dependence on the order parameter.The truncated D-S equations under unquenched approximation are used to study the mass-function and chiral condensation of the fermions.The results under the unquenched approximation are clearly different from the ones under quenched approximation.With the increase in the order parameter,the fermion condensation in the unquenched approximation decreases when 0≤ξ5,while it increases when ξ5.However,nothing like this is observed in the quenched approximation,which indicates that there may be flaws in the quenched approximations.展开更多
Electrodynamics of the one-electron currents due to the circular orbital motion of the electron particle in the hydrogen atom has been examined. The motion is assumed to be induced by the time change of the magnetic f...Electrodynamics of the one-electron currents due to the circular orbital motion of the electron particle in the hydrogen atom has been examined. The motion is assumed to be induced by the time change of the magnetic field in the atom. A characteristic point is that the electric resistance calculated for the motion is independent of the orbit index and its size is similar to that obtained earlier experimentally for the planar free-electron-like structures considered in the integer quantum Hall effect. Other current parameters like conductivity and the relaxation time behave in a way similar to that being typical for metals. A special attention was attached to the relations between the current intensity and magnetic field. A correct reproduction of this field with the aid of the Biot-Savart law became possible when the geometrical microstructure of the electron particle has been explicitly taken into account. But the same microstructure properties do influence also the current velocity. In fact the current suitable for the Biot-Savart law should have a speed characteristic for a spinning electron particle and not that of a spinless electron circulating along the orbit of the original Bohr model.展开更多
Multipaction,caused by the secondary electron emission phenomenon,has been a challenge in space applications due to the resulting degradation of system performance as well as the reduction in the service life of high ...Multipaction,caused by the secondary electron emission phenomenon,has been a challenge in space applications due to the resulting degradation of system performance as well as the reduction in the service life of high power components.In this paper we report a novel approach to realize an effective increase in the multipaction threshold by employing micro-porous surfaces.Two micro-porous structures,i.e.,a regular micro-porous array fabricated by photolithography pattern processing and an irregular micro-porous array fabricated by a direct chemical etching technique,are proposed for suppressing the secondary electron yield（SEY） and multipaction in components,and the benefits are validated both theoretically and experimentally.These surface processing technologies are compatible with the metal plating process,and offer substantial flexibility and accuracy in topology design.The suppression effect is quantified for the first time through the proper fitting of the surface morphology and the corresponding secondary emission properties.Insertion losses when using these structures decrease dramatically compared with regular millimeter-scale structures on high power dielectric windows.SEY tests on samples show that the maximum yield of Ag-plated samples is reduced from 2.17 to 1.58 for directly chemical etched samples.Multipaction testing of actual C-band impedance transformers shows that the discharge thresholds of the processed components increase from 2100 W to 5500 W for photolithography pattern processing and 7200 W for direct chemical etching,respectively.Insertion losses increase from 0.13 d B to only 0.15 d B for both surface treatments in the transmission band.The experimental results agree well with the simulation results,which offers great potential in the quantitative anti-multipaction design of high power microwave components for space applications.展开更多
This paper briefly reviews ionospheric irregularities that occur in the E and F regions at mid-latitudes. Sporadic E(ES) is a common ionospheric irregularity phenomenon that is first noticed in the E layer. ES mainly ...This paper briefly reviews ionospheric irregularities that occur in the E and F regions at mid-latitudes. Sporadic E(ES) is a common ionospheric irregularity phenomenon that is first noticed in the E layer. ES mainly appears during daytime in summer hemispheres, and is formed primarily from neutral wind shear in the mesosphere and lower thermosphere(MLT) region. Field-aligned irregularity(FAI) in the E region is also observed by Very High Frequency(VHF) radar in mid-latitude regions. FAI frequently occurs after sunset in summer hemispheres, and spectrum features of E region FAI echoes suggest that type-2 irregularity is dominant in the nighttime ionosphere. A close relationship between ES and E region FAI implies that ES may be a possible source of E region FAI in the nighttime ionosphere. Strong neutral wind shear, steep ES plasma density gradient, and a polarized electric field are the significant factors affecting the formation of E region FAI. At mid-latitudes, joint observational experiments including ionosonde, VHF radar, Global Positioning System(GPS) stations, and all-sky optical images have revealed strong connections across different scales of ionospheric irregularities in the nighttime F region, such as spread F(SF), medium-scale traveling ionospheric disturbances(MSTID), and F region FAI.Observations suggest that different scales of ionospheric irregularities are generally attributed to the Perkins instability and subsequently excited gradient drift instability. Nighttime MSTID can further evolve into small-scale structures through a nonlinear cascade process when a steep plasma density gradient exists at the bottom of the F region. In addition, the effect of ionospheric electrodynamic coupling processes, including ionospheric E-F coupling and inter-hemispheric coupling on the generation of ionospheric irregularities, becomes more prominent due to the significant dip angle and equipotentiality of magnetic field lines in the mid-latitude ionosphere. Polarized electric fields can map to different ionospheric regions and excite plasma instabilities which form ionospheric irregularities. Nevertheless,the mapping efficiency of a polarized electric field depends on the ionospheric background and spatial scale of the field.展开更多
文摘The time of the energy emission between two neighbouring electron levels in the hydrogen atom has been calculated first on the basis of the quantum aspects of the Joule-Lenz law, next this time is approached with the aid of the electrodynamical parameters characteristic for the electron motion in the atom. Both methods indicate a similar result, namely that the time of emission is close to the time period of the electromagnetic wave produced in course of the emission. As a by-product of calculations, the formula representing the radius of the electron microparticle is obtained from a simple combination of the expressions for the Bohr magnetic moment and a quantum of the magnetic flux.
文摘In the course of designing and developing different-purpose electrodynamical devices,electromagnetic processes in movable and immovable media need to be calculated simultaneously.The solution for such tasks based on the electromagnetic field theory is associated with the emergence of significant theoretical and practical difficulties.The problems that arise during the calculation of electromagnetic processes in movable and immovable media of electrodynamical devices using the electromagnetic field theory are examined in this study.Improved approaches toward the calculation of electromagnetic processes in electrodynamical devices using Maxwell’s equations are suggested.Notably,calculating electromagnetic processes in movable and immovable media using Maxwell’s equations necessitates consideration of the systems of coordinates where the electromagnetic phenomena are analyzed.Theoretically substantiated methods of calculating electromagnetic processes in movable and immovable media based on the principles of electromagnetic field theory are proposed.The methods consider the systems of coordinates where the analysis of electromagnetic phenomena is conducted.The effectiveness of the suggested methods for example in calculating electromagnetic processes in movable and immovable media of the turbogenerator is illustrated.
基金supported by Hangzhou Dianzi University(Grant No.KYS075621018)supported by the Natural Science Foundation of Zhejiang Province(Grant No.LY24A050004)。
文摘Tunable plasmonic structures provide the possibility to actively modify the radiation from atoms through electromagnetic coupling.In this paper,we investigate the decay and radiation behavior of an atom near a dielectric nanosphere with conductive surface within the framework of macroscopic quantum electrodynamics.The electromagnetic fields including the losses in the materials can be taken as fundamental excitations which interact with the atom through a transition dipole.Both weak and strong coupling regimes have been investigated.The decay rate and the angle-dependent light intensities indeed strongly depend on the parameters of the system,i.e.,the position and orientation of the dipole,the geometric size,and the surface conductivity,providing the opportunity of artificial control over these quantities.Generalizing the formalism in this paper to other systems,like metamaterials,is straightforward,which we believe may pave a way for future active quantum nanophotonic devices.
基金supported by the Research Foundation for Higher Level Talents of West Anhui University(Grant No.WGKQ2021005)the Research Projects of West An-hui University(Grant No.WXZR202418).
文摘Recent theoretical investigations into the excitation energies of the high-Z lithium isoelectronic sequence(Li-like)ions have revealed significant discrepancies[Eur.Phys.J.Plus 1371253(2022)],with deviations between the methods employed reaching up to∼40 eV for U^(89+).In this work,we address this issue through a comprehensive study of Lilike uranium(U^(89+)),calculating the lowest 35 levels of the 1s^(2)nl(n≤6)configurations.We employ two independent relativistic methods:the multiconfiguration Dirac–Hartree–Fock(MCDHF)method implemented in the GRASP2K code,and the relativistic configuration interaction(RCI)method within the Flexible Atomic Code(FAC).Our calculations resolve the discrepancies,achieving excellent mutual agreement and reducing deviations from experimental benchmarks to within∼2 eV.Furthermore,we identify the bottlenecks to achieving sub-eV accuracy for each method in the strong-field,high-Z regime.To the best of our knowledge,this is the most extensive dataset for this ion to date,including excitation energies,lifetimes,and radiative properties for allowed(E1)and forbidden(M1,E2,M2)transitions.Estimated uncertainties for most strong allowed and forbidden transitions remain below 1%and 2%,respectively,rendering this dataset valuable for applications in plasma spectroscopy.The dataset that supported the findings of this study is available in Science Data Bank at https://doi.org/10.57760/sciencedb.32492.
基金supported by the National Key R&D Program of China (Grant No. 2022YFF0503702)the National Natural Science Foundation of China (Grant No. 42074186)
文摘The algebraic reconstruction technique(ART),multiplicative algebraic reconstruction technique(MART),and simultaneous iterative reconstruction technique(SIRT)are computational methodologies extensively utilized within the field of computerized ionospheric tomography(CIT)to facilitate three-dimensional reconstruction of the ionospheric morphology.However,reconstruction accuracy elicits recurrent disputes over its practical application,and people usually attribute this issue to incomplete and uneven coverage of the measurements.The Thermosphere Ionosphere Electrodynamics General Circulation Model(TIEGCM)offers a reasonable physics-based ionospheric background and is widely utilized in ionospheric research.We use the TIEGCM simulations as the targeted ionosphere because the current measurements are far from able to realistically reproduce the ionosphere in detail.Optimized designations of satellite measurements are conducted to investigate the limiting performance of CIT methods in ionospheric reconstruction.Similar to common practice,electron density distributions from outputs of the International Reference Ionosphere(IRI)model are used as the iterative initial value in CIT applications.The outcomes suggest that despite data coverage,iterative initial conditions also play an essential role in ionospheric reconstruction.In particular,in the longitudinal sectors where the iterative initial height of the F2-layer peak electron density(hmF2)differs substantially from the background densities,none of the three CIT methods can reproduce the exact background profile.When hmF2 is close but the ionospheric F2-layer peak density(NmF2)is different between the targeted background and initial conditions,the MART performs better than the ART and SIRT,as evidenced by the correlation coefficients of MART being above 0.97 and those of ART and SIRT being below 0.85.In summary,this investigation reveals the potential uncertainties in traditional CIT reconstruction,particularly when realistic hmF2 or NmF2 values differ substantially from the initial CIT conditions.
文摘If the singularity of the cosmic Big Bang is taken as the origin of the reference coordinate system,the surrounding vacuum in the initial moments of it would exhibit radially-outward right-handed spiral motion at light speed.Based on this spatial motion hypothesis,we derive a unified field equation and a set of Maxwell’s equations for vacuum SWs(Scalar Waves)generating a huge spiral force field that drives the energy to spiral inwardly and distort,leading to the formation of mass.Furthermore,they also uncover that mass is fundamentally an ultimate expression of energy,manifesting as the result of spiral motion of space at light speed.And then,we indirectly validate the theory that coherent light waves’collision generate SWs and subsequently mass through the experiment verifying the Breit-Wheeler process.The establishment of our theory offers a new analytical tool for the exploration of mass origin,the cosmic Big Bang,unified field theories.
基金supported by the National Natural Science Foundation of China(Grant No.12274076).
文摘Silicon carbide(core third-generation wide-bandgap semiconductor)nanowires have superior characteristics and vital engineering potential in microelectric and photonic devices operating in harsh high-temperature and strong-irradiation environments.Herein,the dense monocrystalline forest-like 4H-and 6H-SiC nanowires(intrinsically bound as a single crystal)are fabricated using the top–down peeling method.They exhibit broadband light emissions spanning the red–green–blue spectral region.The naturally formed microcavity encapsulating the SiC nanowires yields discrete and multimodal emission lines;the luminescence lifetimes decrease to the order of picoseconds owing to improved photon density of states in the microcavity by the quantum electrodynamic Purcell effect.The measured Purcell factor of 8.35 agrees well with the theoretical value of 8.6.The low-temperature luminescence and work functions show significant dependence on the nanowire polytype.The luminescence exhibits peculiar staircase-function enhancement when the temperature is elevated to 200 K,owing to suppression of nonradiative transition channels.
基金supported by the National Natural Science Foundation of China(Grant Nos.12204412,12274423,12174402,12393821,and 12004124)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB0920100 and XDB0920101)support from the Natural Sciences and Engineering Research Council of Canada.All calculations were performed on the APM-Theoretical Computing Cluster(APM-TCC).
文摘Standard perturbation theory is employed to calculate the mass shifts of the 2^(1)S_(0)-^(3)S_(1)and 2^(3)S_(1)-2^(3)P_(J)transitions for^(4,6,8)He.High-precision results are obtained for the mass shifts in the isotope pairs 6He-4He and 8He-4He,with uncertainties below 1 part per million(ppm).Our analysis provides a complete set of isotope-shift results and systematically examines their sensitivity to nuclear charge-radius differences.Once experimental measurements reach a precision comparable to that of the calculated mass shifts,the squared differences of nuclear charge radii can be determined with an accuracy of approximately 0.4%-0.6%,representing an order-of-magnitude improvement over current values.
文摘The development of industry stimulates the advancement of modern approaches for optimizing welded structures.This study presents three technologies for the treatment of welded structures based on the use of pulsed electromagnetic fields,plasma currents,electrodynamic forces,and their combined effects—an emerging direction in engineering practice aimed at improving the mechanical properties of metallic materials and welded joints.Treatment with a pulsed electromagnetic field(Tw PEMF)technology is introduced,which enables the optimization of the stress-strain state in welded structures made of non-ferromagnetic materials.The study investigates the stress-strain state of ring-shaped samples of welded joints made from AMg6 aluminum alloy(δ=1.0 mm),using electronic speckle interferometry,both with and without an additional conductive shield,after Tw PEMF.It was found that Tw PEMF reduces the displacement values by 2 and 4 times and decreases residual stresses by 50%and 80%,respectively,in samples without and with the shield.Also presented is an electrodynamic treatment(EDT)technology for butt-welded joints of AMg61(1561)aluminum alloy with a thickness of δ=3.0 mm during tungsten inert gas(TIG)welding,compared to EDT applied at room temperature.Based on mathematical modeling and experimental data,EDT during TIG welding contributes to the formation of an optimal residual stress-strain state of the welded joint.Additionally,a surface treatment technology for structural optimization based on pulsed barrier discharge(PBD),which generates low-temperature plasma on the treated metal surface—is presented.It was found that PBD increased the Vickers hardness of 25Kh GNMT structural steel by 20%(420–510 kg/mm~2)at depths up to 2 mm and promoted microstructural refinement of the metal.
文摘A theoretical analysis regarding active vibration control of rotating machines with current-controlled electrodynamic actuators between machine feet and steel frame foundation and with velocity feedback of the machine feet vibrations is presented.First,a generalized mathematical formulation is derived based on a state-space description which can be used for different kinds of models(1D,2D,and 3D models).It is shown that under special boundary conditions,the control parameters can be directly implemented into the stiffness and damping matrices of the system.Based on the generalized mathematical formulation,an example of a rotating machine—described by a 2D model—with journal bearings,flexible rotor,current-controlled electrodynamic actuators,steel frame foundation,and velocity feedback of the machine feet vibrations is presented where the effectiveness of the described active vibration control system is demonstrated.
基金supported by the Ultrashort Quantum Beam Facility operation program(Grant No.140011)through APRI,GISTalso by the Institute of Basic Science(Grant No.IBSR038-D1).
文摘We present a 3+1 formulation of the light modes in nonlinear electrodynamics described by Plebanski-type Lagrangians,which include post-Maxwellian,Born-Infeld,ModMax,and Heisenberg-Euler-Schwinger QED Lagrangians.In nonlinear electrodynamics,strong electromagnetic fields modify the vacuum such that it acquires optical properties.Such a field-modified vacuum can possess electric permittivity,magnetic permeability,and a magneto-electric response,inducing novel phenomena such as vacuum birefringence.By exploiting the mathematical structures of Plebanski-type Lagrangians,we establish a streamlined procedure and explicit formulas to determine light modes,i.e.,refractive indices and polarization vectors for a given propagation direction.We also work out the light modes of the various Lagrangians for an arbitrarily strong magnetic field.The 3+1 formulation advanced in this paper has direct applications to the current vacuum birefringence research:terrestrial experiments using permanent magnets/ultra-intense lasers for the subcritical regime and astrophysical observation of X-rays from highly magnetized neutron stars for the near-critical and supercritical regimes.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1404400)the National Natural Science Foundation of China(Grant Nos.12125504 and 12305050)+3 种基金Zhejiang Provincial Natural Science Foundation(Grant No.LZ25A050001)the Doctoral Support Program for Young Talents of the China Association for Science and Technologythe Hundred Talents Program of the Chinese Academy of Sciencesthe Natural Science Foundation of Jiangsu Higher Education Institutions of China(Grant No.23KJB140017)。
文摘The Dicke model,which describes the collective interaction between an ensemble of atoms and a single-mode photon field,serves as a fundamental framework for studying light-matter interactions and quantum electrodynamic phenomena.In this work,we investigate the manifestation of non-Hermitian effects in a generalized Dicke model,where two dissipative atom ensembles interact with a single-mode photon field.We explore the system in the semiclassical limit as a non-Hermitian Dicke model,revealing rich exceptional points(EPs)and diabolic points.Furthermore,we explore the quantum signature of EPs in the Hilbert space,relying on discrete photon numbers.The transition of photons from antibunching to bunching at steady state is unravelled.Our findings deepen the understanding of non-Hermitian physics in light-matter interaction,which is instructive for the design of advanced photonic devices.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602501)the National Natural Science Foundation of China(Grant No.12011530060)+1 种基金supported solely by the Russian Science Foundation(Grant No.22-12-00043)supported by the Chinese Academy of Sciences(CAS)Presidents International Fellowship Initiative(PIFI)(Grant Nos.2018VMB0016 and 2022VMC0002),respectively。
文摘We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.
基金supported by the National key Research and Development Program of China under Grant No.2022YFA1602500the National Natural Science Foundation of China under Grant Nos.12174316 and 1236040286,and 12404306。
文摘The Landé g factors of Ba+are very important in high-precision measurement physics.The wave functions,energy levels,and Landég factors for the 6s ^(2)S_(1/2) and 5d 2D_(3/2,5/2) states of Ba+ions were calculated using the multi-configuration Dirac-Hartree-Fock method and the model-quantum electrodynamics(QED)method.The contributions of the electron correlation effects and QED effects were discussed in detail.The transition energies are in excellent agreement with the experimental results,with differences of approximately 5 cm^(−1).The presently calculated g factor of 2.0024905(16)for the 6S1/2 agrees very well with the available experimental and theoretical results,with a difference at a level of 10^(−6).For the 5D_(3/2,5/2) states,the present results of 0.7993961(126)and 1.2003942(190)agree with the experimental results of 0.7993278(3)[Phys.Rev.A 541199(1996)]and 1.20036739(14)[Phys.Rev.Lett.124193001(2020)]very well,with differences at the level of 10−5.
基金supported by BMBF-Project No.05P24PF1DFG Project No.PU 213/6-3.
文摘We propose an all-optical,single-laser-pulse scheme for generating a dense relativistic strongly magnetized electron-positron pair plasma.The scheme involves the interaction of an extremely intense(I■10^(24) W/cm^(2))circularly polarized laser pulse with a solid-density target containing a conical cavity.Through full-scale three-dimensional particle-in-cell simulations that account for quantum electrodynamic effects,it is shown that this interaction results in two significant outcomes:first,the generation of quasi-static magnetic fields reaching tens of gigagauss,and,second,the production of large quantities of electron-positron pairs(up to 10^(13))via the Breit-Wheeler process.The e^(-)e^(+)plasma becomes trapped in the magnetic field and remains confined in a small volume for hundreds of femtoseconds,far exceeding the laser timescale.The dependence of pair plasma parameters,as well as the efficiency of plasma production and confinement,is discussed in relation to the properties of the laser pulse and the target.Realizing this scheme experimentally would enable the investigation of physical processes relevant to extreme astrophysical environments.
基金supported by the Science Challenge Project of China Academy of Engineering Physics(CAEP)(Grant No.TZ2018005)the National Natural Science Foundation of China(Grant Nos.12474277,12374259,12104095,12074081,and 12074082).
文摘For the observed line at 799.23°A in tungsten EBIT experiment,which was assigned to be^(3)F_(4)^(o)−^(3)F_(3)^(o)([Ar]4s^(2)4p^(5)4d)of W^(38+)ion,there were noticeable deviations for most calculated wavelengths from the measured value.To clarify this issue,we carry out an extensive calculation for energy levels and transition properties of W^(38+)ion using the multi-configuration Dirac–Hartree–Fock and relativistic configuration interaction method,in which more deeper inner core electron correlations are included,and different forms of Breit interaction as well as quantum electrodynamics corrections are investigated.It is found that the inner core electron correlations can affect the total energy of levels,while only slightly modify the excited energy of levels in 4s^(2)4p^(5)4d complex.The present calculated wavelengths agree with the corresponding measured values excellently except the line at 799.23Å.Thus we are strongly suspicious this line should be misidentified,and suggest that new experiment with higher resolution and spectra analysis based on more accurate atomic data should be performed for W^(38+)ion.
基金The Science Foundation of Southeast University,the National Natural Science Foundation of China (No. 11047005)
文摘Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger（D-S） equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies show that condensation and the value of fermion mass depends heavily on how the D-S equations are truncated.By solving a set of coupled D-S equations,it is also found that the fermion propagator shows a clear dependence on the order parameter.The truncated D-S equations under unquenched approximation are used to study the mass-function and chiral condensation of the fermions.The results under the unquenched approximation are clearly different from the ones under quenched approximation.With the increase in the order parameter,the fermion condensation in the unquenched approximation decreases when 0≤ξ5,while it increases when ξ5.However,nothing like this is observed in the quenched approximation,which indicates that there may be flaws in the quenched approximations.
文摘Electrodynamics of the one-electron currents due to the circular orbital motion of the electron particle in the hydrogen atom has been examined. The motion is assumed to be induced by the time change of the magnetic field in the atom. A characteristic point is that the electric resistance calculated for the motion is independent of the orbit index and its size is similar to that obtained earlier experimentally for the planar free-electron-like structures considered in the integer quantum Hall effect. Other current parameters like conductivity and the relaxation time behave in a way similar to that being typical for metals. A special attention was attached to the relations between the current intensity and magnetic field. A correct reproduction of this field with the aid of the Biot-Savart law became possible when the geometrical microstructure of the electron particle has been explicitly taken into account. But the same microstructure properties do influence also the current velocity. In fact the current suitable for the Biot-Savart law should have a speed characteristic for a spinning electron particle and not that of a spinless electron circulating along the orbit of the original Bohr model.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1537211)the National Key Laboratory Key Foundation,China(Grant No.9140C530101150C53011)China Postdoctoral Science Foundation(Grant No.2015M572661XB)
文摘Multipaction,caused by the secondary electron emission phenomenon,has been a challenge in space applications due to the resulting degradation of system performance as well as the reduction in the service life of high power components.In this paper we report a novel approach to realize an effective increase in the multipaction threshold by employing micro-porous surfaces.Two micro-porous structures,i.e.,a regular micro-porous array fabricated by photolithography pattern processing and an irregular micro-porous array fabricated by a direct chemical etching technique,are proposed for suppressing the secondary electron yield（SEY） and multipaction in components,and the benefits are validated both theoretically and experimentally.These surface processing technologies are compatible with the metal plating process,and offer substantial flexibility and accuracy in topology design.The suppression effect is quantified for the first time through the proper fitting of the surface morphology and the corresponding secondary emission properties.Insertion losses when using these structures decrease dramatically compared with regular millimeter-scale structures on high power dielectric windows.SEY tests on samples show that the maximum yield of Ag-plated samples is reduced from 2.17 to 1.58 for directly chemical etched samples.Multipaction testing of actual C-band impedance transformers shows that the discharge thresholds of the processed components increase from 2100 W to 5500 W for photolithography pattern processing and 7200 W for direct chemical etching,respectively.Insertion losses increase from 0.13 d B to only 0.15 d B for both surface treatments in the transmission band.The experimental results agree well with the simulation results,which offers great potential in the quantitative anti-multipaction design of high power microwave components for space applications.
基金supported by the National Natural Science Foundation of China (No. 41574146, 41774162, 42074187)the National Key R&D Program of China (No. 2018YFC1503506)+1 种基金the Excellent Youth Foundation of Hubei Provincial Natural Science Foundation (No. 2019CFA054)the Foundation of the National Key Laboratory of Electromagnetic Environment (No. 20200101)。
文摘This paper briefly reviews ionospheric irregularities that occur in the E and F regions at mid-latitudes. Sporadic E(ES) is a common ionospheric irregularity phenomenon that is first noticed in the E layer. ES mainly appears during daytime in summer hemispheres, and is formed primarily from neutral wind shear in the mesosphere and lower thermosphere(MLT) region. Field-aligned irregularity(FAI) in the E region is also observed by Very High Frequency(VHF) radar in mid-latitude regions. FAI frequently occurs after sunset in summer hemispheres, and spectrum features of E region FAI echoes suggest that type-2 irregularity is dominant in the nighttime ionosphere. A close relationship between ES and E region FAI implies that ES may be a possible source of E region FAI in the nighttime ionosphere. Strong neutral wind shear, steep ES plasma density gradient, and a polarized electric field are the significant factors affecting the formation of E region FAI. At mid-latitudes, joint observational experiments including ionosonde, VHF radar, Global Positioning System(GPS) stations, and all-sky optical images have revealed strong connections across different scales of ionospheric irregularities in the nighttime F region, such as spread F(SF), medium-scale traveling ionospheric disturbances(MSTID), and F region FAI.Observations suggest that different scales of ionospheric irregularities are generally attributed to the Perkins instability and subsequently excited gradient drift instability. Nighttime MSTID can further evolve into small-scale structures through a nonlinear cascade process when a steep plasma density gradient exists at the bottom of the F region. In addition, the effect of ionospheric electrodynamic coupling processes, including ionospheric E-F coupling and inter-hemispheric coupling on the generation of ionospheric irregularities, becomes more prominent due to the significant dip angle and equipotentiality of magnetic field lines in the mid-latitude ionosphere. Polarized electric fields can map to different ionospheric regions and excite plasma instabilities which form ionospheric irregularities. Nevertheless,the mapping efficiency of a polarized electric field depends on the ionospheric background and spatial scale of the field.
