Electrodynamics of solar wind-magnetosphere-ionosphere interactions

The authors present a coherent picture of fundamental physical processes in three basic elements of the SW-I (solar wind-magnetosphere-ionosphere) coupling system: (i) the field-aligned potential structure which leads to the formation of auroral arcs; (ii) the magnetosphere coupling which leads to the onset of magnetospheric substorms; and (iii) the solar wind-magnetosphere dynamo which supplies the power for driving various magnetospheric processes. The field-aligned potential structure on auroral lines is forced into existence by the loss-cone constriction effect when the upward field-aligned current density exceeds the loss-cone thermal flux limit. The substorm onset occurs when the ionosphere responds fully to the enhanced magnetospheric convection driven by the solar wind. The energy is transferred from the solar wind to the magnetosphere by a dynamo process primarily on open field lines     

我国磁层物理研究进展

我国磁层物理是在赵九章倡导下从１９５９年开始发展起来的,４０多年来,我国磁层物理有了很大进展。文章对我国磁层物理研究的主要成果作了概述,主要内容包括：磁层顶边界层的瞬时重联研究,磁层顶的不稳定性和反常输产业暴过程研究,磁尾动力学过程研究,极光加速区非线性波和粒子加速研究,行星磁了后是磁层物理发展趋势的展望。     

The role of O+ ions in channeling solar wind energy tothe ionosphere

In space weather prediction, the transport of solar wind energy through the magnetosphere is a major aspect. For the transport of energy from the magnetosphere to the ionosphere, magnetic field-aligned (Birkeland) currents are a very important agent. The authors discuss the role of O⁺ ions for driving field-aligned currents of spatially alternating polarity that may explain multiple auroral arcs. It is known from earlier work that nonadiabatic motion of O⁺ ions in the magnetotail plasma can lead to the formation of density striations that are stationary in the GSM frame. As the magnetospheric plasma drifts through these density striations, magnetic field-aligned currents of alternating signs are forced to flow in and out of the oxygen-rich region to maintain quasineutrality. This generates Alfven waves that propagate in the drifting plasma but can form stationary structures in the GSM frame. As the currents close in the ionosphere, the equatorial plasma constitutes a generator from which spatially alternating magnetic field-aligned currents carry energy to the ionospheric load. The wavelength of the density striations, mapped to the ionosphere, is compatible with the spacing of stable auroral arcs, and the power supplied by the equatorial generator region is estimated to be compatible with what is needed to drive auroral arcs. Thus, the consequences of nonadiabatic motion of O⁺ ions may explain how part of the energy extracted from the solar wind is channelled into multiple auroral arcs     

The Three Dimensional Non-conforming Finite Element Solution of the Chapman–Ferraro Problem

We demonstrate the feasibility of using a non-conforming, piecewise harmonic finite element method on an unstructured grid in solving a magnetospheric physics problem. We use this approach to construct a global discrete model of the magnetic field of the magnetosphere that includes the effects of shielding currents at the outer boundary (the magnetopause). As in the approach of F. R. Toffolettoet al.(1994,Geophys. Res. Lett.21, 7) the internal magnetospheric field model is that of R. V. Hilmer and G.-H. Voigt (1995,J. Geophys. Res.) while the magnetopause shape is based on an empirically determined approximation (1997, J. Shueet al.,J. Geophys. Res.102, 9497). The results is a magnetic field model whose field lines are completely confined within the magnetosphere. The presented numerical results indicate that the discrete non-conforming finite element model is well-suited for magnetospheric field modeling.     

VALIS: A split-conservative scheme for the relativistic 2D Vlasov–Maxwell system

An accurate treatment of the relativistic Vlasov–Maxwell system is of fundamental importance to a broad range of plasma physics topics, including laser–plasma interaction, transport in solar and magnetospheric plasmas and magnetically confined plasmas. This paper introduces VALIS: an algorithm for the numerical solution of the Vlasov–Maxwell system in two spatial dimensions and two momentum dimensions.     

Der Einfluß einer Krümmung auf eine wandstabilisierte Lichtbogenentladung

In this paper the analysis of gas heating phenomena in wallstabilized toroidal electric arcs is derived and the results are applied to a nitrogen arc at a pressure of one atmosphere. These investigations have been performed on the basis of the single-fluid model of plasma physics taking into consideration the thermal properties of the wall material. By using a differential method it is outlined how the equation of energy is solved not only in the arc but also in the wall.     

Zur numerischen Beschreibung rotationssymmetrischer wandstabilisierter Lichtbogenkonfigurationen

A method is outlined which gives a numerical describtion for some configurations of axially symmetrical constricted electric arcs. For this purpose the equations of single fluid model of plasma physics are decoupled in such a way that only the heat flux potential, the axial velocity, the radial velocity, the average axial pressure gradient, and the average axial electric field have to be calculated simultaneously considering a given set of boundary conditions. In this paper the method is applied to the Koppelmann arc. In addition the paper reports upon some experiences in applying this method to the computation of further arc configurations.     

Electric power switches

A review is given of the physics and engineering behavior of arcs in vacuum and axial gas blast under the conditions found in high-voltage circuit breakers. The topics included are: the zero energy switch; current limiting switches; arc control; the gas-blast circuit breakers; the low-current gas-blast arc; arcing with ablation; interruption dynamics; arc modeling; vacuum as a switching element; the vacuum arc; the constricted arc; and the properties of SF₆     

月球微磁层的探测

近月空间环境中的等离子体特性是嫦娥一号及二号卫星的重要科学探测目标之一.基于嫦娥卫星上搭载的太阳风离子探测器(SWID)的测量结果,文章作者对月球表面磁异常结构(LMA)与太阳风相互作用这一空间科学中的热点问题进行了探索,并通过质子相空间分布的信息,初步确认了磁异常结构可以对入射原始太阳风起到屏蔽及加热的作用,形成所谓的"微磁层"结构.这是国际上为数不多的微磁层存在证据之一.文章作者期待这一研究(及后续工作)将不仅对月球表面空间风化效应的研究产生推动作用,同时也将有助于百公里尺度上(即质子回旋半径与宏观尺度相当条件下)的磁层物理学研究的发展.     

Critical layer singularities and complex eigenvalues in some differential equations of mathematical physics

Singular differential equations are a common feature of many problems in mathematical physics. It is often the case that systems with a similar mathematical structure can arise in many different contexts. In this article, mathematically related problems are drawn from areas as diverse as hydrodynamics (with applications to oceanography and meteorology), magnetohydrodynamics and plasma physics (with applications to astrophysics and geophysics, especially solar physics, ionospheric and magnetospheric physics; also nuclear fusion devices), acoustics, electromagnetics, quantum mechanics and nuclear physics. One major unifying feature common to the problems discussed here is the existence of complex eigenvalues, often associated with so-called “classical self-adjoint” equations. No real contradiction is involved here, but the resulting wave functions are often referred to variously as “radioactive states”, “damped resonances”, “leaky waves”, “non-modal solutions” , “singular modes”, “virtual modes”, or “improper eigenfunctions”. In the hydrodynamics of shear flows, such modes are associated with the existence of “critical layers” at which a singularity occurs in the governing (ordinary) differential equation. Similar, but usually more general singular layers are known to occur in equations arising in many of the above-mentioned contexts, and it is the purpose of this review to identify the nature of these singular layers and complex eigenvalues, and the relationships that exist between the different context in which they are found, and in particular to emphasize the occurrence of and interpretation of complex eigenvalues in quantum mechanics. Thus the “exponential catastrophe” is a clearly identified and recurring theme throughout this article by virtue of the similarities that exist between the classical and quantum system discussed here. The examples quoted from quantum mechanics are simple in form, and found in many standard texts, but the virtue of including them here is twofold: the results are easy to understand and relate to the more complicated “classical” systems, and they provide a valuable didactic and pedagogic tool for those readers whose background in quantum mechanics is limited. It is also hoped that this article will be of interest to readers who wish to become more acquainted with some aspects of hydrodynamics and magnetohydrodynamics.     

Qualitative analysis and asymptotics of solutions of generalized KdV-class equations

We study the asymptotics and the structure of solutions of generalized KdV-class equations with an arbitrary nonlinearity index, which are extensively used in the physics of ionospheric and magnetospheric plasma, hydrodynamics, and aerodynamics. KdV-class equations are generalized by introducing higher-order dispersion correction and terms describing dissipation and instability caused by numerous factors. Using asymptotic analysis and analysis of solutions in the phase space, we distinguish among different classes of solutions of soliton and nonsoliton types. North-East Complex Research Institute of the Far East Branch of Russian Academy of Sciences; Pedagogical University, Magadan, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 3, pp. 328–344, March, 1997.     

Measurements of the cross-sections for the photoproduction of positive pions on hydrogen in the region of the first resonance

In this paper the properties and the dependence upon parameters of those quantities are investigated, which are characteristic for the gas-heating process in electric arcs with axial gas flow. Starting with the equations of the one-fluid-model of plasma physics three various methods are derived, to calculate analytically or numerically the thermal and electrical entities of the inlet region of the arc. With these results expressions can be given for the thermal and electrical inlet length. Further the azimuthal component of the velocity and its inlet length are determined. A discussion of the results will be outlined in a later paper (part II).     

Der Einfluß einer radialen Masseneinströmung auf elektrische Lichtbögen

In this paper the influence of a radial instreaming gas on electric arcs is investigated. An axial or an azimuthal mass flow may be superimposed to the radial one. Using the basic equations of the single-fluid model of plasma physics the important properties and parameter dependences are numerically calculated and discussed. The results are compared with those of a corresponding arc without an instreaming radial mass flow. Using an arc heater with radial mass flow it is possible to reach much higher axis temperatures and enthalpy densities. Choosing a set of well selected working conditions nearly the whole electric input may be transformed into axial enthalpy flux of the gas to be heated. The paper illustrates the mutual interaction between the dynamic and thermic functions of an electric arc.     

First and second order non-equilibrium phase transition and evidence for non-extensive Tsallis statistics in Earth’s magnetosphere

In this paper strong evidence is provided for significant far from equilibrium phase transition processes in the Earth’s magnetosphere as revealed by the nonlinear analysis of in situ observations. These results constitute the solid base for the solution of the durable controversy about the chaotic or non-chaotic character of the magnetospheric dynamics. During the last two decades the concept of low dimensional chaos was supported by theoretical and experimental methods by our group in Thrace and others scientists, as an explicative paradigm of the magnetospheric dynamics including substorm processes. In parallel, the concept of self-organized criticality (SOC) and space-time intermittency was introduced as new and opposing to low dimensional chaos concepts for modeling the magnetospheric dynamics. Novel results concerning the nonlinear analysis of in situ space plasma data (magnetic-electric field, energetic particles and bulk plasma flow time series) obtained by the Geotail spacecraft presented in this paper for the first time reveal the following: (a) Coexistence of SOC and chaos states in the magnetospheric system and global phase transition from one state to the other during substorms. (b) Strong intermittent turbulent character of the magnetospheric system at the SOC or the low dimensional chaos states. (c) Clear indications for non-extensivity and q-Gaussian statistics during periods of low dimensional and chaotic dynamics of the magnetosphere. (d) Low dimensional and nonlinear space plasma dynamics in the day side magnetopause and bow shock dynamics. The dual character of the magnetospheric dynamics including low dimensional chaotic (coherent) and high dimensional turbulent states, as supported in this paper, is in agreement and verifies previous theoretical and experimental studies.     

Dynamics of the Magnetospheric Cyclotron ELF/VLF Maser in the Backward-Wave-Oscillator Regime. I. Basic Equations and Results in the Case of a Uniform Magnetic Field

We consider the nonlinear dynamics of absolute instability of whistler-mode waves in the Earth's magnetosphere in the presence of a step-like deformation in the distribution function of energetic electrons. Development of this instability, implying the transition of the magnetospheric cyclotron maser to the regime of a backward-wave oscillator (BWO), was proposed earlier as a generation mechanism of magnetospheric chorus emissions. We derive simplified nonlinear equations describing the dynamics of the magnetospheric BWO in the case of low efficiency of wave-particle interactions. Numerical simulations of these equations confirm qualitative similarity of the laboratory and magnetospheric BWOs and justify quantitative estimates of parameters of chorus emissions. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 9, pp. 719–729, September 2005.     

Magnetospheric dynamics during the storm of February 14, 2009

The structure of the magnetic field in the magnetospheric during the storm of February 14, 2009 is studied. The model parameters that characterize the magnetospheric magnetic field are calculated every hour on the basis of solar wind data and the evolution of the magnetic field during the storm is reproduced using the A2000 model of the Earth’s magnetosphere. It is shown that extremely quiet geomagnetic conditions in 2009 promoted the expansion of the magnetosphere and were favorable for the formation of magnetic-island-like structures (plasmoids) in the geomagnetic tail. It is ascertained that negative variations in the B_z component could occur in the nightside magnetosphere in situations where the magnetic flux through the tail lobes exceeded certain thresholds, which depend on the parameters of the magnetospheric current systems. It is shown that the formation of magnetic islands decreases the magnetic flux through the tail lobes and prevents excessively strong development of the magnetic field in the tail.     

Global magnetohydrodynamic simulations of the magnetosphere

The authors demonstrate the use of a global MHD (magnetohydrodynamic) simulations to study the magnetospheric configuration by reviewing some of the results obtained from the Ogino model. The authors start by considering the steady-state configuration of the magnetosphere in the absence of an IMF (interplanetary magnetic field), and then demonstrate how that configuration is changed when a northward or southward IMF is introduced. It is noted that the magnetosphere is very dynamic and since global MHD simulations are intrinsically time-dependent, they offer the possibility of modeling the time-sequence of events in the magnetosphere. Finally results of a calculation in which a magnetospheric substorm is modeled are presented     

A cellular dynamical mean field theory approach to Mottness

We investigate the properties of a strongly correlated electron system in the proximity of a Mott insulating phase within the Hubbard model, using a cluster generalization of the dynamical mean field theory. We find that Mottness is intimately connected with the existence in momentum space of a surface of zeros of the single particle Green’s function. The opening of a Mott-Hubbard gap at half filling and the opening of a pseudogap at finite doping are necessary elements for the existence of this surface. At the same time, the Fermi surface may change topology or even disappear. Within this framework, we provide a simple picture for the appearance of Fermi arcs. We identify the strong short-range correlations as the source of these phenomena and we identify the cumulant as the natural irreducible quantity capable of describing this short-range physics. We develop a new version of the cellular dynamical mean field theory based on cumulants that provides the tools for a unified treatment of general lattice Hamiltonians.     

Strong cosmic ray cutoff rigidity decreases during great magnetospheric disturbances

The theoretical and experimental cosmic ray cutoff rigidities during great magnetospheric disturbances in November 2004 and May 2005 have been determined. The theoretical geomagnetic cutoffs were calculated by the trajectory tracing method in the magnetic field of Tsyganenko’s magnetospheric model T03, which describes great magnetospheric disturbances (at Dst < 65 nT). The experimental geomagnetic cutoffs were determined by the spectrographic global survey method on the basis of the world network data. The cutoff rigidity decreases at Dst minima can reach 70–80% for theoretical cutoffs and ～40% for experimental cutoffs at mid latitudes.     

The atmospheric-pressure plasma jet: a review and comparison toother plasma sources

Atmospheric-pressure plasmas are used in a variety of materials processes. Traditional sources include transferred arcs, plasma torches, corona discharges, and dielectric barrier discharges. In arcs and torches, the electron and neutral temperatures exceed 3000°C and the densities of charge species range from 10¹⁶-10¹⁹ cm^-3. Due to the high gas temperature, these plasmas are used primarily in metallurgy. Corona and dielectric barrier discharges produce nonequilibrium plasmas with gas temperatures between 50-400°C and densities of charged species typical of weakly ionized gases. However, since these discharges are nonuniform, their use in materials processing is limited. Recently, an atmospheric-pressure plasma jet has been developed, which exhibits many characteristics of a conventional, low-pressure glow discharge. In the jet, the gas temperature ranges from 25-200°C, charged-particle densities are 10 ¹¹-10¹² cm^-3, and reactive species are present in high concentrations, i.e., 10-100 ppm. Since this source may be scaled to treat large areas, it could be used in applications which have been restricted to vacuum. In this paper, the physics and chemistry of the plasma jet and other atmospheric-pressure sources are reviewed