Black Sea School on Plasma Physics (Kiten, July 1–9, 2006)
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Erdélyi Yuriy Taroyan Mark Wardle A. Raouak Dmitry Bisikalo Yavor Shopov Alexander Dolgov Inna Dolgova Yasuko Honda Aglika Sawtchenko Rossitsa Miteva Gottfried Mann Roumyana Mitzeva Ilia Roussev Yana Georgi Manev Todor Mishonov Michael Ruderman Larissa Ruderman Gunnar Hornig Sergej Moiseenko Thierry Dudok de Wit Madalina Vlad Florin Vyacheslav Zhuravlev Nikolai Shakura Alexander Oreshko Krassimira Iankova Pavel Kaygorodov M. Vellante Diana Stoykova Lyuba Boundova Miglena Milcheva Dessislava Torbova Milena Mineva Borislav Petkov Nikolay Tankovski Petko Nenovski Ivan Zhelyazkov |
Department of Applied Mathematics, Recent high-resolution solar and space missions have opened new avenues for 21st century plasma physics. With unprecedented details a very rich structure of the solar atmosphere is unveiled. In my review talk I will introduce the students to solar terminus techniques. I will define and describe the abundant and fascinating structure of the Solar Zoo, starting from peering inside the Sun, through the solar atmosphere, solar storms (flares, solar quakes, solar wind) into space weather. The concept of magneto- hydrodynamics will be introduced and applied to describe inhabitants of the Solar Zoo. Magnetohydrodynamic
Waves and Oscillations in Solar Plasmas The solar atmospheric plasma is embedded in ubiquitous magnetic field. This magnetic structuring acts as excellent wave guides. Plasma waves and oscillations are able to propagate from subsurface solar regions through the solar atmosphere into the interplanetary space. Observations and theoretical modelling of waves can give as excellent diagnostic tools about the state of solar plasma. Current observational advances in solar wave theory will be discussed. Linear wave theory will be introduced. The current literature and latest progress on wave excitation, propagation and their dissipation will be reviewed. The concept of solar magneto-seismology, a novel method of studying the atmosphere of the Sun and late-type stars will also be discussed. Outlook to future missions in relation of the observations of these magnetic waves will close my lecture. The self-consistent model of X-ray generation in binary Be/X stars is proposed. Using the model of expanding envelope of optical B star, we determine, that value of mass transfer rate via the inner Lagrangian point is large enough to generate the observed X-ray luminosity of Be/X stars. It was shown, using numerical computations, that the orbital period correlates with X-ray luminosity of Be/X star. The comparison shows good agreement of achieved results with observations. The review of gas dynamic models used for the description of the accretion discs in close binaries is presented. Main features of the flow structure are summarized. The special attention is paid at physics of accretion discs in binary systems and particularly at spiral waves in discs. Institut de Formation Technique, 105 rue Sergent, Med Missaoui, Ain bordja, Casa Maroc Particles Acceleration and Non Gaussian Effect in the Relativistic Electrostatic Wave Packet CNRS-Université d’Orléans, Space plasmas are a hallmark for nonlinear and
collective phenomena. Yet, most studies of experimental or simulated
data involve techniques that are based on the premises that the
underlying phenomena are linear, stationary, bounded, etc.
Non-linearity and non-stationarity,
rather than being a nuisance, can provide deep insight into the
underlying physics. I will focus on two topics. The first one is
non-linearity in the presence of wave phenomena. Models involving the
weak interaction of waves arise in various contexts such as weak
turbulence theory. Higher order generalisations
of the well-known Fourier power spectrum (called higher order spectra)
are the appropriate quantities for probing such nonlinear interactions.
They can for example be used to identify energy cascades between
different interacting waves. The second topic is multiscale analysis of plasmas. In turbulence, what matters is not just the distribution of the scales, but also the interplay between different scales. Multiscddwit@cnrs-orleans.frale analysis (i.e. wavelet analysis) is ideally suited for this. Time-frequency descriptions have indeed become increasingly popular for investigating properties such as intermittency, discontinuities etc. Some examples will be given, based on experimental and simulated plasma data. Moscow Aviation Institute, Existence of current-carrying channels between
a core and a ring external layer of a star testifies that radiation
star is the electric domain of spherical geometry. The core of a star
possesses the superfluous negative charge. The ring external layer
(photosphere) possesses the superfluous
positive charge. The radial and ambipolar
electric fields exist between the core and ring layer. The system of
charges rotating in space creates a magnetic poloidal
field so-called a magnetic dynamo. A contortion of induction lines in
regions of star equator and its poles is possible to explain by mean of
difference in rotation speed of plasma in specified ones. The ring
external layer of a star is magnetized. The system of type the domain
of a spherical configuration is a plasma crystal. Significant life time
of such systems is caused by that in the domains are markedly reduced
processes of recombination because of surplus of charges of one mark
and lack of charges of an opposite mark into core or a ring external
layer. The similar situation is realized in balls lighting, which are
structural micro-analogues of stars. The analysis of the data gives the basis to
consider, that in stars the accelerating methoddwit@cnrs-orleans.frd of synthesis is realized. In current-carrying
channels the flat domains are periodically formed, which create the
intensive microwave radiation. Ions captured by the cross
electromagnetic waves collect energy, which is sufficient for
overcoming Coulomb potential barrier. Junction of current-carrying
channels on the Sun (October 2006) has taken place as a result of
charge change. Availability of Universe frontier reflecting probing radiation in Hubbl’s experiment and presence in the centre of the Universe in region of the Milky Way of a huge “black hole”, which are connected “an axis of evil”, are analogues of current-carrying channel. It testifies that the Universe is the huge domain. The Universe together with galaxies and star congestions represents oscillatory system. As a result of an exchange of energy between elements of the system at the definite positions of consistent components is observed an amplification of activity. Gottfried MannAstrophysikalisches Institut
During solar flares a
large amount of energetic electrons are produced.
These electrons are responsible for both the
non-thermal radio and X-ray radiation. NASA's space mission RHESSI is
able to provide hard X-ray images with a highly temporal and spatial
resolution since its launch in February 2002. A
brief introduction in the RHESSI mission and the contribution of Dipartimento di Fisica,
Università
dell’Aquila,
In this lecture we review the main characteristics of the magnetospheric field line resonance (FLR) phenomenon both from a theoretical and an observative point of view. Magnetospheric diagnostic capabilities of FLRs are also highlighted. We first review the basic magnetohydrodynamic (MHD) wave modes in a uniform cold plasma. We then examine the MHD wave modes in a dipole field, paying particular attention to the axisymmetric toroidal mode. Basic theoretical characteristics of magnetospheric FLRs are derived using the simple Southwood’s box model. We then discuss about the possible drivers of FLRs, and about the effects of the ionosphere in ground observations. A review of current techniques for detecting FLRs in space and on the ground is also presented. Finally we illustrate how FLRs can be used to remote sense the magnetospheric plasma mass density and to monitor the magnetospheric dynamics. Space Research Institute, The results of 2D numerical simulations of magnetorotational supernova explosion are presented. The shape of the explosion qualitatively depends on the initial configuration of the magnetic field. In the case of the quadrupole-like initial magnetic field the supernova explosion develops mainly along equatorial plane. The initial dipole like magnetic field leads to the mildly collimated axial jet. Magnetorotational instability (MRI) was found during simulations of the magnetorotational supernova explosion. MRI leads to the exponential growth both poloidal and toroidal magnetic fields. This work studies the
plasma interactions in the far solar corona. We obtained several
experimental evidences that the far coronal streamers (observed
directly only from the space) do not emit or reflect white light, but
emit only in broad spectral lines. In this talk we consider possible
interactions of the solar plasma, which could produce such emission to
explain obtained spectra from the far coronal streamers at 8 solar
radii far from the Sun. Here we develop a new
technique for registration of the far solar corona from ground
observations. It allows research and estimation of finest differences
of the colour and the
structure of the elements of the images. It makes possible also
visualization of fine invisible with naked eye details (due to the
visually undetectably low differences of their brightness from the
neighbor parts of the image) of the studied objects. We used this new
technique to study otherwise invisible details of the solar corona and
to register the far solar corona far beyond previous ground
observations. Obtained images of eclipsed solar corona are compared
with the images from the Large Angle Space Coronagraph (LASCO)- C3 and C2 coronagraphs
registered simultaneously from the space. Ground images filtered by the
new technique reveal the main structures of the far solar corona
recorded from the space up to 20 solar radii far from the Sun during
the total solar eclipse on This new technique is very useful for registration of the far solar corona from ground observations producing images comparable to those from space observations. Institute for Astronomy, Ejections of
magnetized plasma from the Sun, commonly known as Coronal Mass
Ejections (CMEs), are
one of the most stunning manifestations of solar activity.
Those solar eruptions, among other effects, also
drive shock waves as they evolve in interplanetary space, which act as
powerful accelerators of charged particles in the solar wind.
Thus produced Solar Energetic Particles (SEPs) are transported along the
interplanetary magnetic field lines, and they can create major
radiation hazards for spacecraft and astronauts in outer space.
The physical causes of CMEs
have been debated by the solar physics community for over three decades
now. The production of SEPs also lacks detailed
understanding of the important physical mechanisms involved.
To date, there is no CME or SEP model that is
sufficiently well developed to explain the real events, although some
models have succeeded in describing their general properties.
There is a consensus in the community, however, that
CMEs and SEPs are inter-related, and that
they play a major role in governing the state and dynamics of the
coupled Sun–Earth system in which we live.
Department of Electrical and Information
Technology, Cosmic ray particles are more rapidly accelerated in the oblique shocks than in the parallel shocks, as a result of mirror reflection at the shock surface and slower diffusion in the shock normal direction. We investigate how quantitatively these effects contribute to reducing the acceleration time over the whole range of magnetic field inclinations. The results are important for a detailed understanding of the mechanism of particle acceleration by an oblique shock in space and heliospheric plasmas. Association The problem of structures generated from
turbulent states in fluids and plasmas has become a major subject of
investigation, with many potential applications. We
will focus here on the theoretical approach based on formulation of the
physical model as a classical field theory. The
physical problem consists of dynamical generation of structure from a
fluctuating field and progressive suppression of the random spectral
component. Large scale flows in
quasi-ideal fluids, transport in magnetically confined plasma,
stationary atmospheric vortices like the tropical cyclone, are included
in this category and will be discussed. We will briefly introduce theoretical
pre-requisite instruments: Chern–Simons
action, non-Abelian
Yang–Mills field theory and algebraic structures. We will develop a detailed description of the
application to physical models of practical importance.
For two-dimensional ideal fluids the Euler equation
is mapped on a model of point-like vortices interacting via a
logarithmic potential. We show that
the action of the field-theoretical model has an extremum at self-dual states and
we provide a purely analytical derivation of the sinh-Poisson equation. For two-dimensional magnetically confined
plasma we derive the equation governing the asymptotic states and
present a class of solutions relevant for enhanced confinement of tokamak fusion plasma. For the atmospheric vortex (tropical cyclone,
hurricane) we will present solutions having the same pattern of flow as
in observations and scaling laws of parameters of the structure of the
flow. Finally we discuss different possible developments. Department of Applied Mathematics, We consider one-dimensional motions of plasmas described by the set of ideal magnetohydrodynamic equations. We show that a circularly polarized one-dimensional Alfvén wave propagating along a constant magnetic field is an exact solution of this set of equations. The dispersion equation governing the stability of a circularly polarized Alfvén wave is derived. This equation is used to study the wave stability with respect to normal modes. The concept of absolute and convective instability is introduced. The recent results on the absolute and convective instability of circularly polarized Alfvén waves is presented and briefly discussed. Association The problem of charged particle transport in
stochastic magnetic fields is analyzed using a new statistical
approach, the decorrelation
trajectory method [1,2].
The Lagrangian
non-linearity determined by the space-dependence of the stochastic
magnetic field produces a process of magnetic line trapping, which
appears at large Kubo numbers. This trapping process leads to localized
segments of the magnetic lines with helicoidal
shapes, which form localized stochastic structures similar to magnetic
islands. They consist of magnetic
line winding around some local axis. Particles with arbitrary values of
the Larmor radius are
considered. We show that the
stochastic magnetic structures strongly influence particle transport.
The effect is different for small and large values
of the ratio of Larmor
radius over the correlation length of the stochastic magnetic field.
M. Vlad, F.
Spineanu, J.H. Misguich, R. Balescu, Phys. Rev. E 58 (1998)
7359. M. Vlad, F. Spineanu, Phys. Rev. E 70 (2004) 056304(14).Pres/Vlad.pdf Faculty of Physics, An overview of the
existing literature in the field of atmospheric electricity and
transient luminous events will be presented. Some
methods of detection of sprites and other electrical phenomena will be
revealed. The different types of
thunderstorms related to sprites will be discussed and a special
attention will be given to the peculiarities observed in the
characteristics of the thunderstorm systems over the Stenberg Astronomical Institute, Hydrodynamical stability of axisymmetric flows is of classical interest while studying the onset of turbulence in the accreting matter. The instability of laminar flow to infinitesimal disturbances points to possible turbulization of motion. It's generally accepted that astrophysical disks have almost keplerian angular velocity profile being stable according to Rayleigh criterion that is equivalent to the stability of axisymmetric disturbances. As a consequence, the non-axisymmetric types of disturbances were investigated by several authors in the middle 1980's. It turned out that free boundaries induce exponential growth of such modes in basic shear flow with negative gradient of specific angular momentum which implies the stability by Rayleigh criterion. In present work the non-axisymmetric sort of instability is reexamined in wide range of parameters for incompressible and compressible perfect fluid. Additionally, along with usual power law for angular velocity profile the Keplerian law with sinusoidal deviation was involved into the research. In the last case enthalpy gradient vanishes at the boundaries and this substantially modifies the dispersion relations for unstable modes. Dipartimento di
Fisica, Instituto Nazionale di Fisica
Nucleare, I-44100 Some mechanisms of generation of turbulent currents in the early Universe are discussed: (1) induction of primordial turbulence by large isocurvature fluctuations at neutrino decoupling through oscillations between active and sterile neutrinos; (2)by non-linear generation of vorticity at recombination epoch (in the second order in perturbations). The results are applied to generation of large scale cosmic magnetic fields. N. ShakuraStenberg Astronomical Institute, The term
“accretion” has Latin origin (accretio) and means increasing,
adding something. In astronomy, the accretion term is used to describe
the fall of rarefied medium onto central gravitating object of
different nature. Disk accretion assumes
the fall of matter with significant angular momentum.
Disk accretion results in the formation of an oblate
structure called accretion disk. To
the first approximation, the matter in accretion disks rotates in
circular orbits. The rotational law
is close to the Keplerian
one. If there is an efficient viscosity
mechanism (turbulence and/or magnetic field) in a differentially
rotating disk, the angular momentum starts exchanging between adjascent layers. The
angular momentum is transferred from layers locating closer to the
gravitating center to those locating further away, allowing for radial
motion of gas toward the center to set in. This
motion in general case is accompanied by gravitational energy release.
A fraction of this energy transforms into heat which
is radiated away from the accretion disk surface. The disk accretion
naturally appears in close binary stellar systems as a result of mass
transfer from one component to more compact one with size much smaller
than that of the binary. So the
compact stellar remnants (white dwarfs, neutron stars, black holes) are
the most appropriate gravitating centers for disk accretion. Inner
parts of accretion disks around neutron stars and black holes are
heated up to very high temperatures and emit in the X-ray energy range.
The theory of disk accretion (the structure of accretion disks and their observational appearances) was constructed in the beginning of 70s in papers by N.I. Shakura and R.A. Sunyaev. Almost simultaneously with these works, powerful X-ray sources in binary systems were discovered by UHURU satellite (R. Giacconi’s group). These sources proved to be accreting black holes and neutron stars in binaries with normal components. Matter is lost from their surfaces and accrete onto compact objects. A lot of accretion disks have been discovered over last decades around celestial bodies of different nature – from protoplanetary bodies to supermassive black holes in active galactic nuclei and quasars. The theory of disk accretion contains one fundamental dimensionless parameter (the so-called “alpha”'-parameter), which characterizes efficiency of the angular momentum exchange between the neighboring layers and can vary from zero to one. Analysis of available observations allows us to prescribe the value of this parameter. Non-stationary accretion disks around black holes in X-ray novae, in which characteristic evolutionary time-scales are determined by this parameter, seems to be the most relevant to such a study. Recent results, obtained by V.F. Suleimanov, G.V. Lipunova, and N.I. Shakura, showed that the value of the disk accretion alpha-parameter should be close to unity. Division of Mathematics, Magnetic reconnection
is an important process of structure formation in astrophysical plasmas.
Starting from basic concepts such as the
conservation laws for magnetic flux and field lines, magnetic
reconnection is introduced as a process capable of changing the global
topology of the magnetic field. The
basic characteristics of the process will be explained.
This includes among others the definition of a
magnetic reconnection rate, the question for slow and fast
reconnection, the implications of reconnection for magnetic helicity as well as the release
of magnetic energy. Two-dimensional
reconnection models will be first used to gain a basic understanding of
the process. Then the various
geometries in which three-dimensional reconnection can occur will be
reviewed. This covers the most
recent magnetic reconnection models for regions of non-vanishing
magnetic field as well as reconnection at magnetic null points.
A list of open problems will close this set of
lectures
Faculty of Physics, Heating of magnetized turbulent plasma is calculated in the framework of Burgers turbulence [A.M. Polyakov, Phys. Rev. E. 52 (1994) 6183]. There is calculated the energy flux of Alfvén waves along the magnetic field. The Alfvén waves are considered as intermediary between the turbulent energy and the heat. The derived results are related to wave channel of the heating of solar corona. After incorporating dissipation of convective plasma waves instabilities [G.D. Chagelishvili, R.G. Chanishvili, T.S. Hristov, and J.G. Lominadze, Phys. Rev. E 47 (1993) 366], and [A.D. Rogava, S.M. Mahajan, G. Bodo, and S. Marsaglia, A&A 399 (2003) 421] the suggested model of heating can be applied to analysis of missing viscosity of accretion discs and to reveal why the quasars are the most powerful sources of light in the universe. The theory supposes self-sustained turbulence and magnetic field in the shear flow. We suppose that applied Langevin–Burgers approach to turbulence can be helpful for other systems where we have intensive interaction between a stochastic turbulent system and waves [T. Hristov, C. Friehe, and S. Miller, Phys. Rev. Lett. 81 (1998) 5245] and [Nature 422 (2003) 55] and can be used in many multidisciplinary researches in hydrodynamics and magnetohydrodynamics. Department of Applied Mathematics, The talk is an introduction into basic magnetohydrodynamic (MHD) wave phenomena in space plasmas. The following issues will be addressed: the main types of MHD waves which exist in the solar–terrestrial environment; the excitation and damping mechanisms of MHD waves in solar atmospheric and magnetospheric structures; the role of instabilities, wave–flow and resonant interactions and their implications; the role of nonlinearity and dissipation. presentation
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Space Research Institute, Bulgarian Academy of Sciences, BG-1000 Sofia, Bulgaria, email: f7@space.bas.bg
We investigate the problem for generation of corona in a hot magnetized advective accretion disk. We discuss the appearance and the behavior of the magneto rotational instability (MRI). In this paper, we consider the connection of MRI with the generation of a corona in the disk. presentation >> proceeding >> |