scholarly journals 3D study of centrifugal acceleration in isotropic photon fields

2019 ◽  
Vol 28 (11) ◽  
pp. 1950141
Author(s):  
G. G. Bakhtadze ◽  
V. I. Berezhiani ◽  
Z. Osmanov
Keyword(s):  
Magnetic Field ◽  
Single Particle ◽  
Stable Equilibrium ◽  
Charged Particles ◽  
Relativistic Dynamics ◽  
Centrifugal Acceleration ◽  
Study Behavior ◽  
Field Lines ◽  
Particle Approach

In this paper, we study relativistic dynamics of charged particles corotating with prescribed trajectories, having the shape of dipolar magnetic field lines. In particular, we consider the role of the drag force caused by the photon field the forming of equilibrium positions of the charged particles. Alongside a single particle approach, we also study behavior of ensemble of particles in the context of stable positions. As we have shown, the together they create surfaces where particles are at stable equilibrium positions. In this paper, we examine these shapes and study parameters they depend on. It has been found that under certain conditions, there are two distinct surfaces with stable equilibrium positions.

On the motion of charged particles in a sheared force-free magnetic field

2002 ◽  
Vol 67 (2-3) ◽  
pp. 215-221 ◽  
Author(s):  
G. E. VEKSTEIN ◽  
N. A. BOBROVA ◽  
S. V. BULANOV
Keyword(s):  
Magnetic Field ◽  
Spatial Scale ◽  
Single Particle ◽  
Charged Particles ◽  
Magnetic Confinement ◽  
Larmor Radius ◽  
Field Variation ◽  
Particle Trajectories ◽  
Field Lines ◽  
Actual Particle

This paper considers single-particle trajectories in a planar sheared force-free magnetic field. A specific feature of this magnetic configuration is the absence of both gradient and curvature magnetic drifts, as well as a diamagnetic force along field lines. Therefore, in the framework of the drift approximation, the motion of the particle guiding centre does not feel the magnetic field's non-uniformity. Here we discuss how the latter affects actual particle trajectories, making them quite different from simple circular gyromotion even when the Larmor radius is small. It is also shown how magnetic confinement ceases to work when the Larmor radius becomes comparable to the spatial scale of the field variation.

Synchrotron Radiation Spectra

1972 ◽  
Vol 2 (3) ◽  
pp. 142-144 ◽  
Author(s):  
L. J. Gleeson ◽  
K. C. Westfold
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Energy Distribution ◽  
Power Law ◽  
Uniform Magnetic Field ◽  
Charged Particles ◽  
Radiation Spectra ◽  
Field Lines

In this paper we give an account of the corrections that must be made to the formula for the emissivity ηf due to a power-law energy distribution of ultrarelativistic charged particles in a uniform magnetic field B0 in directions well away from the field lines when the effects of upper and lower cut-off values E2 and E1 in the energy distribution are not negligible.

Magnetic Field Aligned Potentials as an Acceleration Mechanism at Jupiter

2021 ◽  
Author(s):  
Dave Constable ◽  
Licia Ray ◽  
Sarah Badman ◽  
Chris Arridge ◽  
Chris Lorch ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Temporal Evolution ◽  
Charged Particles ◽  
Uniform Mesh ◽  
Time Varying ◽  
Potential Structure ◽  
Field Aligned Current ◽  
Field Lines ◽  
The Magnetic Field ◽  
Insight Into

<p>Since arriving at Jupiter, Juno has observed instances of field-aligned proton and electron beams, in both the upward and downward current regions. These field-aligned beams are identified by inverted-V structures in plasma data, which indicate the presence of potential structures aligned with the magnetic field. The direction, magnitude and location of these potential structures is important, as it affects the characteristics of any resultant field-aligned current. At high latitudes, Juno has observed potentials of 100’s of kV occurring in both directions. Charged particles that are accelerated into Jupiter’s atmosphere and precipitate can excite aurora; likewise, particles accelerated away from the planet can contribute to the population of the magnetosphere.</p> <p>Using a time-varying 1-D spatial, 2-D velocity space Vlasov code, we examine magnetic field lines which extend from Jupiter into the middle magnetosphere. By applying and varying a potential difference at the ionosphere, we can gain insight into the effect these have on the plasma population, the potential structure, and plasma densities along the field line. Utilising a non-uniform mesh, additional resolution is applied in regions where particle acceleration occurs, allowing the spatial and temporal evolution of the plasma to be examined. Here, we present new results from our model, constrained, and compared with recent Juno observations, and examining both the upward and downward current regions.</p>

Theory and observations of switchbacks’ evolution in the solar wind

2021 ◽  
Author(s):  
Anna Tenerani ◽  
Marco Velli ◽  
Lorenzo Matteini
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Radial Magnetic Field ◽  
Open Questions ◽  
Coronal Activity ◽  
Turbulent Heating ◽  
Field Lines ◽  
Radial Evolution ◽  
Field Correlation

<p>Alfvénic fluctuations represent the dominant contributions to turbulent fluctuations in the solar wind, especially, but not limited to, the fastest streams with velocity of the order of 600-700 km/s. Alfvénic fluctuations can contribute to solar wind heating and acceleration via wave pressure and turbulent heating. Observations show that such fluctuations are characterized by a nearly constant magnetic field amplitude, a condition which remains largely to be understood and that may be an indication of how fluctuations evolve and relax in the expanding solar wind. Interestingly, measurements from Parker Solar Probe have shown the ubiquitous and persistent presence of the so-called switchbacks. These are magnetic field lines which are strongly perturbed to the point that they produce local inversions of the radial magnetic field. The corresponding signature of switchbacks in the velocity field is that of local enhancements in the radial speed (or jets) that display the typical velocity-magnetic field correlation that characterizes Alfvén waves propagating away from the Sun. While there is not yet a general consensus on what is the origin of switchbacks and their connection to coronal activity, a first necessary step to answer these important questions is to understand how they evolve and how long they can persist in the solar wind. Here we investigate the evolution of switchbacks. We address how their evolution is affected by parametric instabilities and the possible role of expansion, by comparing models with the observed radial evolution of the fluctuations’ amplitude. We finally discuss what are the implications of our results for models of switchback generation and related open questions.</p>

scholarly journals Centrifugal acceleration of protons by a supermassive black hole

2020 ◽  
Vol 492 (4) ◽  
pp. 4884-4891 ◽  
Author(s):  
Ya N Istomin ◽  
A A Gunya
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Galactic Nuclei ◽  
Rotation Frequency ◽  
Azimuthal Velocity ◽  
Lorentz Factor ◽  
Centrifugal Acceleration ◽  
Poloidal Magnetic Field ◽  
Field Lines ◽  
Sgr A

ABSTRACT Centrifugal acceleration is due to the rotating poloidal magnetic field in the magnetosphere that creates the electric field which is orthogonal to the magnetic field. Charged particles with finite cyclotron radii can move along the electric field and receive energy. Centrifugal acceleration pushes particles to the periphery, where their azimuthal velocity reaches the speed of light. We calculated particle trajectories by numerical and analytical methods. The maximum obtained energies depend on the parameter of the particle magnetization κ, which is the ratio of rotation frequency of magnetic field lines in the magnetosphere ΩF to non-relativistic cyclotron frequency of particles ωc, κ = ΩF/ωc <<1, and on the parameter α which is the ratio of toroidal magnetic field BT to the poloidal one BP, α = BT/BP. It is shown that for small toroidal fields, α < κ1/4, the maximum Lorentz factor γm is only the square root of magnetization, γm = κ−1/2, while for large toroidal fields, α > κ1/4, the energy increases significantly, γm = κ−2/3. However, the maximum possible acceleration, γm = κ−1, is not achieved in the magnetosphere. For a number of active galactic nuclei, such as M87, maximum values of Lorentz factor for accelerated protons are found. Also, for special case of Sgr. A*, estimations of the maximum proton energy and its energy flux are obtained. They are in agreement with experimental data obtained by HESS Cherenkov telescope.

scholarly journals New Radiation Formulae of Relativistic Electrons in Curved Magnetic Field Lines

2002 ◽  
Vol 199 ◽  
pp. 400-401
Author(s):  
Ya.M. Sobolev
Keyword(s):  
Magnetic Field ◽  
Charged Particles ◽  
Relativistic Electrons ◽  
Force Line ◽  
Radiation Mechanism ◽  
Field Lines

Radiation mechanism for relativistc charged particles spiraling along curved magnetic field is considered. Emission from many electron revolutions around force line is taken into account.

V. Heating and Dynamics of Chromosphere and Corona

1988 ◽  
Vol 20 (1) ◽  
pp. 100-102
Author(s):  
G.E. Brueckner
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Acoustic Waves ◽  
Convection Zone ◽  
Flux Tubes ◽  
Magnetic Structures ◽  
Convective Motions ◽  
Field Lines ◽  
The Magnetic Field

The crucial role of magnetic fields in any mechanism to heat the outer solar atmosphere has been generally accepted by all authors. However, there is still no agreement about the detailed function of the magnetic field. Heating mechanisms can be divided up into 4 classes: (I) The magnetic field plays a passive role as a suitable medium for the propagation of Alfvén waves from the convection zone into the corona (Ionson, 1984). (II) In closed magnetic structures the slow random shuffling of field lines by convective motions below the surface induces electric currents in the corona which heat it by Joule dissipation (Heyvaerts and Priest, 1984). (Ill) Emerging flux which is generated in the convection zone reacts with ionized material while magnetic field lines move through the chromosphere, transition zone and corona. Rapid field line annihilation, reconnection and drift currents result in heating and material ejection (Brueckner, 1987; Brueckner et al., 1987; Cook et al., 1987). (IV) Acoustic waves which could heat the corona can be guided by magnetic fields. Temperature distribution, wave motions and shock formation are highly dependent on the geometry of the flux tubes (Ulmschneider and Muchmore, 1986; Ulmschneider, Muchmore and Kalkofen, 1987).

scholarly journals L-shell and energy dependence of magnetic mirror point of charged particles trapped in Earth’s magnetosphere

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Pankaj K. Soni ◽  
Bharati Kakad ◽  
Amar Kakad
Keyword(s):  
Magnetic Field ◽  
Charged Particles ◽  
Magnetic Mirror ◽  
Theoretical Expression ◽  
Neutral Atmosphere ◽  
Loss Cone ◽  
Field Lines ◽  
Mirror Point ◽  
The Magnetic Field ◽  
Shell Energy

Abstract In the Earth’s inner magnetosphere, there exist regions like plasmasphere, ring current, and radiation belts, where the population of charged particles trapped along the magnetic field lines is more. These particles keep performing gyration, bounce and drift motions until they enter the loss cone and get precipitated to the neutral atmosphere. Theoretically, the mirror point latitude of a particle performing bounce motion is decided only by its equatorial pitch angle. This theoretical manifestation is based on the conservation of the first adiabatic invariant, which assumes that the magnetic field varies slowly relative to the gyro-period and gyro-radius. However, the effects of gyro-motion cannot be neglected when gyro-period and gyro-radius are large. In such a scenario, the theoretically estimated mirror point latitudes of electrons are likely to be in agreement with the actual trajectories due to their small gyro-radius. Nevertheless, for protons and other heavier charged particles like oxygen, the gyro-radius is relatively large, and the actual latitude of the mirror point may not be the same as estimated from the theory. In this context, we have carried out test particle simulations and found that the L-shell, energy, and gyro-phase of the particles do affect their mirror points. Our simulations demonstrate that the existing theoretical expression sometimes overestimates or underestimates the magnetic mirror point latitude depending on the value of L-shell, energy and gyro-phase due to underlying guiding centre approximation. For heavier particles like proton and oxygen, the location of the mirror point obtained from the simulation deviates considerably (∼ 10°–16°) from their theoretical values when energy and L-shell of the particle are higher. Furthermore, the simulations show that the particles with lower equatorial pitch angles have their mirror points inside the high or mid-latitude ionosphere.

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