scholarly journals Electron Outflow in Axisymmetric Pulsar Magnetospheres. II

1987 ◽  
Vol 40 (5) ◽  
pp. 687
Author(s):  
RR Burman
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Lorentz Factor ◽  
Surface Flow ◽  
Stellar Surface ◽  
Extended Version ◽  
Pulsar Magnetosphere ◽  
Poloidal Magnetic Field ◽  
Field Lines ◽  
Limiting Surface

Tn the axisymmetric pulsar magnetosphere model of Mestel et al. (1985), electrons, following injection with non-negligible speeds from the stellar surface, flow with moderate acceleration, and with poloidal motion that is closely tied to poloidal magnetic field lines, before reaching a limiting surface, near which rapid acceleration occurs. The present paper continues an analysis of flows which either encounter the limiting surface beyond the light cylinder (between the cones of zero axial magnetic field), or do not meet it at all. The formalism introduced by Mestel et aL for the description of the outflow is applied in an extended version which fully incorporates Yo, the emission Lorentz factor of the particles. This treatment removes the singularity of Yo at the stellar poles that occurred in the earlier work: because of a nonuniformity in taking the limit of nonrelativistic injection, full incorporation of Yo acts to keep it finite.

scholarly journals Electron Outflow in Axisymmetric Pulsar Magnetospheres

1985 ◽  
Vol 38 (5) ◽  
pp. 749 ◽  
Author(s):  
RR Burman
Keyword(s):  
Magnetic Field ◽  
Pulsar Magnetosphere ◽  
Poloidal Magnetic Field ◽  
Light Cylinder ◽  
Field Lines ◽  
Limiting Surface

Mestel et al. (1985) have recently introduced an axisymmetric pulsar magnetosphere model in which electrons leave the star with speeds that are non-negligible, but not highly relativistic, and flow with moderate acceleration, and with poloidal motion that is closely tied to the poloidal magnetic field lines, before reaching a limiting surface, near which rapid acceleration occurs. This paper presents an analysis of flows which either encounter the limiting surface beyond the light cylinder or do not meet it at all.

scholarly journals Distorted Dipole Magnetic Fields

1996 ◽  
Vol 160 ◽  
pp. 433-434
Author(s):  
Ron Burman
Keyword(s):  
Magnetic Field ◽  
Numerical Technique ◽  
Dipole Approximation ◽  
Pulsar Magnetosphere ◽  
Poloidal Magnetic Field ◽  
Numerical Work ◽  
Plasma Drift ◽  
Field Lines ◽  
Limiting Surface ◽  
The Magnetic Field

Mestel et al. (1985; MRΩ2) introduced an axisymmetric pulsar magnetosphere model in which electrons leave the star with non-negligible speeds and flow with moderate acceleration, and with poloidal motion that is closely tied to poloidal magnetic field lines, before reachingSL, a limiting surface near which rapid acceleration occurs. As well as these Class I flows, there exist Class II flows which do not encounter a region of rapid acceleration (Burman 1984, 1985b). The formalism introduced by MRΩ2to describe the moderately accelerated flows can be interpreted in terms of a plasma drift across the magnetic field, following injection along it (Burman 1985a).The MRΩ2formalism fully incorporates the toroidal magnetic field generated by the poloidal flow. The general formalism leaves the poloidal magnetic field unspecified, but, in the detailed development of MRΩ2, and in my papers, that field was taken to be the dipolar field of the star.Numerical work by Fitzpatrick & Mestel (1988a,b) suggested that the dipole approximation is inadequate. They developed a numerical technique for incorporating the modification to the poloidal magnetic field that is generated by the toroidal motions throughout the magnetosphere. They based their treatment on the hypothesis that those motions are such as to cancel the dipole field of the star, leaving a sextupole poloidal magnetic field at large distances.

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.

Electron Outflow in Pulsar Magnetospheres

1984 ◽  
Vol 5 (4) ◽  
pp. 467-469 ◽  
Author(s):  
R. R. Burman
Keyword(s):  
Magnetic Field ◽  
Pulsar Magnetosphere ◽  
Field Lines ◽  
Limiting Surface

Mestel, Wang and Westfold (1984; ‘MWW’) have recently introduced a pulsar magnetosphere model in which electrons leave the star with non-negligible, but not highly-relativistic, speeds, and flow with moderate acceleration along magnetic field lines before reaching a limiting surface, near which rapid acceleration occurs. Such moderately accelerated flows are analysed here. A second class of flows, which do not encounter a region of rapid acceleration, is found.

scholarly journals The effect of uniform magnetic field on spatial-temporal evolution of thermocapillary convection with the silicon oil based ferrofluid

2020 ◽  
Vol 24 (6 Part B) ◽  
pp. 4159-4171
Author(s):  
Shuo Yang ◽  
Rui Ma ◽  
Qiaosheng Deng ◽  
Guofeng Wang ◽  
Yu Gao ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Free Surface ◽  
Transverse Magnetic Field ◽  
Liquid Bridge ◽  
Thermocapillary Convection ◽  
Surface Deformation ◽  
Axial Magnetic Field ◽  
Transverse Magnetic ◽  
Surface Flow ◽  
Silicon Oil

A uniform axial or transverse magnetic field is applied on the silicon oil based ferrofluid of high Prandtl number fluid (Pr ? 111.67), and the effect of magnetic field on the thermocapillary convection is investigated. It is shown that the location of vortex core of thermocapillary convection is mainly near the free surface of liquid bridge due to the inhibition of the axial magnetic field. A velocity stagnation region is formed inside the liquid bridge under the axial magnetic field (B = 0.3-0.5 T). The disturbance of bulk reflux and surface flow is suppressed by the increasing axial magnetic field. There is a dynamic response of free surface deformation to the axial magnetic field, and then the contact angle variation of the free surface at the hot corner is as following, ?hot, B = 0.5 T = 83.34? > ?hot, B = 0.3 T = 72.16? > > ?hot,B = 0.1 T = 54.21? > ?hot, B = 0 T = 43.33?. The results show that temperature distribution near the free surface is less and less affected by thermocapillary convection with the increasing magnetic field, and it presents a characteristic of heat-conduction. In addition, the transverse magnetic field does not realize the fundamental inhibition for thermocapillary convection, but it transfers the influence of thermocapillary convection to the free surface.

scholarly journals Pulsar Electrodynamics — Pulsars and Puzzlers —

1996 ◽  
Vol 160 ◽  
pp. 409-416
Author(s):  
Shinpei Shibata
Keyword(s):  
Magnetic Field ◽  
Pair Creation ◽  
Gap Model ◽  
Pulsar Magnetosphere ◽  
Wind Model ◽  
Gedanken Experiment ◽  
Basic Understanding ◽  
Free Parameters ◽  
Pulsar Wind ◽  
Field Lines

AbstractA gedanken experiment presented here provides basic understanding of how the pulsar magnetosphere operates. We discuss current issues about the electric-field acceleration along magnetic field lines and subsequent pair creation, and also about the pulsar wind problem. It is stressed that any local model, such as the inner gap model, the outer gap model and the pulsar wind model, must have free parameters to link it to other part of the magnetosphere.

Zur Begrenzung der radial en Ausdehnung des Li chtbogenstromes durch ein axiales Magnetfeld. II. Skalengesetze und Vergleich mit Experimenten / On Limitation of the Radial Extent of the Arc Current by Means of an Axial Magnetic Field. II. Scaling Laws and Comparison with Experimental Results

1972 ◽  
Vol 27 (4) ◽  
pp. 652-670
Author(s):  
O. Klüber
Keyword(s):  
Magnetic Field ◽  
Cross Sections ◽  
Scaling Laws ◽  
Axial Magnetic Field ◽  
Angular Frequency ◽  
Model Calculations ◽  
Simple Geometry ◽  
Radial Extent ◽  
Arc Current ◽  
Field Lines

Abstract In an arc with superimposed axial magnetic field, radial current components cause a rotational motion of the plasma column and produce azimuthal Hall currents and hence electromotive forces such that the arc current is guided by the magnetic field lines. In the first part of this paper the steady-state plasma equations have been solved for a homogeneous plasma in simple geometry, allowance being made for finite viscosity. Here, scaling laws giving the radial extent of the arc current are obtained. In addition, electrodes with finite cross sections are treated. The results of model calculations agree well with experimental data. Generally, the model is applicable, if the angular frequency of the plasma is small compared with the ion gyration frequency.

scholarly journals Large-Scale Internal Magnetic Field of the Sun

1990 ◽  
Vol 138 ◽  
pp. 391-394
Author(s):  
A.E. Dudorov ◽  
V.N. Krivodubskij ◽  
A.A. Ruzmaikin ◽  
T.V. Ruzmaikina
Keyword(s):  
Magnetic Field ◽  
Differential Rotation ◽  
Large Scale ◽  
The Sun ◽  
Poloidal Magnetic Field ◽  
The Core ◽  
Torsional Waves ◽  
Formation And Evolution ◽  
Field Lines ◽  
The Magnetic Field

The behaviour of the magnetic field during the formation and evolution of the Sun is investigated. It is shown that an internal poloidal magnetic field of the order of 104 − 105 G near the core of the Sun may be compatible with differential rotation and with torsional waves, travelling along the magnetic field lines (Dudorov et al., 1989).

Coherent Curvature Emission in Pulsar Magnetospheres: Non-dipolar Geometric Effects

1993 ◽  
Vol 10 (3) ◽  
pp. 258-262 ◽  
Author(s):  
Qinghuan Luo
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Rotation Period ◽  
Lorentz Factor ◽  
Maser Emission ◽  
Specific Geometry ◽  
Field Lines ◽  
First Time ◽  
The Magnetic Field ◽  
Geometric Effects

AbstractThe effects of the specific geometry of the magnetic field (such as field lines with torsion) on curvature emission and absorption in pulsar magnetospheres are discussed. Curvature maser emission can arise from two effects: the curvature drift, as has already been discussed in the literature, and field line torsion as discussed here in detail for the first time. Maser emission due to field line torsion can operate only when the Lorentz factor is larger than a certain value. However, when the Lorentz factor of electrons or positrons is sufficiently high, curvature masering is due to both curvature drift and magnetic field line torsion. The optical depth in the case of field line torsion is estimated. It is shown that if torsion is due to rotation, the resultant luminosity should be dependent on the rotation period in such a way that shorter periods correspond to larger luminosities.

scholarly journals Zur Begrenzung der radialen Ausdehnung des Lichtbogenstromes durch ein axiales Magnetfeld

1970 ◽  
Vol 25 (11) ◽  
pp. 1583-1600
Author(s):  
O. Klüber
Keyword(s):  
Magnetic Field ◽  
Hall Current ◽  
Axial Magnetic Field ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Plasma Radius ◽  
Arc Current ◽  
Field Lines ◽  
The Magnetic Field ◽  
Generally True

Abstract In an arc without external magnetic field the current carrying region is identical with the conducting plasma column. This is no longer generally true if the arc is in an axial magnetic field and if the electrode radius is much smaller than the plasma radius. Radial current components then produce a rotational motion of the plasma and an azimuthal Hall current, and hence electromotive forces which try to suppress the current perpendicular to the magnetic field. In a plasma with finite viscosity the rotation is determined by the Navier-Stokes equation, which is solved here for a homogeneous plasma simultaneously with generalized Ohm's law. The results show that the plasma rotation is always an essential, and often the dominant, mechanism for guiding the arc current parallel to the magnetic field lines.

Sign in / Sign up

Export Citation Format

Share Document