scholarly journals Die Bewegung geladener Teilchen im Magnetfeld eines geraden stromdurchflossenen Drahtes

1959 ◽  
Vol 14 (1) ◽  
pp. 47-54 ◽  
Author(s):  
F. Hebtweck
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Charged Particle ◽  
Small Particle ◽  
Numerical Solutions ◽  
Equations Of Motion ◽  
Particle Energy ◽  
Infinite Length ◽  
Electric Line ◽  
The Magnetic Field

The motion of a charged particle in the magnetic field of a straight electric line current of infinite length is investigated. Using the numerical solutions of the equations of motion the drift velocity of the particle along the wire is calculated. For small particle energies it turns out to be in agreement with ALFVÉN'S approximation. Also the limits of the region to which the particle is confined are calculated for different values of the particle energy and its angular momentum.

scholarly journals Ion motion in the current sheet with sheared magnetic field – Part 1: Quasi-adiabatic theory

2013 ◽  
Vol 20 (1) ◽  
pp. 163-178 ◽  
Author(s):  
A. V. Artemyev ◽  
A. I. Neishtadt ◽  
L. M. Zelenyi
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Analytical Description ◽  
Particle Energy ◽  
Tangential Component ◽  
Adiabatic Invariant ◽  
Ion Motion ◽  
Adiabatic Theory ◽  
Fast Oscillations ◽  
The Magnetic Field

Abstract. We present a theory of trapped ion motion in the magnetotail current sheet with a constant dawn–dusk component of the magnetic field. Particle trajectories are described analytically using the quasi-adiabatic invariant corresponding to averaging of fast oscillations around the tangential component of the magnetic field. We consider particle dynamics in the quasi-adiabatic approximation and demonstrate that the principal role is played by large (so called geometrical) jumps of the quasi-adiabatic invariant. These jumps appear due to the current sheet asymmetry related to the presence of the dawn–dusk magnetic field. The analytical description is compared with results of numerical integration. We show that there are four possible regimes of particle motion. Each regime is characterized by certain ranges of values of the dawn–dusk magnetic field and particle energy. We find the critical value of the dawn–dusk magnetic field, where jumps of the quasi-adiabatic invariant vanish.

scholarly journals Nonlinear force-free modeling of magnetic fields in flare-productive active regions

2015 ◽  
Vol 11 (S320) ◽  
pp. 167-174
Author(s):  
M. S. Wheatland ◽  
S. A. Gilchrist
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Boundary Data ◽  
Numerical Solutions ◽  
Free Field ◽  
Active Regions ◽  
Coronal Magnetic Field ◽  
Nonlinear Force ◽  
The Magnetic Field ◽  
Force Free Field

AbstractWe review nonlinear force-free field (NLFFF) modeling of magnetic fields in active regions. The NLFFF model (in which the electric current density is parallel to the magnetic field) is often adopted to describe the coronal magnetic field, and numerical solutions to the model are constructed based on photospheric vector magnetogram boundary data. Comparative tests of NLFFF codes on sets of boundary data have revealed significant problems, in particular associated with the inconsistency of the model and the data. Nevertheless NLFFF modeling is often applied, in particular to flare-productive active regions. We examine the results, and discuss their reliability.

A parallel acquisition charged particle energy analyser using a magnetic field

2016 ◽  
Vol 49 (1) ◽  
pp. 34-46
Author(s):  
C.G.H. Walker ◽  
X. Zha ◽  
M.M. El Gomati
Keyword(s):  
Magnetic Field ◽  
Charged Particle ◽  
Particle Energy ◽  
Parallel Acquisition

Why only a small fraction of quasars are radio loud?

2018 ◽  
Vol 14 (S342) ◽  
pp. 201-204
Author(s):  
Xinwu Cao
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Angular Momentum ◽  
Angular Velocity ◽  
Strong Magnetic Field ◽  
Weak Magnetic Field ◽  
Thin Disk ◽  
Relativistic Jets ◽  
Jet Formation ◽  
The Magnetic Field

AbstractIt is still a mystery why only a small fraction of quasars contain relativistic jets. A strong magnetic field is a necessary ingredient for jet formation. Gas falls from the Bondi radius RB nearly freely to the circularization radius Rc, and a thin accretion disk is formed within Rc We suggest that the external weak magnetic field threading interstellar medium is substantially enhanced in this region, and the magnetic field at Rc can be sufficiently strong to drive outflows from the disk if the angular velocity of the gas is low at RB. In this case, the magnetic field is efficiently dragged in the disk, because most angular momentum of the disk is removed by the outflows that lead to a significantly high radial velocity. The strong magnetic field formed in this way may accelerate jets in the region near the black hole, either by the Blandford-Payne or/and Blandford-Znajek mechanisms. If the angular velocity of the circumnuclear gas is low, the field advection in the thin disk is inefficient, and it will appear as a radio-quiet (RQ) quasar.

scholarly journals Magnetic braking of supermassive stars through winds

2019 ◽  
Vol 623 ◽  
pp. L7 ◽  
Author(s):  
L. Haemmerlé ◽  
G. Meynet
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Formation Process ◽  
Magnetic Coupling ◽  
Rotation Velocity ◽  
Stellar Surface ◽  
Stellar Winds ◽  
Stellar Rotation ◽  
Magnetic Braking ◽  
The Magnetic Field

Context. Supermassive stars (SMSs) are candidates for being progenitors of supermassive quasars at high redshifts. However, their formation process requires strong mechanisms that would be able to extract the angular momentum of the gas that the SMSs accrete. Aims. We investigate under which conditions the magnetic coupling between an accreting SMS and its winds can remove enough angular momentum for accretion to proceed from a Keplerian disc. Methods. We numerically computed the rotational properties of accreting SMSs that rotate at the ΩΓ-limit and estimated the magnetic field that is required to maintain the rotation velocity at this limit using prescriptions from magnetohydrodynamical simulations of stellar winds. Results. We find that a magnetic field of 10 kG at the stellar surface is required to satisfy the constraints on stellar rotation from the ΩΓ-limit. Conclusions. Magnetic coupling between the envelope of SMSs and their winds could allow for SMS formation by accretion from a Keplerian disc, provided the magnetic field is at the upper end of present-day observed stellar fields. Such fields are consistent with primordial origins.

A Proposed Experiment of Direct Detecting of the Vector Potential within Classical Electrodynamics

1997 ◽  
Vol 11 (12) ◽  
pp. 531-540
Author(s):  
V. Onoochin
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Charged Particle ◽  
Vector Potential ◽  
Energy Exchange ◽  
Short Pulse ◽  
Classical Electrodynamics ◽  
Direct Influence ◽  
Ultra Short Pulse ◽  
The Magnetic Field

An experiment within the framework of classical electrodynamics is proposed, to demonstrate Boyer's suggestion of a change in the velocity of a charged particle as it passes close to a solenoid. The moving charge is replaced by an ultra-short pulse (USP), whose characteristics should depend on the current in the coil. This dependence results from the exchange of energy between the electromagnetic field of the pulse and the magnetic field within the solenoid. This energy exchange could only be explained, by assuming that the vector potential of the solenoid has a direct influence on the pulse.

scholarly journals Magnetorotational supernovae with different equations of state

2011 ◽  
Vol 7 (S279) ◽  
pp. 357-358
Author(s):  
Sergey G. Moiseenko ◽  
Gennady S. Bisnovatyi-Kogan
Keyword(s):  
Magnetic Field ◽  
Shock Wave ◽  
Angular Momentum ◽  
Differential Rotation ◽  
Equations Of State ◽  
Supernova Explosion ◽  
Explosion Energy ◽  
Iron Core ◽  
Wave Forms ◽  
The Magnetic Field

AbstractWe present results of the simulation of a magneto-rotational supernova explosion. We show that, due to the differential rotation of the collapsing iron core, the magnetic field increases with time. The magnetic field transfers angular momentum and a MHD shock wave forms. This shock wave produces the supernova explosion. The explosion energy computed in our simulations is 0.5-2.5 ċ 1051erg. We used two different equations of state for the simulations. The results are rather similar.

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