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1.
Charged particle orbits off the equatorial plane of a Kerr black hole in an external electromagnetic field is studied, both
for dipole as well as uniform magnetic field. Particles are found to get trapped by the magnetic field if the initial value
of the parallel velocity is small. Bending of the field lines in the vicinity of the hole and the consequent trapping of the
particles in an otherwise uniform magnetic field indicates the significance of general relativistic effects in such cases. 相似文献
2.
In this paper we have studied the motion of charged particles in a dipole magnetic field on the Schwarzscbild background geometry.
A detailed analysis has been made in the equatorial plane through the study of the effective potential curves. In the case
of positive canonical angular momentum the effective potential has two maxima and two minima giving rise to a well-defined
potential well rear the event horizon. This feature of the effective potential categorises the particle orbits into four classes,
depending on their energies. (i) Particles, coming from infinity with energy less than the absolute maximum ofV
eff, would scatter away after being turned away by the magnetic field. (ii) Whereas those with energies higher than this would
go into the central star seeing no barrier. (iii) Particles initially located within the potential well are naturally trapped,
and they execute Larmor motion in bound gyrating orbits. (iv) and those with initial positions corresponding to the extrema
ofV
eff follow circular orbits which are stable for non-relativistic particles and unstable for relativistic ones. We have also considered
the case of negative canonical angular momentum and found that no trapping in bound orbits occur for this case.
In the case when particles are not confined to the equatorial plane we have found that the particles execute oscillatory motion
between two mirror points if the magnetic field is sufficiently high, but would continuously fall towards the event horizon
otherwise.
An erratum to this article is available at . 相似文献
3.
介绍了一种基于反冲质子法和磁分析技术的氘氚聚变诊断方法, 适用于稳态及脉冲条件下的等离子体温度、燃料密度和中子产额的精确诊断. 设计了小型的原理性装置, 磁分析器使用高性能钕铁硼二极永磁铁, 焦平面上使用CR-39固体径迹探测器或PIN探测器测量质子位置分布. 使用239Pu α 源对磁分析器进行了实验标定, 建立了配套的模拟程序. 利用蒙特卡罗方法模拟分析了装置整体性能, 并在K-400加速器上进行了中子实验研究. 相似文献
4.
We analyze the accretion of charged matter onto a rotating black hole immersed in an aligned dipolar magnetic field. We specialize
to motion in the equatorial plane and calculate the ‘Keplerian’ angular momentum distribution, the marginally stable and marginally
bound orbits, and the efficiency of mass-to-energy conversion as functions of the angular momentum of the black hole and of
the product of the dipole moment and the charge of the infalling matter. Although the detailed results are quite different
from those previously obtained in the case of an uniform magnetic field, the astrophysically relevant results are very similar;
when hydrodynamical accretion is considered, these effects of the magnetic field are always very small. But for test particles
the efficiency can be significantly increased for limited ranges of the parameters. 相似文献
5.
The behavior of the plasma and magnetic and electric fields in the current layer that separates oppositely-directed magnetic fields is studied experimentally. The layer is formed by the interaction of a magnetic dipole with a magnetized plasma flow at Mach numbers lower than 10. 相似文献
6.
The collisionless interaction of an expanding high–energy plasma cloud with a magnetized background plasma in the presence of a dipole magnetic field is examined in the framework of a 2D3V hybrid (kinetic ions and massless fluid electrons) model. The retardation of the plasma cloud and the dynamics of the perturbed electromagnetic fields and the background plasma are studied for high Alfvén–Mach numbers using the particle–in–cellmethod. It is shown that the plasma cloud expands excluding the ambient magnetic field and the background plasma to form a diamagnetic cavity which is accompanied by the generation of a collisionless shock wave. The energy exchange between the plasma cloud and the background plasma is also studied and qualitative agreement with the analytical model suggested previously is obtained (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
采用三维模型,使用混合网格质点法对等离子体入射偶极子磁场产生的磁场膨胀进行数值模拟.在模拟中考虑了高能等离子体注入两种不同类型磁场的情况:等离子体注入没有背景磁场的偶极子磁场和等离子体注入有背景磁场的偶极子磁场.研究表明背景磁场的存在不仅改变了粒子的分布,还改变了磁场膨胀的程度.还研究了注入的高能等离子体的速度对磁场膨胀的影响,结果表明入射的高能等离子体速度越大,磁场膨胀的程度就越大.对于低的入射速度,入射粒子在偶极子磁场中的回旋半径与偶极子磁场的特征长度相比较小,粒子被磁场束缚,对偶极子磁场的影响可以忽
关键词:
网格质点法
磁场膨胀
偶极子磁场 相似文献
8.
Selvarajan V. Rajendran K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(3):543-545
The trajectories of a single charged particle in relation to the cusp axis and cusp plane in a cusped magnetic field are numerically studied. The results show that the particle reflected by the cusp field forms a double helix; i.e., the helix itself makes a helical motion. The location of the reflection point extends well into the injection side of the cusp plane, suggesting that a diverging magnetic field of appropriate geometry may be able to reflect a charged particle. However, the location of the reflection point does not alter the nature of the trajectory 相似文献
9.
In this paper we study the trajectories of charged particles in an electromagnetic field superimposed on the Kerr background.
The electromagnetic fields considered are of two types: (i) a dipole magnetic field with an associated quadrupole electric
field, (ii) a uniform magnetic field. The contribution of the background geometry to the electromagnetic field is taken through
the solutions of Petterson and Wald respectively. The effective potential is studied in detail for ther-motion of the particles in the equatorial plane and the orbits are obtained. The most interesting aspect of the study is
the illustration of the effect of inertial frame dragging due to the rotation of the central star. This appears through the
existence of nongyrating bound orbits at and inside the ergo surface. The presence of the magnetic field seems to increase
the range of stable orbits, as was found in a previous study involving the Schwarzschild background. 相似文献
10.
We investigate the ratio of spin precession frequency to orbital frequency for a spinning charged particle confined to circular
orbit in the equatorial plane of a compact object, with a uniform magnetic field, as described by the Wald and the Ernst potentials.
In order to see the difference in behaviours for particles with differentg values we consider the cases of electron and proton separately. 相似文献
11.
An algorithm for computer simulation of images obtained by magnetic force microscopy (MFM) is suggested. It is based on the Brown formalism and takes into account the shapes and the magnetic properties of the MFM tip and sample studied. The robustness and efficiency of the algorithm are tested by simulating the MFM image of a point magnetic dipole for the case where the tip is approximated by a nonmagnetic truncated cone covered by a thin uniformly magnetized layer. From the computer simulation of the MFM images of the dipole, the optimum parameters of the MFM probe are obtained. 相似文献
12.
Forced oscillations excited by a radial magnetic dipole in a dielectric hemisphere (resonator) placed on a perfectly conducting
plane are studied. It is shown that the dipole excites H modes. When the dipole radiation frequency equals the eigenfrequency of the resonator, an amplitude resonance is observed
in the spectrum. The excitation efficiency is high when the magnetic dipole is placed at the maximum of the radial field component
of the resonator’s eigenmode. 相似文献
13.
A dynamics of the entanglement under an environmental influence is modelled by a bound state composed of two heavy particles
interacting with a strong laser. Adopting the semiclassical attitude, a trajectory of the bound state’s center-of-mass is
found from the Newton equations solved beyond the dipole approximation and taking into account the magnetic field effect.
At the same time the dynamics of constituent spins under the laser coupling is studied quantum mechanically solving the nonrelativistic
von Neumann equation with the effective Hamiltonian determined by the bound state’s classical trajectory. Based on the solution,
the effects of an intense linearly polarized monochromatic plane wave on the precession of entangled spins are discussed for
a specific kind of mixed initial states including a family of maximally entangled Werner states.
The text was submitted by the authors in English. 相似文献
14.
We have investigated mainly the influences of magnetic particle–particle interactions on the orientational distribution and viscosity of a semi-dense dispersion, which is composed of rod-like particles with a magnetic moment magnetized normal to the particle axis. In addition, the influences of the magnetic field strength, shear rate, and random forces on the orientational distribution and rheological properties have been clarified. The mean field approximation has been applied to take into account magnetic interactions between rod-like particles. The basic equation of the orientational distribution function has been derived from the balance of torques and solved by the numerical analysis method. The results obtained here are summarized as follows. For a strong magnetic field, the rotational motion of the rod-like particle is restricted in a plane normal to the shearing plane since the magnetic moment of the particle is restricted in the magnetic field direction. Under circumstances of a very strong magnetic interaction between particles, the magnetic moment is strongly restricted in the magnetic field direction, so that the particle has a tendency to incline in the flow direction with the magnetic moment pointing to the magnetic field direction. For a strong shear flow, a directional characteristic of rod-like particles is enhanced, and this leads to a more significant one-peak-type distribution of the orientational distribution function. Magnetic interactions between particles do not contribute to the increase in the viscosity because the mean-field vector has only a component along the magnetic field direction. 相似文献
15.
V. L. Mironov O. L. Yermolaeva 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2007,1(4):466-470
The interaction of a magnetic vortex in a circular ferromagnetic nanoparticle with the probe field of a magnetic force microscope (MFM) is theoretically investigated. In the calculations, the probe field is approximated by the point dipole field. The rigid magnetic vortex model is used to describe the vortex state of magnetization. It is found that the effect of the probe field on the rigid magnetic vortex shell is similar to the effect of a uniform magnetic field parallel to the particle plane. The effect of the Z component of the probe field on the core of the vortex results in mutual probe-vortex attraction or repulsion. It is shown that the magnetization direction of the core of the vortex in the MFM probe field can be changed without a change in the shell vorticity direction. 相似文献
16.
The subject of discussion is calibration of the tip of a magnetic force microscope using the field of a ring-shaped current loop. To calculate the calibration parameters, the magnetic contribution from the extended tip of the probe in the field of the current loop to the rigidity of the cantilever is approximated by the contribution from a point magnetic dipole and magnetic “charge” in terms of the theoretical model adopted. Three simplified models of the conic tip (with a sharpened, blunted, and rounded top) are considered. The calculated dependences of the effective calibration parameters on the radius of the current loop are compared with experimental data. It is found that the model of a uniformly magnetized tip in the form of a blunted cone provides the best fit to the experiment. The calculation results may be helpful in simulating images obtained with a magnetic force microscope and numerically testing magnetic objects. 相似文献
17.
18.
Bao-Liang Qian 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1999,27(6):1578-1581
An exact solution is found for the relativistic equation of motion of a charged particle driven by a circularly polarized electromagnetic wave and a constant magnetic field. The explicit expressions of particle position and velocity are obtained for certain initial conditions. The results are of interest to the interaction of the high-power laser with the magnetized plasma, electromagnetically pumped free-electron laser with a guide magnetic field, propagation of electromagnetic wave signals through a re-entry plasma sheath in the presence of a strong magnetic field, and magnetic confinement plasmas 相似文献
19.
In this paper, the properties of extraordinary mode for two types of three-dimensional magnetized plasma photonic crystals (3D MPPCs) composed of homogeneous dielectric and magnetized plasma with diamond lattices are theoretically investigated for electromagnetic (EM) wave based on a modified plane wave expansion (PWE) method, as Voigt effects are considered. As EM wave propagates in such 3D MPPCs, the EM wave can be divided in two modes due to the influence of Lorentz force. One is named extraordinary mode and another is ordinary mode. The equations for calculating the dispersive relationships for extraordinary mode as propagating through two types of structures (dielectric spheres immersed in magnetized plasma background or vice versa), are theoretically deduced. The influences of dielectric constant of dielectric, plasma collision frequency, filling factor, the external magnetic field and plasma frequency on the properties of extraordinary mode for both types of MPPCs are investigated in detail, respectively, and some corresponding physical explanations are also given. From the numerical results, it has been shown that not only the locations but also bandwidths and relative bandwidths of the photonic band gaps obtained by extraordinary mode for both types of 3D MPPCs can be manipulated by plasma frequency, filling factor, the external magnetic field and the relative dielectric constant of dielectric, respectively. However, the plasma collision frequency has no effect on the frequency ranges and relative bandwidths of PBGs for two types of 3D MPPCs. The locations of flatbands regions cannot be tuned by any parameters except for plasma frequency and the external magnetic field. 相似文献
20.
A twistor Hamiltonian formulation is given for describing the scattering of a massive particle with spin by a plane impulsive gravitational wave and of a massive particle with spin and charge by a plane impulsive electromagnetic wave. As a Taylor series in the spin of the particle, the expressions obtained agree with the Papapetrou equations and the magnetic dipole force law, respectively, to first order in the spin. 相似文献