scholarly journals Stokes Parameters for Thomson Scattering in Magnetized Plasma

1990 ◽  
Vol 142 ◽  
pp. 93-94
Author(s):  
Chih-Kang Chou ◽  
Hui-Hwa Chen
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Electric Field ◽  
Collisionless Plasma ◽  
Thomson Scattering ◽  
Density Fluctuations ◽  
Magnetized Plasma ◽  
Stokes Parameters ◽  
Retarded Time ◽  
Image Position

The effect of a superstrong magnetic field on neutron stars or white dwarfs is studied for Thomson scattering in a fully ionized collisionless. plasma. The equation of motion for an electron in the presence of both the induced electric field of the plasma and a static uniform external magnetic field is used to determine the acceleration of the electron. The collective plasma effects due to the field and density fluctuations are investigated by using the test-particle picture. The scattering of a photon by a plasma is a function of the acceleration of particles by the electric field of the incident wave and the static external magnetic field Assuming that the electrons are distributed with density the radiation field far from the scattering center is where the delta function indicates that all quantities are to be evaluated at the retarded time and δλ is the angle between the wave vector and the Poynting vector, which is given by

Cross-field plasma acceleration and potential formation induced by electromagnetic waves in a magnetized plasma

2001 ◽  
Vol 66 (3) ◽  
pp. 143-155 ◽  
Author(s):  
R. SUGAYA
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Electric Field ◽  
Electromagnetic Waves ◽  
Collisionless Plasma ◽  
Magnetized Plasma ◽  
Propagating Waves ◽  
Potential Formation ◽  
Dynamo Effect ◽  
The Magnetic Field

A single-particle theory is developed to investigate particle acceleration along and across a magnetic field and the generation of an electric field transverse to the magnetic field induced by electromagnetic waves in a magnetized plasma. The almost perpendicularly propagating waves accelerate particles via their Landau and cyclotron damping, and the ratio of parallel and perpendicular drift velocities vs∥/vd can be proved to be proportional to k∥/k⊥. Simultaneously, an intense cross-field electric field E0 = B0×vd/c is generated via the dynamo effect owing to perpendicular particle acceleration to satisfy the generalized Ohm’s law. This means that this cross-field particle drift in a collisionless plasma is identical to E×B drift. It is verified that the transport equations obtained are exactly equivalent to those derived from the θ-dependent quasilinear velocity-space diffusion equation obtained from the Vlasov–Maxwell equations.

Effect of external magnetic field on lane formation in driven pair-ion plasmas

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Swati Baruah ◽  
U. Sarma ◽  
R. Ganesh
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Coupling Parameter ◽  
Critical Parameters ◽  
Coulomb Coupling ◽  
Lane Formation ◽  
Parameter Values

Lane formation dynamics in externally driven pair-ion plasma (PIP) particles is studied in the presence of external magnetic field using Langevin dynamics (LD) simulation. The phase diagram obtained distinguishing the no-lane and lane states is systematically determined from a study of various Coulomb coupling parameter values. A peculiar lane formation-disintegration parameter space is identified; lane formation area extended to a wide range of Coulomb coupling parameter values is observed before disappearing to a mixed phase. The different phases are identified by calculating the order parameter. This and the critical parameters are calculated directly from LD simulation. The critical electric field strength value above which the lanes are formed distinctly is obtained, and it is observed that in the presence of the external magnetic field, the PIP system requires a higher value of the electric field strength to enter into the lane formation state than that in the absence of the magnetic field. We further find out the critical value of electric field frequency beyond which the system exhibits a transition back to the disordered state and this critical frequency is found as an increasing function of the electric field strength in the presence of an external magnetic field. The movement of the lanes is also observed in a direction perpendicular to that of the applied electric and magnetic field directions, which reveals the existence of the electric field drift in the system under study. We also use an oblique force field as the external driving force, both in the presence and absence of the external magnetic field. The application of this oblique force changes the orientation of the lane structures for different applied oblique angle values.

Particle acceleration by interstellar plasma shock waves in non-uniform background magnetic field

2020 ◽  
Vol 498 (4) ◽  
pp. 5517-5523
Author(s):  
P Rashed-Mohassel ◽  
M Ghorbanalilu
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Shock Waves ◽  
Electric Field ◽  
Background Field ◽  
Magnetized Plasma ◽  
Background Magnetic Field ◽  
Positive Variation ◽  
Uniform Background ◽  
Plasma Shock

ABSTRACT Particle acceleration by plasma shock waves is investigated for a magnetized plasma cloud propagating in a non-uniform background magnetic field by means of analytical and numerical calculations. The mechanism studied here is mainly, magnetic trapping acceleration (MTA) which is previously investigated for a cloud moving through the uniform interstellar magnetic field (IMF). In this work, the acceleration is studied for a cloud moving in an antiparallel background field with spatial variations along the direction of motion. For negative variation, the cloud moves towards an antiparallel magnetic field with an increasing intensity, the trapped particle moves to locations with higher convective electric field and therefore gains more energy over time. For positive variation, the background field decreases to zero and changes into a parallel field with an increasing intensity. It is concluded that, when the background field vanishes, the MTA mechanism ceases and the particle escapes into the space. This leads to a bouncing acceleration which further increases energy of the gyrating particle. The two processes are followed by a shock drift acceleration, where due to the background magnetic field gradient, the particle drifts along the electric field and gains energy. Although for positive variation, three different mechanisms are involved, energy gain is less than in the case of a uniform background field.

scholarly journals Microstructure of the Galactic Magnetic Field

1958 ◽  
Vol 8 ◽  
pp. 952-954
Author(s):  
K. Serkowski
Keyword(s):  
Magnetic Field ◽  
Position Angle ◽  
Mean Value ◽  
Open Clusters ◽  
Electric Vector ◽  
Stokes Parameters ◽  
Galactic Magnetic Field ◽  
The Mean ◽  
Image Position

The polarization of the stars in open clusters, explained on the basis of the Davis-Greenstein theory, gives some information on the microstructure of the galactic magnetic field.The polarization is most conveniently described by the parameters Q, U, proportional to the Stokes parameters and defined by where p is the amount of polarization, θ is the position angle of the electric vector, and θ̄ is the mean value of θ for the region under consideration.

Quantum Theory of Stokes Parameters for Thomson Scattering in a Magnetised Plasma

1991 ◽  
Vol 9 (2) ◽  
pp. 325-325
Author(s):  
Chih-Kang Chou ◽  
Hui-Hwa Chen
Keyword(s):  
Magnetic Field ◽  
Angular Distribution ◽  
Quantum Theory ◽  
Free Path ◽  
Strong Magnetic Field ◽  
Cross Section ◽  
Mean Free Path ◽  
Thomson Scattering ◽  
Stokes Parameters ◽  
Scattering Process

Extended abstractThomson scattering in pulsar magnetospheres has previously been studied by several authors. The most distinguishing feature is the fact that the super-strong magnetic field (B ~ 1012 G) greatly affects the Thomson scattering process, resulting in resonances in the scattering cross-section (Canuto et al. 1971; Herold 1979; Chou 1986; Daugherty and Harding 1986). The important consequences of these cyclotron resonances are the increase in the photon mean free path in the scattering regions, and strongly affecting the angular distribution, and polarisation properties of the scattered photons (Chou 1986; Chou et al. 1989).

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