Effect Of Inhomogeneous Magnetic Field Research Articles

Effect of inhomogeneous magnetic field on blue core in Ar helicon plasma

The effect of the inhomogeneous magnetic field on blue core phenomena in helicon plasma is investigated in this work. The permanent magnets (PMs) are used to provide the magnetic field required for generation of helicon plasma, and three different types of the inhomogeneous magnetic field are constructed by changing the permanent magnets positions, which are PM-top/bottom, PM-top, and PM-bottom, respectively. The maximum magnetic field strengths in these three types of inhomogeneous magnetic fields are at both ends (case A), at the upper end (case B), and at the lower end (case C) of the discharge tube, respectively. Nikon camera, an intensified charge coupled device, optical emission spectrometer (OES), and Langmuir probe are used to diagnose the blue core phenomenon in helicon plasma. The electronic excitation temperature is calculated based on optical emission lines captured by OES. Helicon wave discharge is affirmed by mode transition with three discharge stages corresponding to E-, H- and W-modes, respectively. The blue core could occur in the maximum magnetic field strengths located at both ends at around 200 W, at the upper end at around 300 W, and at the lower end at around 400 W. The formation of blue core in the present work can be attributed to the non-uniformity of the inhomogeneous magnetic field. Meanwhile, the radial distribution of plasma density and electron temperature in blue core is different. The plasma density still maintains the on-axis peak, and electron temperature transforms from on-axis peak to off-axis peak due to the skin effect.

Observational Evidence for Whistler Mode Waves Guided/Ducted by the Inner and Outer Edges of the Plasmapause

AbstractWe present observational support for whistler mode waves guidance by the plasmapause gradients based on a case study and statistical analyses. Due to the combined effects of inhomogeneous magnetic fields and plasma densities, whistler mode waves near the inner edge of plasmapause (plasmasphere side) will be guided by a high density duct‐like (HDD) gradient, and tend to have very small wave normal angles (WNAs ≤ 20°) relative to the ambient magnetic field,B0. In contrast, whistler mode waves near the outer edge of the plasmapause (plasmatrough side) guided by a low density duct‐like (LDD) gradient, tend to have quite large WNAs (≥∼60°). Statistical analyses emphasize these remarkably different properties of waves in the plasmapause gradients. The results indicate that the wave ducting effects at the plasmapause may lead to unusual and anomalous energetic pitch angle scattering.

Oscillations of EPR Signals Accompanying Belousov–Zhabotinsky Reaction

Periodical transformation of ferroin to ferriin is accompanied by changes in magnetic properties of liquids during Belousov–Zhabotinsky (BZ) reaction malonic acid, sodium bromide, sodium bromate, ferroin, and sulfuric acid. Instead of the earlier studied oscillation of microwave conductivity accompanying an oscillating reaction, we propose a flash technique to interrupt the BZ reaction by rapid freezing. Rapid cooling of a solution during chemical oscillations results in a frozen system with a fixed concentration of paramagnetic centers Fe3+. EPR spectrum recorded at different stages of the interrupted reaction corresponds to the exact concentration of the ferroin and ferriin components. Following unfreezing unblocks the BZ reaction, and oscillations are still observed. A simulated spectrum allows one to distinguish two groups of Fe3+ ions of different symmetries. The obtained results are important to explain the earlier observed effect of inhomogeneous magnetic field on BZ reaction front velocity.

The Propagation of Flame Fronts through Inhomogeneously Magnetized Plasma

Abstract The effects of inhomogeneous magnetic fields on the propagation of magnetohydrodynamical (MHD) laminar flame fronts are investigated. This investigation is motivated by the occurrence of magnetized thermonuclear combustion in astrophysical systems. Magnetized thermonuclear burning occurs on the surfaces of neutron stars during Type I X-ray bursts, within the interiors of white dwarfs during SNe Ia, and during classical novae. Thermonuclear flames that propagate in these systems are expected to travel through inhomogeneous magnetic fields. We present the results of a series of 1.5-dimensional numerical simulations of magnetized flame propagation. A simplified flame model is used with one-step Arrhenius kinetics, an ideal gas equation of state, and constant thermal conductivity coefficients. Although idealized, the model allows for the opportunity to study the physics of the problem without the complexities of the nuclear kinetics of thermonuclear burning. We simulate the propagation of laminar flames through inhomogeneous magnetic media. A changing magnetic medium significantly alters the structure of the flame through the generation of an electric current. The electric current rotates the direction of the magnetic field within the flame and produces strong shear flows. Furthermore, for flames that conduct heat anisotropically and that propagate at an angle 0 < ψ ≲ π/2 to the magnetic field, the flame speed increases due to the nonuniform magnetic field. Naturally occurring flames in astrophysical systems may experience similar changes to their structure and speed that would influence the observational properties of these systems.

Effect of inhomogeneous magnetic field on plasma generation in a low magnetic field helicon discharge

Efficient plasma production by a helicon wave in a nonuniform magnetic field near the antenna center is being reported here. Experiments are carried out with different nonuniformities of the magnetic field near the antenna keeping the magnetic field at the center of the antenna <100 G. Coupling efficiencies are studied by measuring the antenna current with and without plasma. Plasma production efficiencies are also estimated in all the different magnetic field topologies. It has been observed that the coupling efficiency increases with the magnetic field nonuniformity. Observation of the beat wave in the axial variation of the axial wave magnetic field suggests the presence of different radial wavemodes. Measurements of the axial wavenumber along with the estimation of the radial wavenumber suggest wave propagation near the resonance cone causing more absorption. It is found that the density obtained by introducing a nonuniform magnetic field results in a higher density than the conventional helicon. Finally, the wavelength is measured for the nonuniform magnetic field near the antenna when the magnetic field is kept at 25 G and 50 G at the antenna center. For the 25 G case, the measured axial wavelength is found to be twice the length of the antenna. This suggests that the half wavelength antenna excites the full wavelength helicon wave. However, in the 50 G case, the measured wavelength is shown to be approximately equal to the antenna length.

Magnetomigration of Rare-Earth Ions Triggered by Concentration Gradients.

Mach-Zehnder interferometry was applied to explore the effects of inhomogeneous magnetic fields on the mobility of rare-earth ions in aqueous solutions. No migration of ions was observed in a thermodynamically closed system when a homogeneous solution was subjected to a magnetic field gradient alone. However, magnetomigration could be triggered by a concentration gradient of the rare-earth ions in the solution. When a concentration gradient was introduced in the sample by solvent evaporation, consistent migration of paramagnetic Dy3+ ions from the bulk solution to regions with stronger magnetic fields was observed. By contrast, no movement was detected for diamagnetic Y3+ ions in the presence of a concentration gradient.

Влияние неоднородного магнитного поля на физические свойства металлосодержащих полимерных композитов

Влияние неоднородного магнитного поля на физические свойства металлосодержащих полимерных композитов

Rayleigh-Taylor instability in non-uniform magnetized rotating strongly coupled viscoelastic fluid

The Rayleigh-Taylor instability (RTI) in an incompressible strongly coupled viscoelastic fluid is investigated considering the effects of inhomogeneous magnetic field, density gradient, and uniform rotation. The generalized hydrodynamic equations have been formulated, and linear dispersion relation is derived taking appropriate density and magnetic field profiles for the considered system. The gravity induced stable and unstable configurations of RTI are analyzed in hydrodynamic and kinetic limits. In the kinetic limit, shear wave modified dispersion relation and the condition of RTI are derived in terms of magnetic-viscoelastic Mach number and viscoelastic Froude number. The criteria of RTI and critical wavenumber for the growth of RTI to be unstable are estimated numerically for white dwarf and inertial confinement fusion target. It is observed that magnetic field, rotation, and viscoelastic effects play a significant role in the suppression of RTI in these systems. The stabilizing influence of magnetic field, rotation, and magnetic-viscoelastic Mach number while the destabilizing influence of viscoelastic Froude on the growth rate of RTI number is observed graphically. The growth rate of RTI decreases faster in kinetic limit as compared to the hydrodynamic limit.

Effects of inhomogeneous magnetic field and magnetic impurity on the quantum correlation of spin-1 system

We investigate the effects of inhomogeneous magnetic field and magnetic impurity on the quantum correlation in spin-1 system by means of negativity and measurement-induced disturbance. Results show that the increase of the inhomogeneous magnetic field not only decreases entanglement, but also can induce the entanglement, and increases the value of critical nonlinear coupling Kc. The critical magnetic field for measurement-induced disturbance is higher than that for negativity, and the measurement-induced disturbance (MID) will not disappear with the decrease of nonlinear coupling |K|, so it can reveal all the properties of quantum correlation. Results also show that the effects of different magnetic impurity on MID are independent of each other. Under the magnetic impurity, the entanglement exists only if the couplings |J| are less than the nonlinear couplings |K|, while there will be the MID when the couplings |J| are greater than the nonlinear couplings |K|. It is just the minimum point for MID when |J| equals to |K|. Moreover, the size of the Chain will influence the quantum correlation also.

Effects of inhomogeneous magnetic fields and different Dzyaloshinskii-Moriya interaction on entanglement and teleportation in a two-qubit Heisenberg XYZ chain

In this paper we calculate the thermal entanglement and teleportation in a two-qubit Heisenberg XYZ chain with the different Dzyaloshinskii-Moriya interaction and inhomogeneous magnetic fields. The analytical expressions of the concurrence and the average fidelity are obtained for this model. We have shown that the quantum phase transition occurs in the system and the quantum phase transition point depends on the inhomogeneity of magnetic fields. We compare the x-component Dzyaloshinskii-Moriya interaction with the z-component Dzyaloshinskii-Moriya interaction on the effects of quantum teleportation. It is found that we can take Dzyaloshinskii-Moriya interaction as one of the effective control parameters for the teleportation manipulation.

Swap operation in the presence of Zeeman inhomogeneity in coupled quantum dots

In this paper, we study the effects of inhomogeneous magnetic field on the swap operation, which is a fundamental component to construct universal quantum circuits. The lower bound of the operation fidelity is given. The scheme to perform the ideal swap operation and its square root is investigated. It is shown that the strength of the exchange coupling should satisfy some discrete values.

Thermal quantum discord in Heisenberg XXZ model under different magnetic field conditions

The quantum discord of a two-qubit one-dimonsional Heisenberg XXZ spinchain in thermal equilibrium depends on the temperature T, when subjected to different magnetic fields, with B1 and B2 acting separately on the qubit, is studied in this paper. Four cases are considered here: (1) B1=B2 = 0 (without magnetic field); (2) B1≠0,B2=0 (only one qubit in magnetic field); (3) B1=B2 (homogeneous magnetic field); (4) B1=-B2 (inhomogeneous magnetic field). The similarities and difference between quantum discord and quantum entanglement are calculated and discussed in detail. Results show that the quantum discord is more robust than quantum entanglement against temperature, and the effect of inhomogeneous magnetic field is preferable for the quantum communications and quantum information processing, as compared with the effect of homogeneous magnetic field.

Influence of inhomogeneous magnetic field on the characteristics of very high frequency capacitively coupled plasmas

The effect of inhomogeneous magnetic field on the spatial structure of very high frequency (VHF) plasmas is investigated for different coil configurations, gas pressures, high frequency bias powers, and degrees of electronegativity. The simulation results show that the electron density peaks in the center of the chamber for VHF plasmas due to the standing electromagnetic wave effect. On application of a magnetic field, the density increases near the wafer edge and decreases at the chamber center. The radial magnetic field component is found to limit electron loss to the electrodes and locally enhance the electron density. The axial magnetic field component limits plasma diffusion in the radial direction helping preserve the effect of improved electron confinement by the radial magnetic field. The peak electron density decreases with increasing magnetic field as the plasma moves toward the electrode edge occupying a larger volume. The effect of magnetic field becomes weaker at higher pressure due to the increased electron-neutral collisions which reduce the effectiveness of electron confinement around the magnetic field lines. The impact of magnetic field on plasma profile is somewhat weaker in an electronegative Ar/CF4 plasma because of the presence of less mobile and unmagnetized negative ions.

Effects of inhomogeneous magnetic field on entanglement and teleportation in a two-qubit Heisenberg XXZ chain with intrinsic decoherence

We studied the effects of inhomogeneous magnetic field on entanglement and teleportation in a two-qubit Heisenberg XXZ chain with intrinsic decoherence taken into account. The dependences of the entanglement and fully entangled fraction on the inhomogeneous magnetic fields b and time t are investigated in detail. The contrast between different initial states, including pure and mixed states, is presented.

Effects of inhomogeneous magnetic fields on the electron transport through a quantum-wire system

The electron transport through a quantum-wire system in the presence of inhomogeneous magnetic fields is investigated theoretically. The system consists of two parallel quantum wires coupled by two ballistic windows, while the magnetic fields applied are uniform and equal in the two wires but vanishing in the two coupling windows and everywhere between the wires. Various transmissions of the system are calculated. It is found that the inhomogeneous magnetic fields induce irregular transmission oscillations in the low and moderate magnetic-field regions, and regular ones in the high field region. These transmission oscillations are due to interference between the electron waves traveling through different coupling windows and can be interpreted in terms of a semiclassical model. The Hall resistance of the system is also calculated and is found to show similar regular oscillations at high magnetic fields.

Cyclotron emission from nonuniformly magnetized plasmas.

A new quantitative representation of the generalized Kirchhoff's law relating the emission from each propagating branch to the absorption along the corresponding branch is established, including for the first time the effects of inhomogeneous magnetic fields on cyclotron and synchrotron radiation from mode conversion theory. The concept of optical depth is revised to include effects of reflection and conversion in addition to transmission. Via the use of a variational principle, the source distribution function for the inhomogeneous emitting layer is calculated.

THE KINETIC DRIFT CYCLOTRON LOSS CONE INSTABILITIES IN AN INHOMOGENEOUS MEGNETIC FIELD

The kinetic effects of magnetic drift resonance on the drift cyclotron loss cone instability (DCLC) are studied in detail both analytically and numerically. It is found that the effects of inhomogeneous magnetic field in high β plasmas are important, the kinetic resonance act as a dissipative effect, which can enhance the instability and broaden the unstable region of negative energy DCLC mode. Finite β effects do not play the stabilization role predicted by the theories under the fluid approximation.

Observation of Effects of Inhomogeneous Magnetic Field on Resonance Cone Fields

Observation of Effects of Inhomogeneous Magnetic Field on Resonance Cone Fields

Erythrocytes sedimentation profiles under gravitational field as determined by He-Ne laser: VIII--effect of inhomogeneous magnetic field.

The erythrocytes sedimentation profiles (ESP's) of normal blood, with and without inhomogeneous magnetic field in a glass chamber, are determined. It is observed that the distribution pattern of the erythrocytes in the presence of a magnetic field is significantly different from that of the control sample. These changes in the sedimentation pattern are attributed to the combined effects of the gravitational field and the diamagnetic nature of the erythrocytes, which tend to accelerate or decelerate the cells while passing through the decreasing or increasing magnetic field. The application of the present technique to analyze the sedimentation behavior of the erythrocytes possessing hemoglobin of altered magnetic properties (such as in malaria), with or without altered surface charge, are outlined.

Effect of inhomogeneous magnetic field on physical processes in a gas-discharge positive column

The transverse distribution of the Charged-particle concentration in the positive column of a gas discharge situated in an inhomogeneous magnetic field is obtained; the dependence of the ionization coefficient on the magnitude of the magnetic field is calculated.