Electron-inertia effects on magnetic field reconnection driven by perturbations on boundaries

The prominence of nulls in reconnection theory is due to the expected singular current density and the indeterminacy of field lines at a magnetic null. Electron inertia changes the implications of both features. Magnetic field lines are distinguishable only when their distance of closest approach exceeds a distance $\varDelta _d$ . Electron inertia ensures $\varDelta _d\gtrsim c/\omega _{pe}$ . The lines that lie within a magnetic flux tube of radius $\varDelta _d$ at the place where the field strength $B$ is strongest are fundamentally indistinguishable. If the tube, somewhere along its length, encloses a point where $B=0$ vanishes, then distinguishable lines come no closer to the null than $\approx (a^2c/\omega _{pe})^{1/3}$ , where $a$ is a characteristic spatial scale of the magnetic field. The behaviour of the magnetic field lines in the presence of nulls is studied for a dipole embedded in a spatially constant magnetic field. In addition to the implications of distinguishability, a constraint on the current density at a null is obtained, and the time required for thin current sheets to arise is derived.

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Effect of electron inertia on radiative instability of rotating two-component gaseous plasma

Canadian Journal of Physics ◽

10.1139/p2012-098 ◽

2012 ◽

Vol 90 (12) ◽

pp. 1209-1221 ◽

Cited By ~ 4

Author(s):

A.K. Patidar ◽

R.K. Pensia ◽

V. Shrivastava

Keyword(s):

Magnetic Field ◽

Thermal Conductivity ◽

Growth Rate ◽

Electrical Resistivity ◽

Heat Loss ◽

Loss Function ◽

Mode Analysis ◽

Electron Inertia ◽

Radiative Instability ◽

Jeans Criterion

The problem of radiative instability of homogeneous rotating partially ionized plasma incorporating viscosity, porosity, and electron inertia in the presence of a magnetic field is investigated. A general dispersion relation is obtained using normal mode analysis with the help of relevant linearized perturbation equations of the problem. The modified Jeans criterion of instability is obtained. The conditions of Jeans instabilities are discussed in the different cases of interest. It is found that the simultaneous effect of viscosity, rotation, finite conductivity, and porosity of the medium does not essentially change the Jeans criterion of instability. It is also found that the presence of arbitrary radiative heat-loss function and thermal conductivity modified the conditions of Jeans instability for longitudinal propagation. It is found that, for longitudinal propagation, the conditions of radiative instability are independent of magnetic field, viscosity, rotation, finite electrical resistivity, and electron inertia, but for the transverse mode of propagation it depends upon finite electrical resistivity and strength of magnetic field and is independent of viscosity, electron inertia, and rotation. From the curves we find that viscosity has a stabilizing effect on the growth rate of instability but the thermal conductivity and density-dependent heat-loss function has a destabilizing effect on the instability growth rate.

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Models to Illustrate Gyromagnetic and Electron-Inertia Effects

American Journal of Physics ◽

10.1119/1.1991153 ◽

1937 ◽

Vol 5 (1) ◽

pp. 1-6

Author(s):

S. J. Barnett

Keyword(s):

Inertia Effects ◽

Electron Inertia

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The Magnetic Fields of Pulsars

Symposium - International Astronomical Union ◽

10.1017/s0074180900236292 ◽

1974 ◽

Vol 64 ◽

pp. 187-187

Author(s):

D. M. Sedrakian

Keyword(s):

Magnetic Field ◽

Angular Velocity ◽

Magnetic Fields ◽

Relative Motion ◽

Kinematic Viscosity ◽

Charged Particles ◽

Normal Fluid ◽

Inertia Effects ◽

Generation Mechanisms ◽

Image Position

Two generation mechanisms of magnetic fields in pulsars are considered.If the temperature of a star is more than 108K, the star consists of a normal fluid of neutrons, protons and electrons. Because the angular velocity of pulsars is not constant dω/dt ≠0, inertia effects can occur, and generate magnetic fields through the relative motion of charged particles with different masses. The kinematic viscosity of electrons is 30 times larger than that of protons; hence electrons move with the crust, but the proton-neutron fluid will move relative to the electrons. The magnetic momentum can be calculated by the following formula where Meff = Mp + Mn(Nn/Np), R = radius of the star, σ = conductivity. For typical neutron stars we have dω/dt~ 10-8 s-2, R~106 cm, σ~1029 s-1 and we get a magnetic field of the order of 1010 G.

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Kinetic Alfvén solitons in a low-beta plasma

Journal of Plasma Physics ◽

10.1017/s0022377896004849 ◽

1997 ◽

Vol 57 (2) ◽

pp. 235-245 ◽

Cited By ~ 4

Author(s):

B. C. KALITA ◽

R. P. BHATTA

Keyword(s):

Magnetic Field ◽

Mach Number ◽

Solitary Waves ◽

Magnetic Pressure ◽

Hot Electrons ◽

Mass Ratio ◽

Ion Motion ◽

Electron Inertia ◽

Theoretical Investigations ◽

The Magnetic Field

Kinetic Alfvén solitons with hot electrons and finite electron inertia in a low-beta (β=8πn0T/B2G, the ratio of the kinetic to the magnetic pressure) plasma is studied analytically, with the ion motion being considered dominant through the polarization drift. Both compressive and rarefactive kinetic Alfvén solitons are found to exist within a definite range of kz (the direction of propagation of the kinetic Alfvén solitary waves with respect to the direction of the magnetic field) for each pair of assigned values of β and M (Mach number). Unlike in previous theoretical investigations, β appears as an explicit parameter for the kinetic Alfvén solitons in this case. In addition, consideration of the electron pressure gradient is found to suppress the speed of both the Alfvén solitons considerably for A (=2QM2/βk2z, with Q the electron-to-ion mass ratio) less than unity.

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