scholarly journals Modeling the influence of magnetospheric heat fluxes on the electron temperature in the subauroral ionosphere

2017 ◽  
Vol 3 (2) ◽  
pp. 54-57
Author(s):  
Артем Гололобов ◽  
Artem Gololobov ◽  
Иннокентий Голиков ◽  
Innokentiy Golikov ◽  
Илья Варламов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Temperature ◽  
Heat Fluxes ◽  
Winter Period ◽  
Time Interval ◽  
Geomagnetic Disturbances ◽  
F Region ◽  
Condi Tions ◽  
Field Lines ◽  
Heat Inflow

We present results of modeling of the electron temperature distribution in the F region of the subauroral ionosphere for different helio-geomagnetic conditions with consideration for magnetospheric heat fluxes. It is shown that under quiet geomagnetic condi-tions during a winter period in the dawn and dusk sec-tors “hot” zones with a higher electron temperature are formed, and under disturbed geomagnetic conditions an annular “hot” region is formed in a time interval 04–06 UT as a result of heat inflow from Earth’s magnetosphere along magnetic field lines. The analysis of the DE-2 satellite data demonstrates that such zones can be formed during geomagnetic disturbances.

scholarly journals Modeling the influence of magnetospheric heat fluxes on the electron temperature in the subauroral ionosphere

2017 ◽  
Vol 3 (2) ◽  
pp. 51-53
Author(s):  
Артем Гололобов ◽  
Artem Gololobov ◽  
Иннокентий Голиков ◽  
Innokentiy Golikov ◽  
Илья Варламов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Temperature ◽  
Heat Fluxes ◽  
Winter Period ◽  
Time Interval ◽  
Geomagnetic Disturbances ◽  
F Region ◽  
Condi Tions ◽  
Field Lines ◽  
Heat Inflow

We present results of modeling of the electron temperature distribution in the F region of the subauroral ionosphere for different helio-geomagnetic conditions with consideration for magnetospheric heat fluxes. It is shown that under quiet geomagnetic condi-tions during a winter period in the dawn and dusk sec-tors “hot” zones with a higher electron temperature are formed, and under disturbed geomagnetic conditions an annular “hot” region is formed in a time interval 04–06 UT as a result of heat inflow from Earth’s magnetosphere along magnetic field lines. The analysis of the DE-2 satellite data demonstrates that such zones can be formed during geomagnetic disturbances.

Ionospheric heating in the F -region

1964 ◽  
Vol 281 (1384) ◽  
pp. 140-149 ◽  
Keyword(s):  
Electron Temperature ◽  
Energy Input ◽  
Particle Flux ◽  
Electron Interaction ◽  
Ion Temperature ◽  
Ionospheric Heating ◽  
F Region ◽  
Field Lines ◽  
Photo Ionization ◽  
Made In

Measurements of electron temperature made in Ariel I have been analyzed to calculate the ionospheric energy input required to maintain the electron temperature above the ion temperature. The results are found to be consistent with the energy input due to photo-ionization in the daytime, provided that allowance is made for the effects of the escaping flux of photoelectrons spiralling upwards along the geomagnetic field lines which impartenergy to the ionosphere by electron-electron interaction. However, it is found that during the night an energy input of particle origin is observed, a close agreement being found between the distribution of energy input and that of the fluxes of low-energy particles observed by Savenko, Shavrin & Pisavenko 1963. The particle flux contributes less than 30% to the heat input in the daytime and its diurnal variation is small.

The effect of thermal anisotropy on the propagation of whistler waves in mixed hot-cold electron plasmas

1983 ◽  
Vol 30 (2) ◽  
pp. 291-301 ◽  
Author(s):  
Hiromitsu Hamabata
Keyword(s):  
Magnetic Field ◽  
Electron Temperature ◽  
Static Magnetic Field ◽  
Distribution Functions ◽  
Heat Fluxes ◽  
Temperature Anisotropy ◽  
Whistler Waves ◽  
First Order ◽  
Thermal Anisotropy ◽  
Cold Electrons

The first-order CGL fluid equations for electrons including the first-order heat fluxes are applied to the propagation of whistler waves. The dispersion relation of whistler waves is derived for two types of equilibrium electron distribution functions with cold and hot components. The effect of electron temperature anisotropy and the existence of cold electrons on the field-aligned propagation of whistler waves is analysed. It is shown that the electron temperature anisotropy intensifies the tendency of whistler waves to follow the lines of force of static magnetic field, that the existence of cold electrons in an anisotropic plasma further intensifies this tendency, and that under certain conditions the waves propagate only along the static magnetic field.

scholarly journals Flying through a dawn storm: a multi-instrument study of the traversal of a dawn storm by Juno on February 7th 2018

2020 ◽  
Author(s):  
Bertrand Bonfond ◽  
Ruilong Guo ◽  
Zhonghua Yao ◽  
Grodent Denis ◽  
Jean-Claude Gérard ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Remote Sensing ◽  
Time Interval ◽  
Sharp Transition ◽  
Electrons And Ions ◽  
Observation Sequence ◽  
Field Lines ◽  
The Magnetic Field ◽  
Dawn Sector

<p class="western" align="left">On February 7th 2018, during Juno’s 11th perijove observation sequence, Juno’s ultraviolet spectrograph (Juno-UVS) unveiled the development of a dawn storm in Jupiter's aurorae. These auroral events consist of spectacular brightenings of the midnight to dawn sector of the main emissions at Jupiter. At the end of the sequence, Juno crossed the magnetic field lines connected to this dawn storm, unraveling some of the processes giving rise to these spectacular events. <br />All in situ instruments detected a sharp transition as the spacecraft entered the dawn storm at an altitude of approximately 5RJ in the southern hemisphere. The particle fluxes detected by the JADE and JEDI instruments, including electrons and ions, increased dramatically. A strong flux of penetrating radiation was also detected by the UVS instrument. The Alfvén waves spectrograms derived from the MAG instrument also show a clear transition between a quiet and an extremely active regime as the spacecraft entered the dawn storm. Furthermore, the orientation of the magnetic field showed a very strong perturbation, associated with intense currents. And, finally, intense bKOM emissions were also observed during this time interval. Combined with the remote sensing observations of the aurora, these datasets strongly suggest that Juno witnessed a strong magnetospheric reconfiguration that started in the magneto-tail and then evolved toward dawn as the planet rotated.</p>

The development of magnetic field line wander in gyrokinetic plasma turbulence: dependence on amplitude of turbulence

2017 ◽  
Vol 83 (3) ◽  
Author(s):  
Sofiane Bourouaine ◽  
Gregory G. Howes
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Magnetic Field Line ◽  
Plasma Turbulence ◽  
Turbulent Plasma ◽  
Nonlinearity Parameter ◽  
Time Interval ◽  
Weak Turbulence ◽  
Field Lines ◽  
The Magnetic Field

The dynamics of a turbulent plasma not only manifests the transport of energy from large to small scales, but also can lead to a tangling of the magnetic field that threads through the plasma. The resulting magnetic field line wander can have a large impact on a number of other important processes, such as the propagation of energetic particles through the turbulent plasma. Here we explore the saturation of the turbulent cascade, the development of stochasticity due to turbulent tangling of the magnetic field lines and the separation of field lines through the turbulent dynamics using nonlinear gyrokinetic simulations of weakly collisional plasma turbulence, relevant to many turbulent space and astrophysical plasma environments. We determine the characteristic time $t_{2}$ for the saturation of the turbulent perpendicular magnetic energy spectrum. We find that the turbulent magnetic field becomes completely stochastic at time $t\lesssim t_{2}$ for strong turbulence, and at $t\gtrsim t_{2}$ for weak turbulence. However, when the nonlinearity parameter of the turbulence, a dimensionless measure of the amplitude of the turbulence, reaches a threshold value (within the regime of weak turbulence) the magnetic field stochasticity does not fully develop, at least within the evolution time interval $t_{2}<t\leqslant 13t_{2}$. Finally, we quantify the mean square displacement of magnetic field lines in the turbulent magnetic field with a functional form $\langle (\unicode[STIX]{x1D6FF}r)^{2}\rangle =A(z/L_{\Vert })^{p}$ ($L_{\Vert }$ is the correlation length parallel to the magnetic background field $\boldsymbol{B}_{\mathbf{0}}$, $z$ is the distance along $\boldsymbol{B}_{\mathbf{0}}$ direction), providing functional forms of the amplitude coefficient $A$ and power-law exponent $p$ as a function of the nonlinearity parameter.

scholarly journals Electron temperature of the solar wind

2020 ◽  
Vol 117 (17) ◽  
pp. 9232-9240
Author(s):  
Stanislav Boldyrev ◽  
Cary Forest ◽  
Jan Egedal
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Electron Temperature ◽  
Magnetic Moments ◽  
Collisionless Plasma ◽  
Background Plasma ◽  
Magnetic Flux Tube ◽  
Thermal Source ◽  
Field Lines ◽  
Inner Heliosphere

Solar wind provides an example of a weakly collisional plasma expanding from a thermal source in the presence of spatially diverging magnetic-field lines. Observations show that in the inner heliosphere, the electron temperature declines with the distance approximately as Te(r)∼r−0.3…r−0.7, which is significantly slower than the adiabatic expansion law ∼r−4/3. Motivated by such observations, we propose a kinetic theory that addresses the nonadiabatic evolution of a nearly collisionless plasma expanding from a central thermal source. We concentrate on the dynamics of energetic electrons propagating along a radially diverging magnetic-flux tube. Due to conservation of their magnetic moments, the electrons form a beam collimated along the magnetic-field lines. Due to weak energy exchange with the background plasma, the beam population slowly loses its energy and heats the background plasma. We propose that no matter how weak the collisions are, at large enough distances from the source a universal regime of expansion is established where the electron temperature declines as Te(r)∝r−2/5. This is close to the observed scaling of the electron temperature in the inner heliosphere. Our first-principle kinetic derivation may thus provide an explanation for the slower-than-adiabatic temperature decline in the solar wind. More broadly, it may be useful for describing magnetized collisionless winds from G-type stars.

Stochastic magnetic field lines diffusion in a toroidal configuration (Tokamak)

2000 ◽  
Vol 12 (2) ◽  
pp. 145-153 ◽  
Author(s):  
R. Tabet ◽  
H. Imrane ◽  
D. Saifaoui ◽  
A. Dezairi ◽  
F. Miskane
Keyword(s):  
Magnetic Field ◽  
Field Lines ◽  
Stochastic Magnetic Field

Exact nonlinear wave solutions of the incompressible magnetohydrodynamic equations in a sheared magnetic field

1990 ◽  
Vol 44 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Hiromitsu Hamabata
Keyword(s):  
Magnetic Field ◽  
Incompressible Fluid ◽  
Large Amplitude ◽  
Uniform Magnetic Field ◽  
Magnetohydrodynamic Equations ◽  
Wave Solutions ◽  
Field Lines ◽  
Incompressible Magnetohydrodynamic Equations ◽  
Physical Quantities ◽  
Nonlinear Wave Solutions

Exact wave solutions of the nonlinear jnagnetohydrodynamic equations for a highly conducting incompressible fluid are obtained for the cases where the physical quantities are independent of one Cartesian co-ordina.te and for where they vary three-dimensionally but both the streamlines and magnetic field lines lie in parallel planes. It is shown that there is a class of exact wave solutions with large amplitude propagating in a straight but non-uniform magnetic field with constant or non-uniform velocity.

scholarly journals Magnetic nulls in interacting dipolar fields

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Todd Elder ◽  
Allen H. Boozer
Keyword(s):  
Magnetic Field ◽  
Current Density ◽  
Magnetic Flux Tube ◽  
Electron Inertia ◽  
Characteristic Spatial Scale ◽  
Field Lines ◽  
Dipolar Fields ◽  
Time Required ◽  
Magnetic Null ◽  
The Magnetic Field

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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