Dynamos of giant planets

2006 ◽  
Vol 2 (S239) ◽  
pp. 467-474
Author(s):  
F. H. Busse ◽  
R. Simitev
Keyword(s):  
Magnetic Field ◽  
Recent Progress ◽  
Giant Planets ◽  
Magnetic Field Generation ◽  
Ohmic Dissipation ◽  
Field Generation ◽  
Spherical Fluid ◽  
The Magnetic Field ◽  
Dynamo Process ◽  
Planetary Dynamos

AbstractPossibilities and difficulties of applying the theory of magnetic field generation by convection flows in rotating spherical fluid shells to the Giant Planets are outlined. Recent progress in the understanding of the distribution of electrical conductivity in the Giant Planets suggests that the dynamo process occurs predominantly in regions of semiconductivity. In contrast to the geodynamo the magnetic field generation in the Giant Planets is thus characterized by strong radial conductivity variations. The importance of the constraint on the Ohmic dissipation provided by the planetary luminosity is emphasized. Planetary dynamos are likely to be of an oscillatory type, although these oscillations may not be evident from the exterior of the planets.

scholarly journals DEPENDENCE OF THE MAGNETIC FIELD GENERATION MODELS OF IN MODEL OF A αΩ-DYNAMO ON THE INTENSITY OF A POWER TYPE α GENERATOR

2019 ◽  
pp. 58-66
Author(s):  
А.Н. Годомская ◽  
О.В. Шереметьева
Keyword(s):  
Magnetic Field ◽  
Comparative Analysis ◽  
Velocity Field ◽  
Dynamic Model ◽  
Radial Component ◽  
Magnetic Field Generation ◽  
Power Type ◽  
Exponential Kernel ◽  
Field Generation ◽  
The Magnetic Field

В динамической модели -динамо с переменной интенсивностью -генератора моделируются инверсии магнитного поля. Изменение интенсивности -генератора как следствие синхронизации высших мод поля скоростей и магнитного поля регулируется функцией Z(t) со степенным ядром. Получены режимы динамо для двух видов радиальной составляющей в скалярной параметризации -эффекта. Проведён анализ результатов в зависимости от изменения показателя степени ядра функции Z(t), а также сравнительный анализ с результатами исследования 10, где использовано показательное ядро функциии Z(t). In the dynamic model -dimensions are simulated reversions of the magnetic field with a varying intensity of the -generator. The change of the -generator intensity as a result of synchronization of higher modes of the velocity field and the magnetic field is regulated by a function Z(t) with a power kernel. Dynamo modes are obtained for two types of radial component in the scalar parameterization of the -effect. The results were analyzed depending on the change in the exponent of the kernel of the function Z(t), also a comparative analysis with the results of the study 10, where the exponential kernel of the function Z(t) was used.

scholarly journals Stability of H3O at extreme conditions and implications for the magnetic fields of Uranus and Neptune

2020 ◽  
Vol 117 (11) ◽  
pp. 5638-5643 ◽  
Author(s):  
Peihao Huang ◽  
Hanyu Liu ◽  
Jian Lv ◽  
Quan Li ◽  
Chunhong Long ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Thin Shell ◽  
Underlying Mechanism ◽  
Giant Planets ◽  
Dynamo Model ◽  
Extreme Conditions ◽  
Material Basis ◽  
The Magnetic Field ◽  
Planetary Dynamos

The anomalous nondipolar and nonaxisymmetric magnetic fields of Uranus and Neptune have long challenged conventional views of planetary dynamos. A thin-shell dynamo conjecture captures the observed phenomena but leaves unexplained the fundamental material basis and underlying mechanism. Here we report extensive quantum-mechanical calculations of polymorphism in the hydrogen–oxygen system at the pressures and temperatures of the deep interiors of these ice giant planets (to >600 GPa and 7,000 K). The results reveal the surprising stability of solid and fluid trihydrogen oxide (H3O) at these extreme conditions. Fluid H3O is metallic and calculated to be stable near the cores of Uranus and Neptune. As a convecting fluid, the material could give rise to the magnetic field consistent with the thin-shell dynamo model proposed for these planets. H3O could also be a major component in both solid and superionic forms in other (e.g., nonconvecting) layers. The results thus provide a materials basis for understanding the enigmatic magnetic-field anomalies and other aspects of the interiors of Uranus and Neptune. These findings have direct implications for the internal structure, composition, and dynamos of related exoplanets.

Simulation studies of the magnetic field generation in cosmological plasmas

2004 ◽  
Vol 330 (5) ◽  
pp. 384-389 ◽  
Author(s):  
Jun-Ichi Sakai ◽  
Reinhard Schlickeiser ◽  
P.K. Shukla
Keyword(s):  
Magnetic Field ◽  
Simulation Studies ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
The Magnetic Field

scholarly journals Generation of strong magnetic fields with a laser-driven coil

2018 ◽  
Vol 6 ◽  
Author(s):  
Zhe Zhang ◽  
Baojun Zhu ◽  
Yutong Li ◽  
Weiman Jiang ◽  
Dawei Yuan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Experimental Studies ◽  
Diagnostic Techniques ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Research Fields ◽  
Laser Facility ◽  
Spatio Temporal ◽  
The Magnetic Field

As a promising new way to generate a controllable strong magnetic field, laser-driven magnetic coils have attracted interest in many research fields. In 2013, a kilotesla level magnetic field was achieved at the Gekko XII laser facility with a capacitor–coil target. A similar approach has been adopted in a number of laboratories, with a variety of targets of different shapes. The peak strength of the magnetic field varies from a few tesla to kilotesla, with different spatio-temporal ranges. The differences are determined by the target geometry and the parameters of the incident laser. Here we present a review of the results of recent experimental studies of laser-driven magnetic field generation, as well as a discussion of the diagnostic techniques required for such rapidly changing magnetic fields. As an extension of the magnetic field generation, some applications are discussed.

scholarly journals Modes of magnetic field generation in models of a αΩ-dynamo with a power type α-generator

2019 ◽  
Vol 127 ◽  
pp. 02016 ◽  
Author(s):  
Anna Godomskaya ◽  
Olga Sheremetyeva
Keyword(s):  
Magnetic Field ◽  
Comparative Analysis ◽  
Velocity Field ◽  
Dynamic Model ◽  
Radial Component ◽  
Magnetic Field Generation ◽  
Power Type ◽  
Exponential Kernel ◽  
Field Generation ◽  
The Magnetic Field

In the dynamic model αΩ-dimensions are simulated reversions of the magnetic field with a varying intensity of the α-generator. The change of the α-generator intensity as a result of synchronization of higher modes of the velocity field and the magnetic field is regulated by a function Z(t) with a power kernel. Dynamo modes are obtained for two types of radial component in the scalar parameterization of the α-effect. The results were analyzed depending on the change in the exponent of the kernel of the function Z(t) and the type of the power kernel, also a comparative analysis with the results of the study [9], where the exponential kernel of the function Z(t) was used.

scholarly journals HIGH RESOLUTION SPECTROPOLARIMETRY OF THE SOLAR TWINS

2012 ◽  
Vol 18 ◽  
pp. 63-66
Author(s):  
THARCISYO DUARTE ◽  
J. D. DO NASCIMENTO
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Large Scale ◽  
Solar Magnetic Field ◽  
Physical Parameters ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Large Scale Magnetic Field ◽  
New Generation ◽  
Dynamo Process

The study of solar twins offers a unique opportunity to investigating the solar magnetic field over longer timescales. Supported by the new generation of stellar spectropolarimeters (ESPaDOnS@CFHT, NARVAL@TBL), we are able to measure the large-scale magnetic field solar twins. Studying the behavior of solar magnetic field, we are able to learn about the mechanisms of magnetic field generation in the dynamo process. Besides convection, various physical parameters affect the dynamo operation, in particular the rotation and mass. We collected signature of the stellar large-scale magnetic field for solar twins and we present here a analysis of seven candidates.

scholarly journals Generation of the Seed Magnetic Field

1993 ◽  
Vol 157 ◽  
pp. 421-425
Author(s):  
A. Lazarian
Keyword(s):  
Magnetic Field ◽  
Molecular Clouds ◽  
The Other ◽  
Small Scale ◽  
Magnetic Field Generation ◽  
Average Value ◽  
Field Generation ◽  
Seed Field ◽  
Direct Generation ◽  
The Magnetic Field

Two mechanisms of the galactic seed field generation are discussed. One of the mechanisms implies a direct generation of the seed magnetic field through a battery process (Lazarian 1992a). The other accounts for the possibility of the preliminary amplification of the magnetic field on a scale of molecular clouds (Lazarian 1992b). This means that the galactic dynamo can feed on the non-zero average value of the magnetic field amplified by such a small-scale dynamo. It is shown that both mechanisms can generate an adequate seed field. These two scenarios of the seed magnetic field generation can be distinguished by an analysis of the present day galactic magnetic structure.

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