核からのマグネシウム降水で地球のダイナモを動かす
Joseph G O'Rourke1, David J Stevenson1
1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA.
Nature
|January 22, 2016
まとめ
地球の磁場であるジオダイナモは 何十億年も活動しています 新しい研究では 核からのマグネシウムの降水が 単に冷却ではなく この古代の磁場を動かすことを示しています
科学分野:
- 地理学
- 惑星科学
- 地球科学
背景:
- 地球の磁場は 液体外核のコンベクションから発生します
- 古代磁気観測データによると 地磁石は少なくとも 34億年 活動しています
- 標準モデルは,組成的コンベクション,熱コンベクション,または放射性加熱を動力源として提案しています.
研究 の 目的:
- 地球のジオダイナモの代替エネルギー源を調査する
- 鉄の熱伝導性に関する新しい発見と調和させるため
- ゆっくり冷却されたり 放射線による加熱が最小限であっても ジオダイナモが存続する理由を説明するためです
主な方法:
- 最初の原理の計算と ダイヤモンド・アンビル・セル実験を用いて
- 鉄の熱伝導性が 核の動力学に及ぼす影響を分析する.
- マグネシウム含有鉱物降雨の浮力駆動動力源としての役割をモデル化.
主要な成果:
- 鉄の熱伝導性が高くなると 内部核が若いことが示され 既存のジオダイナモモデルに 異議を唱えます
- 核からのマグネシウムの降水は,内核の成長よりも効率的な浮力源を提供します.
- このプロセスは地球の歴史を通して持続的な地力発電を可能にします.
結論:
- マグネシウムの降水は 地質学的時間尺度で地球の地力学を動かす 有効なメカニズムを提供します
- この発見は少なくとも34億年前から現在まで ジオダイナモの継続的な動作を 裏付けています
- 鉄の最新高圧実験データによる不一致を解決した.
関連する概念動画
Faraday Disk Dynamo
4.1K
A Faraday disk dynamo is a DC generator, producing an emf that is constant in time. It consists of a conducting disk that rotates with a constant angular velocity in the magnetic field, perpendicular to the disk's plane. The rotation of the disk causes a change in magnetic flux, which induces an emf, causing opposite charges to develop on the rim and in the center of the disk. The polarity of the induced emf can be determined by the direction of the magnetic field and the direction of the...
4.1K
Magnetism
9.8K
Magnets are commonly found in everyday objects, such as toys, hangers, elevators, doorbells, and computer devices. Experimentation on these magnets shows that all magnets have two poles: one is labeled north (N) and the other south (S). Magnetic poles repel if they are alike and attract if unlike. Moreover, both poles of a magnet attract unmagnetized pieces of iron.
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
9.8K
Potential Due to a Magnetized Object
857
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
The vector...
857
Magnetic Fields
7.8K
A moving charge or a current creates a magnetic field in the surrounding space, in addition to its electric field. The magnetic field exerts a force on any other moving charge or current that is present in the field. Like an electric field, the magnetic field is also a vector field. At any position, the direction of the magnetic field is defined as the direction in which the north pole of a compass needle points.
A magnetic field is defined by the force that a charged particle experiences...
A magnetic field is defined by the force that a charged particle experiences...
7.8K
Magnetostatic Boundary Conditions
1.8K
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular component of a magnetic field is continuous across the interface of two magnetic mediums. In contrast, its parallel component, perpendicular to the current, is discontinuous by the amount equal to the product of the vacuum permeability and the surface current. Like the scalar potential in electrostatics, the vector potential is also continuous...
1.8K
Faraday's Law
6.4K
Faraday's law state that the induced emf is the negative change in the magnetic flux per unit of time. Any change in the magnetic field or change in the orientation of the area of the coil with respect to the magnetic field induces a voltage (emf). The magnetic flux measures the number of magnetic field lines through a given surface area. Magnetic flux is estimated from the integral of the dot product of the magnetic field vector and the area vector. The negative sign describes the...
6.4K


