Lecture

MHD Dynamo: Plasma Flow to Magnetic Fields

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Description

This lecture covers the basics of magnetohydrodynamics (MHD) dynamo, focusing on the process of magnetic field generation by the inductive action of a conductive fluid. Topics include the homopolar disk dynamo, dynamo theorems, solar surface and interior rotation, MHD induction equation, Reynolds number, and the Babcock-Leighton mechanism. The lecture also discusses the consequences of a high magnetic Reynolds number, the Q-effect, and the a-effect in the context of dynamo theory. It concludes with a discussion on the challenges of numerical simulations in understanding dynamo processes.

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Plasma Physics: Applications

This physics course, taught by world-renowned experts in the field, will provide you with an overview of applications in plasma physics. From the study of far distant astrophysical objects, over diverse applications in industry and medicine, to the ultimate goal of sustainable electricity generation from nuclear fusion. In the first part of this course, you will learn how nuclear fusion powers our Sun and the stars in the Universe. You will explore the cyclic variation of the Sun’s activity, how plasma flo

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Plasma physics: Space-plasma physics

Related concepts (32)

Magnetohydrodynamics

Magnetohydrodynamics (MHD; also called magneto-fluid dynamics or hydromagnetics) is a model of electrically conducting fluids that treats all interpenetrating particle species together as a single continuous medium. It is primarily concerned with the low-frequency, large-scale, magnetic behavior in plasmas and liquid metals and has applications in numerous fields including geophysics, astrophysics, and engineering. The word magnetohydrodynamics is derived from magneto- meaning magnetic field, hydro- meaning water, and dynamics meaning movement.

Magnetohydrodynamic generator

A magnetohydrodynamic generator (MHD generator) is a magnetohydrodynamic converter that transforms thermal energy and kinetic energy directly into electricity. An MHD generator, like a conventional generator, relies on moving a conductor through a magnetic field to generate electric current. The MHD generator uses hot conductive ionized gas (a plasma) as the moving conductor. The mechanical dynamo, in contrast, uses the motion of mechanical devices to accomplish this.

Magnetic reconnection

Magnetic reconnection is a physical process occurring in electrically conducting plasmas, in which the magnetic topology is rearranged and magnetic energy is converted to kinetic energy, thermal energy, and particle acceleration. Magnetic reconnection involves plasma flows at a substantial fraction of the Alfvén wave speed, which is the fundamental speed for mechanical information flow in a magnetized plasma. The concept of magnetic reconnection was developed in parallel by researchers working in solar physics and in the interaction between the solar wind and magnetized planets.

Induction equation

In magnetohydrodynamics, the induction equation is a partial differential equation that relates the magnetic field and velocity of an electrically conductive fluid such as a plasma. It can be derived from Maxwell's equations and Ohm's law, and plays a major role in plasma physics and astrophysics, especially in dynamo theory. Maxwell's equations describing the Faraday's and Ampere's laws read: and where: is the electric field. is the magnetic field. is the electric current density.

Dynamo theory

In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field. The dynamo theory describes the process through which a rotating, convecting, and electrically conducting fluid can maintain a magnetic field over astronomical time scales. A dynamo is thought to be the source of the Earth's magnetic field and the magnetic fields of Mercury and the Jovian planets.

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