Magnetohydrodynamic Turbulence and Dynamo — Lesson 4

This lesson covers the concept of Magnetohydrodynamic (MHD) turbulence and Dynamo, explaining how magnetic fields are generated without any external magnetic field. The lesson delves into the theory of Dynamo, which was proposed in 1990 for the sun and earth's magnetic field. It explains how the magnetic field is self-induced and how it can be generated by its own. The lesson also discusses the concept of energy transfers and how they play a crucial role in the growth of the magnetic field. For instance, the lesson uses the example of a simulation done in a lab, where a small seed magnetic field was kept with a lot of kinetic energy, and how the magnetic energy increased over time.

Video Highlights

00:20 - Explanation of Dynamo and its working
01:33 - Explanation of how magnetic field is induced
02:58 - Discussion on the theory of Dynamo
05:57 - Explanation of the growth of magnetic energy
09:42 - Discussion on the models of galactic Dynamo
11:32 - Discussion on the significant transfers for small Prandtl number Dynamos

Key Takeaways

- Dynamo theory explains the generation of magnetic fields without any external magnetic field.
- The magnetic field is self-induced and can be generated by its own.
- Energy transfers play a crucial role in the growth of the magnetic field.
- Simulations can be used to understand the growth of magnetic fields.
- The concept of energy transfers can be used to make models of galactic dynamo and estimate the time scale.