Question about magnetohydrodynamics (MHD) for electricity production

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Discussion Overview

The discussion revolves around the application of magnetohydrodynamics (MHD) for electricity production, specifically exploring the feasibility of generating electricity by moving magnetic fields rather than moving charges. The scope includes theoretical considerations of MHD principles and potential designs for generators.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes a design involving spinning ferrite magnets to create a magnetic field in which plasma could generate electricity, questioning its viability.
  • Another participant asks about the energy source for the proposed system.
  • Some participants express uncertainty about the concept, suggesting that the setup resembles a generator but questioning the effectiveness of a time-independent magnetic field in inducing an electric field.
  • A later reply clarifies that while moving particles in a magnetic field can generate electricity, the proposed design may not work as both the magnetic field and the charge are stationary relative to each other, leading to a lack of induced electric field.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of the proposed design, with some questioning the underlying principles of MHD in this context. The discussion remains unresolved regarding the effectiveness of the suggested approach.

Contextual Notes

Limitations include assumptions about the symmetry of the setup and the nature of the magnetic field. The discussion does not resolve the mathematical implications of the proposed design.

DavAeroEng
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TL;DR
Is this design theoretically possible for electric energy production? Could be realised to be used to produce electricity?
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According to the MHD theory, is case of energy production, a magnetic appplying a magnetic field to a moving charge perpendicular to the magnetic field, that could be plasma as well a solution full of ions, and placing two plates, electricity could be produced.
Now I have a question, let's say instead of moving the charges, the magnetic field is moved, in paricular in a circular motion with two ring

magnets
Screenshot 2023-12-26 082619.png
like in the image. Let's say they are ferrite magnets, so the intesity is kinda low respect to neudium magnets. These are made spin very fast, in the same direction. Now in theory by putting the a charge in between, and I though to fire, that is a plasma, and two plates.

Could this design produce a relevant amount of electricity? Could this work?
Screenshot 2023-12-26 082619.png
 
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What is your energy source?
 
I'm not sure if I understand the concept, but it looks like you want to reproduce a generator - extracting electricity from the motion of the magnet rings? You get a force from a time-dependent magnetic field inducing an electric field, but the field here is time-independent.
 
mfb said:
I'm not sure if I understand the concept, but it looks like you want to reproduce a generator - extracting electricity from the motion of the magnet rings? You get a force from a time-dependent magnetic field inducing an electric field, but the field here is time-independent.
Yes exactly, Normally in MHD generators the hot gas is shoot in between the fixed magnetic field, but what if the plasma, in this case fire from the combustion stays in that semi-ring, and the magnets over them spins, could this setup produce electricity? In other words could moving the magnetic field like this produce the necessary lorentz force to produce electricity?
 
There is nothing moving here (besides the field source). A moving particles in a magnetic field works: In the reference frame of the magnetic field you have the particle moving, in the reference frame of the particle the field transforms to have an electric field component. But here both reference frames are identical and you only have a non-moving charge in a magnetic field, assuming perfect symmetry in the setup.
 

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