Magnetism and Reentry: Could a Halbach Array Reduce Heat?

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Discussion Overview

The discussion revolves around the potential application of a Halbach array of magnets in reducing heat transfer during the reentry of a vehicle. Participants explore the theoretical implications of using such an array to manipulate the plasma generated during reentry, considering both the mechanics of magnetic levitation and the thermal effects on the vehicle's heat shield.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes that a Halbach array could magnetically levitate a reentry vehicle away from the plasma, potentially reducing heat transfer to the heat shield.
  • Another participant questions the placement of the Halbach array, suggesting it might need to be above the heat shield to avoid melting, and expresses uncertainty about the array's operation.
  • A participant mentions that if the magnets were electromagnets, they would heat up due to electrical resistance, but not to the temperature of the plasma sheath.
  • One participant humorously compares the concept of using a magnetic field to "surfing a tsunami," indicating skepticism about the feasibility of the idea.
  • Another participant raises a concern that the Halbach array might attract charged particles as often as it repels them, questioning the net effect on the plasma.
  • A later reply clarifies that a Halbach array repels neutral rails in maglev systems, but notes that plasma is charged, suggesting a different interaction.
  • There is a suggestion that using permanent magnets with a specific orientation might be more effective than a Halbach array.

Areas of Agreement / Disagreement

Participants express a range of views on the feasibility and effectiveness of using a Halbach array in this context, with no consensus reached on its potential benefits or drawbacks. The discussion remains unresolved, with multiple competing ideas presented.

Contextual Notes

Participants acknowledge limitations in their understanding of the Halbach array and its application, as well as the complexities involved in the interaction between magnetic fields and charged plasma.

LURCH
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I was just wondering;

What would happen if a Halbach array of magnets were placed just beneath the heat shield on a reentry vehicle? The plasma produced by reentry is, essentially, charged particles moving at high speed. Would a Halbach array magnetically levitate the reentry vehicle away the from the plasma (IOW, recall the plasma away from the heat shield) the way it does with an inductrack maglev?

If so, would the increase in distance result in less heat being transferred to the vehicle, or with the work being done on the magnets caused them to heat up?
 
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I can't believe that no-one has responded to this. It's a very interesting question. While I've never heard of a 'Halbach array', I'm going on the assumption that it's the layout used for a typical maglev system. I'll look that up later.
I would suspect to start with that such an array would have to be above the heat shield rather than below it, to prevent it from melting. (Or did you mean 'beneath' as being in a deeper layer?)
If they're electromagnets rather than the permanent variety, they'd definitely heat up due to electrical resistance, but not to the temperature of the plasma sheath. The components would melt before that happened.
This is way beyond me, though, so I hope that someone else chirps up. I'm most interested to see what the consensus is.
 
The http://www.answers.com/topic/halbach-array").

(I should have put those links in the OP.)

I've also tried discussing the potential for this type of maglev for roller coasters (although I guess we'd have to just call it a "coaster," without the "roller"). But it's very difficult to introduce such a new idea to anyone who might be able to do something about it.
 
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While I muchly appreciate the link that you provided, I must readily admit that it is far beyond my understanding.
That having been said, I've never shied away from offering an uninformed opinion. :biggrin:
Skipping off of the plasma sheath sounds good to me in principle, as long as that sheath doesn't just shred the artificial magnetic field. It sort of seems like trying to surf a tsunami.
 
Wouldn't your array attract the charged particles as often as repel them, with no net effect?
 
mLuby said:
Wouldn't your array attract the charged particles as often as repel them, with no net effect?
I don't think that it would. A Halbach Array repels ordinary rails in an inductrack maglev. Of course, in that case, the rails are neutral whereas plasma is charged.

Perhaps just a set of permanent magnets with the positive pol facing outward?
 

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