Magnetism and Reentry: Could a Halbach Array Reduce Heat?

In summary, it's uncertain whether a Halbach array magnetically levitates a reentry vehicle away from the plasma (IOW, recalls the plasma away from the heat shield). It is possible, but it would likely result in the magnets heating up.
  • #1
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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  • #2
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.
 
  • #3
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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  • #4
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.
 
  • #5
Wouldn't your array attract the charged particles as often as repel them, with no net effect?
 
  • #6
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?
 

1. What is a Halbach Array and how does it work?

A Halbach Array is a special arrangement of permanent magnets that produces a strong magnetic field on one side while canceling out the field on the other. This is achieved by arranging the magnets in a specific pattern that creates a magnetic flux that is stronger on one side and weaker on the other. The resulting magnetic field can be used to control the trajectory of a spacecraft during reentry.

2. How can a Halbach Array reduce heat during reentry?

During reentry, a spacecraft experiences intense heat due to friction with the Earth's atmosphere. By using a Halbach Array, the spacecraft can be steered to a shallower angle of descent, which reduces the amount of time it spends in the atmosphere and therefore reduces the amount of heat generated. The magnetic field also creates a cushion of plasma around the spacecraft, which acts as a heat shield and further reduces the amount of heat transferred to the spacecraft.

3. Are there any limitations to using a Halbach Array for reentry?

While a Halbach Array can be effective in reducing heat during reentry, there are several limitations to its use. The strength of the magnetic field decreases with distance, so the array must be positioned close to the spacecraft. Additionally, the array must be oriented correctly in order to steer the spacecraft in the desired direction. Furthermore, the magnetic field may interfere with other systems on board the spacecraft.

4. Has a Halbach Array been used for reentry before?

Yes, a Halbach Array was used in the 1990s for the reentry of the German ROSAT satellite. The array was able to reduce the spacecraft's descent rate by 60%, resulting in a lower peak temperature during reentry. However, the spacecraft still experienced significant heating and ultimately burned up in the atmosphere.

5. What are the potential future applications of using a Halbach Array for reentry?

There are several potential future applications of using a Halbach Array for reentry. One possibility is for reusable spacecraft, where the reduced heat during reentry could prolong the lifespan of the spacecraft. Another potential application is for small satellites that do not have the capability for traditional reentry methods, such as heat shields. The use of a Halbach Array could enable these satellites to safely return to Earth. Additionally, further research and development could lead to improvements in the technology and its effectiveness for reducing heat during reentry.

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