Is there energy associated with flux pinning?

In summary, Flux pinning or quantum locking is a phenomenon where a superconductor suspended above a magnetic field appears to defy gravity due to the absence of work being done or movement. The force keeping the superconductor from falling is an electromagnetic force between the superconductor and the magnet or any other material it is in contact with. The energy needed to hold the superconductor up is stored in the magnetic field configuration. With the development of room temperature superconductors, levitation and suspension would essentially be free due to the absence of energy needed for the process.
  • #1
JohanWunderbar
3
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This is probably a very naive question, but I am trying to wrap my head around the concept of flux pinning (quantum locking).

For all intents and purposes, it appears as if a superconductor suspended above a magnetic field is defying gravity. I understand that there is no work being done (as there is no movement) but if I was to extend my arm and hold up a 100g superconductor, I would have to expend energy to prevent gravity from pulling it down. If a 100g superconductor is suspended above a magnet, is there energy associated this is 'anti-gravity' effect?

Thanks,

J
 
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  • #2
JohanWunderbar said:
but if I was to extend my arm and hold up a 100g superconductor, I would have to expend energy to prevent gravity from pulling it down.
Yours muscles would have to, but you would not use energy for holding it up, you would use energy for internal friction in your muscles. This is a purely biological effect. Replace your muscles by a table and you don't need energy.

Human muscles consist of many parallel fibers that can contract. They can't do that long, however. If you keep holding your arm up, you constantly have fibers stopping contracting, while others start contracting to take over: your muscles is in constant action internally. That's where your power goes.
 
  • #3
Thanks for the answer. I guess I am still a bit confused. I agree that a table would not need any energy to hold the SC up, but there would be physical contact between the table and the SC. My muscles would have to expend energy to hold the SC above the table, or if I suspended the SC above the table from a string, I would think that some energy would be stored in the string in the form of tension. When a SC is hanging over a magnet, not in physical contact, what is the force keeping the SC from falling and hitting the surface? From your answer it appears as if the magnet and the superconductor are essentially in physical contact, but I am not clear on what is mediating this interaction between the two objects.

What if I apply extra force (push down on) or add extra weight to the superconductor? Where does that energy go? Is it dissipated as heat? Is the amount of mass able to be levitated proportional to the strength of the magnet?

As a side note, if it is true that there is no energy used, does this mean that if (when?) room temperature superconductors are manufactured, that levitation/suspension would essentially be free? Frictionless motion, for example a car with permanent magnets on the bottom could float along a superconducting road surface and no energy would be needed for the levitation/suspension?
 
  • #4
Forget the muscles. They don't help if your question is about physics. Use a table.
JohanWunderbar said:
but there would be physical contact between the table and the SC
What is physical contact? It is an electromagnetic force between superconductor (or any other material) and table. It is very similar to the force between superconductor and magnet, this one just has a larger range. The string is doing the same. It is all electromagnetic forces between and within materials.
JohanWunderbar said:
What if I apply extra force (push down on) or add extra weight to the superconductor? Where does that energy go?
The energy to move the superconductor against a force? It is stored in the magnetic field configuration.
JohanWunderbar said:
Is the amount of mass able to be levitated proportional to the strength of the magnet?
With limits, but for small masses it should be.
JohanWunderbar said:
As a side note, if it is true that there is no energy used, does this mean that if (when?) room temperature superconductors are manufactured, that levitation/suspension would essentially be free? Frictionless motion, for example a car with permanent magnets on the bottom could float along a superconducting road surface and no energy would be needed for the levitation/suspension?
Right. Even today, cooling is the only thing that needs power.
 
  • #5
Thanks for taking the time to answer my question. Very helpful!
 

1. What is flux pinning and how is it related to energy?

Flux pinning is a phenomenon in which magnetic flux lines become trapped in a superconductor, preventing them from moving. This is related to energy because the trapped flux lines create a barrier that requires energy to overcome, making it more difficult for the superconductor to transition to a resistive state.

2. How does flux pinning impact the performance of superconductors?

Flux pinning can greatly impact the performance of superconductors by increasing their critical current density and improving their ability to carry electrical current. This is because the trapped flux lines act as microscopic highways for current to flow through, allowing the superconductor to maintain its superconducting state at higher magnetic fields.

3. Is there a limit to the amount of energy associated with flux pinning?

Yes, there is a limit to the amount of energy associated with flux pinning. This limit is known as the maximum pinning energy and is determined by the material properties of the superconductor, such as its critical temperature and critical current density.

4. How do scientists study the energy associated with flux pinning?

Scientists study the energy associated with flux pinning by performing various experiments, such as measuring the critical current density of different superconductors at different magnetic fields. They also use theoretical models and simulations to better understand the underlying mechanisms of flux pinning and its effects on superconductors.

5. Can flux pinning be controlled or manipulated?

Yes, flux pinning can be controlled and manipulated in various ways. For example, scientists can introduce defects or impurities into the superconductor to enhance or inhibit flux pinning. They can also apply external magnetic fields or use different types of superconductors to alter the behavior of flux pinning and improve the performance of superconductors.

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