Calculating/estimating Eddy currents due to B-field

In summary, eddy currents are circulating currents induced in a conductor by a changing magnetic field, also known as the B-field. The strength and direction of the eddy currents are directly related to the strength and direction of the B-field. The magnitude and direction of eddy currents can be calculated using the equation E = -N dΦ/dt, where E is the emf induced by the B-field, N is the number of turns in the conductor, and dΦ/dt is the rate of change of magnetic flux. The strength of eddy currents is influenced by the strength and frequency of the B-field, the electrical conductivity and thickness of the conductor, and the shape and size of the conductor. The power losses due
  • #1
optophysicist
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Its been 15+ years since I have done any calcs like this and am very rusty, so even just a pointer in the right direction would be really appreciated...

I need to calculate/estimate the magnitude/value (IF any!) of eddy currents that would/could be generated in an ultra high speed rotating disc (>35,000 rpm) made of aluminium alloy or non-mag stainless steel, when placed/located such that it intercepts at/near the 'focus' of a electromagnetic solenoid lens (used to focus an electron beam).

Anyone?
 
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  • #2
If I'm not mistaken, Smithe's "Static and Dynamic Electricity" addresses that topic
 
  • #3


Calculating or estimating the eddy currents in this scenario would require understanding the principles of electromagnetism, specifically Faraday's law of induction. Eddy currents are induced in conductive materials when they are exposed to a changing magnetic field, such as the one generated by the solenoid lens. The magnitude of these currents depends on various factors such as the material properties, the strength and frequency of the magnetic field, and the geometry of the disc.

To start, you would need to determine the strength and frequency of the magnetic field generated by the solenoid lens. This can be done through measurements or calculations using the lens's specifications. Next, you would need to know the material properties of the disc, such as its electrical conductivity and magnetic permeability. From there, you can use Faraday's law to calculate the induced eddy currents.

Another approach would be to use simulation software, such as finite element analysis, to model the disc and the solenoid lens and calculate the eddy currents. This would provide a more accurate estimation, taking into account the specific geometry and material properties of the disc.

In either case, it is important to note that the eddy currents would also depend on the relative position and orientation of the disc with respect to the solenoid lens. Therefore, it would be helpful to have more specific information about the setup in order to make a more accurate calculation or estimation.

Overall, it would be best to consult a textbook or research paper on electromagnetism for a more detailed understanding of how to calculate or estimate eddy currents in this scenario. Additionally, seeking guidance from a colleague or mentor with expertise in this area would also be beneficial.
 

What are eddy currents and how are they related to B-field?

Eddy currents are circulating currents induced in a conductor when it is exposed to a changing magnetic field, also known as the B-field. The strength and direction of the eddy currents are directly related to the strength and direction of the B-field.

How do you calculate the magnitude and direction of eddy currents?

The magnitude and direction of eddy currents can be calculated using the equation E = -N dΦ/dt, where E is the emf (electromotive force) induced by the B-field, N is the number of turns in the conductor, and dΦ/dt is the rate of change of the magnetic flux through the area enclosed by the conductor.

What factors influence the strength of eddy currents?

The strength of eddy currents is influenced by the strength and frequency of the B-field, the electrical conductivity and thickness of the conductor, and the shape and size of the conductor.

How do you estimate the power losses due to eddy currents?

The power losses due to eddy currents can be estimated using the equation P = I^2R, where P is the power loss, I is the rms (root mean square) value of the eddy current, and R is the resistance of the conductor. The resistance can be calculated using the material's resistivity and the dimensions of the conductor.

What are some applications of eddy currents?

Eddy currents have many applications, such as in electric motors, generators, and transformers where they can cause energy losses and heating. They are also used in non-destructive testing to detect cracks or defects in metal objects, and in induction heating for melting or welding metals.

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