Current density inside superconductors

In summary, the problem is to compute the H and J vectors inside an infinite superconducting slab with a given constant magnetic field outside. Using Maxwell's equations in Gaussian units, we can derive an equation for the J vector and solve it by integrating with the known values of H vector and B vector. The result is the J vector inside the slab.
  • #1
rheajain
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Homework Statement



consider an infinite superconducting slab of thickness 2d (-d<=z<=d), outside of which there is a given constant magnetic field parallel to the suface. Hx =Hz=0 hy= H0 (some value for z<d and z>-d) , with E vector= D vector=0 everywhere. compute H vector < J vector inside the slab, assuming surface currents and charges absent.

Homework Equations


consider Maxwell's equations in Gaussian units:
divergence D vector= 4∏ρ
divergence of B vector = 0
curl of E vector= -(1/c) partial differential of B with respect to time.
curl of H vector= (1/c) partial differential of D with respect to time + (4∏/c)J vector
with D=E+4∏Pvector
B vector = H vector + 4∏M vector
now inside superconductor
current density obeys following equation:
c * curl(λJ)= -B , partial differential of (λJ) with respect to time= E
λ is a constant


The Attempt at a Solution



 
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  • #2
now as E vector and D vector are 0 so curl of E vector=0 and divergence of B vector=0. thus we get equation for J vector:curl(λJ)= -B as H vector is known outside the slab so we can calculate B vector also. we know that J vector is constant inside the slab, so we can integrate:lambda*integral(J)dxdy dz=-integral(B)dxdy dz on solving this equation we can get J vector inside the slab.
 

Related to Current density inside superconductors

1. What is current density inside superconductors?

Current density inside superconductors refers to the amount of electrical current that can flow through a unit area of the material. This value is typically very high in superconductors due to their ability to carry current without resistance.

2. How is current density affected by temperature in superconductors?

In superconductors, current density is inversely proportional to temperature. As the temperature of the material decreases, the current density increases, reaching its maximum value at the critical temperature where the material becomes a superconductor.

3. Can the current density inside a superconductor be exceeded?

No, the current density inside a superconductor cannot be exceeded. Superconductors have a critical current density, beyond which they will lose their superconducting properties and behave like a normal conductor.

4. How does the geometry of a superconductor affect its current density?

The geometry of a superconductor can greatly affect its current density. Thinner and longer superconductors have higher current densities, while thicker and shorter ones have lower current densities.

5. What are the applications of high current density in superconductors?

The high current density of superconductors makes them ideal for use in various applications such as MRI machines, particle accelerators, and power transmission lines. It also allows for more efficient use of electricity and can lead to cost savings in energy production.

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