Helmholtz coil - QuickField simulation example
A Helmholtz coil is a device for producing a region of nearly uniform magnetic field. This construction is formed by the two identical circular coils, placed symmetrically along a common axis, and separated by the distance H equal to the coil radius R. Both coils carry the same electric current I. Area of the quasi uniform field is located inside the coils.
How to find magnetic field uniformity in Helmholtz coil systems?
Answer Typical applications Geometry
Given Task
Solution
The field at the center between Helmholtz coils is:
Results
Flux density distribution around the Helmholtz coils
* Reference: http://en.wikipedia.org/wiki/Helmholtz_coil
Engineering question
Set up an axisymmetric QuickField DC Magnetics problem for Helmholtz coils and evaluate magnetic field uniformity from computed field results.
Helmholtz coils, laboratory reference coils, sensor calibration coils
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Simulation problem
Problem Type
Axisymmetric problem of DC magnetics
H = R = 1 m,
Each coil consists of 1 loop with total electric current of I = 1 A. Media around the coils is air.
Calculate the flux density distribution within the Helmholtz coil. Find the area of uniform field. Compare with analytical approximation.
Model may be defined and solved as a DC Magnetic analysis problem.
The field within Helmholtz coils at the axis may be estimated as*:
B(x) = 2B1(x) = 2 · μnIR² / 2(R² + x²)3/2
B(x=R/2) = 2 · μnIR² / 2(R² + (R/2)²)3/2 = 0.83/2 · μnI/R.
Analytical solution for I=1 ampere, R=1 meter and n=1 gives B(x=0) = 8.98e-7 T.
QuickField calculates flux density value at the center between Helmholtz coils as B = 8.95e-7 T.
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