Maxwell coil
A Maxwell coil is a device for producing a large volume of almost constant (or constant-gradient) magnetic field. It is named in honour of the Scottish physicist James Clerk Maxwell.
A Maxwell coil is an improvement of a Helmholtz coil: in operation it provides an even more uniform magnetic field (than a Helmholtz coil), but at the expense of more material and complexity.
Description
A constant-field Maxwell coil set consists of three coils oriented on the surface of a virtual sphere.[1]
According to Maxwell's original 1873 design:[2]
each of the outer coils should be of radius 
, and distance 
from the plane of
the central coil of radius 
.
The number of ampere-turns of each of the smaller coils should equal exactly 
of the middle coil.
This arrangement removes variations in magnetic field, up to its 6th-order derivative with respect to position, near the centre of the virtual sphere.
A gradient-field Maxwell coil is essentially the same geometry of the 3-coil configuration above, with the central coil removed to leave only the smaller two coils.[3] If the current in one of the coils is reversed, a uniform-gradient magnetic field is produced near the centre of the two coils.
See also
References
- ↑ Garrett, Milan Wayne, Journal of Applied Physics, 38(6), pp2563-2586
- ↑ Lua error in package.lua at line 80: module 'strict' not found. Page 319.
- ↑ R. Pascone, Manhattan College, T. Vullo and P.T. Cahill (1993) Theoretical and experimental analysis of magnetic field gradients for MRI from IEEE Explore
