|
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.〔Garrett, Milan Wayne, Journal of Applied Physics, 38(6), pp2563-2586〕 According to Maxwell's original 1873 design:〔 Page 319.〕 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.〔R. Pascone, Manhattan College, T. Vullo and P.T. Cahill (1993) (Theoretical and experimental analysis of magnetic field gradients for MRI ) from IEEE Explore〕 If the current in one of the coils is reversed, a uniform-gradient magnetic field is produced near the centre of the two coils. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Maxwell coil」の詳細全文を読む スポンサード リンク
|