| 摘要 |
A magnetic field generator having a conductor winding shaped to lie over the surface of a cylinder such that four pairs of straight conductor elements lie parallel to the axis of symmetry (Z axis) of the cylinder equally spaced around its periphery. These elements are joined by 90 degree arc conductor elements. The winding is such that in the straight elements of each pair, current flow is the same direction while in adjacent peripheral elements, current flow is in opposite directions so that the magnetic field due to the current flowing through the peripheral elements is zero on the Z-axis while the current flow through the straight elements forms a quadripole magnetic field about the Z-axis. Modifications of the structure can be made to provide for six-pole, 8-pole, 12-pole, etc., structures. In each case, a single conductor formed into an appropriate sequence of meanders can be used to produce the desired structure, thereby simplifying fabrication. Such structures have the advantage of reduced winding induction in relation to the magnetic field strength produced by the coil structure and are particularly suited for use in electron beam machines, for example, in the provision of an astigmatism correction coil.
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