Multipole coils

Abstract

Multipole coils (1, 2, 3, 4, 5, 6) comprise at least two coils (1, 2) which are disposed to concentrically enclose an imaginary axis (10). Multipole coils (1, 2, 3, 4, 5, 6) of this type are designed in such a fashion that effective fields can be generated in the area of an imaginary axis (10) when little installation space is available, and the multipole coils can be reproducibly manufactured with high precision. This is achieved in that, for each coil (1, 2, 3, 4, 5, 6), at least one winding (7) is disposed on a flexible printed circuit board (8) through disposed strip conductors (9), and the printed circuit board (8) is rolled in at least one printed circuit board layer (11, 12, 13, 14).

Description

[0001]This application claims Paris Convention priority of DE 10 2007 045 874.8 filed Sep. 25, 2007 the complete disclosure of which is hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]The invention concerns multipole coils comprising at least two coils which are disposed to concentrically enclose an imaginary axis. Multipole coils of this type are used to generate magnetic fields which are disposed concentrically about an imaginary axis. A dipole, a quadrupole, a hexapole, an octupole etc. can e.g. be formed in this fashion.[0003]The main field of application is the influence of particle beams, i.e. ion or electron beams in particle optics. Since 1947, when O. Scherzer showed that the optical path of electron lenses can be corrected by non-rotationally symmetrical lenses (O. Scherzer: “Sphärische und chromatische Korrektur von Elektronen-Linsen” (spherical and chromatic correction of electron lenses), OPTIK, DE, JENA, 1947, pages 114-132, XP002090897, ISSN: 0863-02...

AI Technical Summary

Benefits of technology

[0012]The reduction in installation space is also advantageous in that the coils are positioned closer to the location of use of the generated fields, and therefore produce fields of higher precision. The number of windings that are required for generating the field is also smaller compared to prior art, such that considerably stronger fields can be generated at the location of use with the same current strength. The field that can be generated using the same current strength is approximately four times stronger. Alternatively, it is also possible to use a correspondingly smaller current strength to obtain the same field.

[0038]The invention is advantageous compared to prior art due to the minimum space requirements. The accommodation of conventional, wound coils would require considerably larger recesses, e.g. in a magnetic lens. This would change the geometry of such a lens and have a negative effect on the generated magnetic field. The small installation space of the inventive multipole coils completely or largely eliminates such geometrical changes. A correction element can thereby be inserted with minimum disturbance of the lens field.

Problems solved by technology

Multipoles of this type require a large amount of space, comprise fields which are ineffective with respect to the area of the axis due to the large distance from the axis, and cannot be manufactured in an exactly reproducible fashion, since deviations cannot be prevented during winding of the wires both manually as well as mechanically.

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