Concentrating field lines of primary magnetic field in non-ferromagnetic material or in vacuum to form secondary magnetic field of increased flux density and with helical field lines

摘要

A ferromagnetic, wire-shaped material is formed into a helix which is open at one or both ends and comprises non-touching spiral windings. The helix is introduced into the primary magnetic field. The helix may be cylindrical or conical, or comprise a cylindrical and a conical portion. Several spirals of different diameters may be arranged coaxially, one inside the other.