Halbach-Array

A Halbach array is a special configuration of permanent magnets. Such a configuration enables the magnetic flux on one side of the configuration cancels almost, but more on the other side. Named such an arrangement by Klaus Halbach, then a scientist at the Lawrence Berkeley National Laboratory. Halbach introduced in 1980 as first a member ( a 16 -piece quadrupole ) of this kind before. However, many professional authors write to the first publication of J. Mallinson, who has already described this effect in 1973 under the name "one- sided flux " (Eng. " one-sided river ").

Construction

A Halbach array is composed of segments of permanent magnets whose magnetization direction is tilted against one another by 90 ° in the direction of the longitudinal axis of the array. Characterized the field lines on the back side, is tilted in the direction of the director field closer together, which causes an increase in magnetic flux density. On the opposite side of the field lines are less closely than in the undisturbed magnets, therefore the field is attenuated already at a short distance, or disappears entirely, as north and south poles alternate in each case.

Application

The property that the magnetic flux nearly cancels on one side of the Halbach array, is interesting in various applications, such as in magnetic ( Inductrack ). Holding Magnets ( decomagnets the fridge, magnetic board ) are often called Halbach array manufactured since so achieves a significantly lower amount of magnetic material in the same holding power.

During the construction of generators and electric motors annular Halbach arrays are interesting. The Halbach first investigated annular quadrupoles are used in particle accelerators. A relatively new application is the use of annular dipoles for NMR experiments.