flux generated by the magnets which is an extremely high number and therefore a very high degree of waste in the overall system in order to reduce the wasted magnetic flux it is necessary to saturate the steel through which the magnetic flux passes or whichever material the sleeve is made of so that the magnetic flux density in the working gap for example the gap between the sleeve and the shaft if this is the dynamic gap is as high as possible the magnetic flux u03c6 required to saturate steel is defined by the equation where b s is the magnetic flux density necessary to saturate the steel the magnetic flux density necessary to saturate the steel s p is the area of the cross section of a single magnetic pole i e the sleeve between the bottom of the channel and the outer diameter of the sleeve b is the thickness of the sleeve between the bottom of the channel and the outer diameter and r p is the outer diameter of the sleeve on the other hand the same magnetic flux can be derived from the equation where b o is the magnetic flux density in a neutral cross section of the magnets s m is the pole area of the magnets h is the depth of the channel required for the additional magnets and r s is the radius of the shaft these equations can be rewritten to determine the depth of the channel for the additional magnets as follows typical values of the magnetic flux densities include b s 2 2 tesla b o 0.