A solution of the present invention is to divide {HEAD ~ each back iron} into {TAIL ~ segments} such that there is a physical air gap between the back iron segments of two adjacent magnet clusters 
into
A solution of the present invention is to divide { HEAD ~ each back iron } into { TAIL ~ segments } such that there is a physical air gap between the back iron segments of two adjacent magnet clusters
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH