Field structure for tubular linear permanent magnet machines

A novel structure for the field component of a class of linear tubular permanent magnet machines is presented. The new structure offers a reduction in the required steel for a given design, and offers the possibility to achieve a more efficient cooling of the field component, and therefore magnets. Finite element simulations of example designs are presented, which show that the form and magnitude of the flux linkage in the coils can be maintained with the reduced mass structure.