Adjustable multi-tesla permanent magnet field sources

Permanent magnet flux sources of the enhanced magic ring/magic sphere types with an outer to inner radium ratio of six can be made to be mechanically field adjustable from 0.0+or-4.0 T in working gaps transverse to the applied field. In adjustable sources of similar size with gaps longitudinal to the field, the somewhat smaller field range of 3.0 to 3.4 T is attainable. The cylindrical sources pose no difficulties of access or adjustability. Ways of providing these for the spheres as well are discussed.<>