Abstract: An improvement in an atomic or molecular magnetic quantum state selector wherein the bore and gap spacing may be adjusted or calibrated precisely after assembly by providing adjustable segments in the supporting structure surrounding the pole tips. The adjustable bore and gaps make it feasible to construct small size state selectors with precision bore and gap dimensions which have heretofore been difficult or impossible to realize due to the unrealistically small dimensional tolerances which would be required in previous conceptions of these devices.

Abstract: An improvement in an atomic or molecular frequency standard, more particularly, the atomic hydrogen maser, by the use of electrode structures circumferentially placed around the exterior of the atomic or molecular storage vessel and in a surface of revolution about the initial atomic hydrogen beam path. These electrodes allow maser action in maser devices of physical dimensions much smaller than those formerly possible.