Anomalous behaviour of an ammonia beam maser employing a ring focuser

Abstract

It is shown experimentally that an ammonia maser employing a ring-type focuser operated with electrode voltages of opposite sign, +V1 and -V2, relative to a grounded maser cavity shows a reduced amplitude of oscillation for a particular combination of the applied voltages determined by the distance between focuser and cavity. The results are contrasted with those of Koshurinov (1969) who obtained a similar local minimum when mod V1 mod approximately= mod V2 mod using a quadrupole focuser. The phenomenon is attributed to spatial reorientation of molecules in the weak electric fringe field between the maser cavity and focuser.