Focusing Molecular Beams of NH3

Abstract

The problem of forming molecular beams for use in ammonia masers is examined. It is shown theoretically and experimentally that through the use of a new type of parabolic focuser with a ``point source'' effuser, the molecular flow may either be reduced by a factor of 8, for the same power output, or the power output may be increased by a factor of 2 for the same molecular flow. A theory of beam formation in a multitube effuser is described. This shows that the most intense molecular beam is formed by an effuser of small overall diameter. Design considerations are discussed for parabolic, upper-state focusers, and for coaxial, lower-state focusers. The operation of a system is described, using a lower-state focuser and an ionization detector, in which lower-state molecules produced by maser oscillation may be detected.