A storage ring for neutral molecules

Time-varying inhomogeneous electric fields can be used to manipulate the motion of neutral molecules in phase-space, i.e., position-momentum space, via their electric dipole moment. A theoretical background is given on the motion of the molecules in phase-space. As the forces exerted on the molecules by the electric fields are conservative, Liouville's theorem dictates that the phase-space density remains constant. Starting from a pulsed supersonic expansion a package of neutral molecules can be decelerated, focused, cooled and confined using appropriately designed (time-varying) electric fields. In this way, deuterated ammonia molecules (ND_3) have been stored in a storage ring at very low translational temperatures and have been detected after more than 50 round trips. Temperatures on the order of 300 microKelvin have been obtained. A first study has been performed to investigate the dynamics of the molecules while they are stored in the ring. By splitting the ring in sections and inserting so-called bunchers it should be possible to detect the molecules after many more round trips. Numerical calculations are presented showing that such a sectional ring is experimentally feasibl