A sextupole magnet system for the production of intense polarized hydrogen atomic beams at low temperature

To take full advantage of a low velocity beam in the production of intense polarized hydrogen atomic beams a new sextupole magnet system has been developed and installed on the atomic beam apparatus of the ETH polarized ion source. Both practical considerations and theoretical investigations provided the criteria for the general design of the two-magnet system. The pole pieces are designed in a modular way, which allows to match the two-magnet system to various geometries of the apparatus and to different beam temperature. A new method was used which is based on the calculation of acceptance diagrams in order to investigate an optimal configuration of the whole system (diaphragms, magnets, drift spaces, ionizer). The efficiency of the beam transportation, defined as the ratio of the mean atomic density in the ionizer to the density at the skimmer location, is calculated to be one order of magnitude larger than in the previous source at room temperature.