Measurements of the atomic beam formed by a focusing capillary array

The properties of a helium atomic beam formed by a fused glass focusing array of about 10 7 capillaries each 5 mu m in diameter and 2.5 mm long, the axes of which are directed to a point 50 mm from the array have been investigated. The axial atom density and the total throughput are consistent with Zugenmaier's theory for a single capillary. The beam halfwidth is anomalously six times wider than expected theoretically, but it is shown that this is not primarily due to a constructional error in the array. An axial helium density of 10 14 atoms/cm 3 at a beam width of 5 mm was obtained at an input pressure of 2 Torr, with a total helium throughput of 1.5*10 19 atoms/s.