Pulsed magnetic lenses for producing intense and bright cold atom beams

Abstract

We report on the experimental study of cold atom bunch imaging by means of magnetic forces. A cesium atom cloud is released at low temperature from a standard cold atom source with a repetition period of 1 s. This cloud has been imaged in one-, two- and three-dimensions at a distance of about 1 m by means of pulsed magnetic lenses made of simple coils. Strong space and velocity compressions have been achieved providing bright and intense cold polarized atom beams. Transverse temperatures down to 350 nK have been achieved by means of 3D-collimation. The 3D-imaging procedure yields a pulsed beam of 4-ms duration with a flux density up to 4.5×10 15 atoms/ s m 2 ; this figure represents a 20-fold increase in comparison with the free expanding cloud case. The duty cycle being 0.4% the mean temporal flux density is then 1.8×10 13 atoms/ s m 2 . 3D-collimation allows for the production of a pulsed beam of 4-ms duration and with a brightness up to 5×10 15 atoms/s sr. This represents a 12-fold increase in comparison with the free expansion case while the mean temporal brightness is 2.0×10 13 atoms/s sr.