Construction of a low velocity metastable helium atomic beam

Abstract

A bright metastable atom source at 80 K Rev. Sci. Instrum. 72, 2558 (2001); 10.1063/1.1372169 Continuous, dense, highly collimated sodium beam Rev. Sci. Instrum. 71, 3668 (2000)We have constructed an atomic beam of metastable helium atoms He͑2 3 S) with a mean velocity of 300 m/s ͑15 K͒ and a yield of 3ϫ10 12 atoms/s sr. The metastable atoms are produced in a dc discharge in a cryogenic environment cooled by liquid helium. Using a hexapole magnetic lens, we have increased further the beam intensity by focusing the metastable atoms. Initial studies show a factor of 2.5 increase in the beam flux but more is expected when the hexapole is constructed from permanent hexapole magnets. The He͑2 3 S) atoms are subsequently loaded into a magneto-optical trap.

Cold and trapped metastable noble gases

“…This is achieved by transverse collimation of the beam of metastable atoms using two-dimensional (2D) transverse radiative pressure forces (Aspect et al, 1990;Hoogerland et al, 1996b;Metcalf and van der Straten, 1999;Morita and Kumakura, 1991;Partlow et al, 2004;Rasel et al, 1999;Rooijakkers et al, 1996;Shimizu et al, 1987Shimizu et al, , 1990Vansteenkiste et al, 1991), focussing in a hexapole (Woestenenk et al, 2001) or 2D magneto-optical compression (Labeyrie et al, 1999;Schiffer et al, 1997;Scholz et al, 1994). For maximum efficiency, the collimation zone, which has a typical length of several to a few tens of cm, has to be implemented as close as possible to the source, typically directly after the skimmer.…”

“…4). The source is cooled by liquid nitrogen (Kawanaka et al, 1993) or in some cases even by liquid helium (Aspect et al, 1988;Carnal and Mlynek, 1991;Swansson et al, 2004;Woestenenk et al, 2001) for a reduction of the initial mean velocity of the resulting atomic beam.…”

“The Even-Lavie valve as a source for high intensity supersonic beam”

“…There were several attempts to combine a nozzle with electrical or laser discharge scheme to produce these species. In most cases the excitation process warms the supersonic jet, or contaminates it with sputtered electrode material [47][48][49][50][51][52]. We have developed a new type of electrode less Dielectric Barrier Discharge [53][54][55][56] source that does not heat the jet or contaminates it [57].…”

Low-pressure source of slow metastable rare gas atoms

“…8 These methods are somewhat cumbersome, however, and in addition do not work for the heavier RGs since these would simply condense at such low temperatures.…”