Review of Scientific Instruments
Construction of a low velocity metastable helium atomic beam
G.R. Woestenenk, Jan W. Thomsen, Milou van Rijnbach, P. van der Straten, Arend Niehaus
Abstract
We have constructed an atomic beam of metastable helium atoms He(2 3S) with a mean velocity of 300 m/s (15 K) and a yield of 3×1012 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 He(2 3S) atoms are subsequently loaded into a magneto-optical trap.