Collimated dual species oven source and its characterisation via spatially resolved fluorescence spectroscopy

Abstract

We describe the design, construction and characterisation of a collimated, dual-species oven source for generating intense beams of lithium and caesium in UHV environments. Our design produces full beam overlap for the two species. Using an aligned microtube array the FWHM of the output beam is restricted to ∼ 75 milliradians, with an estimated axial brightness of 3.6×10 14 atoms s −1 sr −1 for Li and 7.4×10 15 atoms s −1 sr −1 for Cs. We measure the properties of the output beam using a spatially-resolved fluorescence technique, which allows for the extraction of additional information not accessible without spatial resolution.

Comparative analysis of recirculating and collimating cesium ovens

“…For instance, in a dual Li/Cs beam, the Li behavior was the brightwall one where the Cs flux was found to be a factor 130 times smaller than expected in Ref. 35 [an alternative explanation for this discrepancy (involving worse light-gathering because of Cs coating the windows) is given in the article, but we believe it is instead just another observation that indeed Cs ovens almost always exhibit dark-wall behavior]. It was also clearly observed that following the oven installation and pumping, it takes time (hours for an oven at >120 ○ C or days if lower temperature) to see any Cs flux out of the tube.…”

“…or physical variables (temperature, pressure, etc.). 34 However, discrepancies between the calculated flux and measured flux of cesium ovens, common in the literature, 35 indicate that other factors can be preponderant. Indeed, the usual flux calculations consider no chemical interaction between emitted atoms and the surface of the tube.…”