Improved helium exchange gas cryostat and sample tube designs for automated gas sampling and cryopumping

Abstract

In order to eliminate the use of liquid helium for the extraction of atmospheric gases from polar ice cores, two units of a redesigned top load helium exchange gas cryostat were built and tested. The cryostats feature the shortest and largest diameter sample wells built to date, a base temperature below 7 Kelvin, and a sample well without baffles. The cryostats allowed shortening the length and thus increasing the gas pressure inside our sample tubes by 58% and increasing the amount of sample ending up in the mass spectrometer by 4.4%. The cryostats can either be used as mobile stand-alone units for manual gas processing lines or integrated into a fully automated vacuum extraction and gas analysis line. For the latter application the cryostat was equipped with a custom-designed automated changeover system. © 2006 by the American Geophysical Union.