Elemental and isotopic compositions of noble gases (He, Ne, Ar, Kr and Xe) trapped in mantle-derived samples have provided unique and important constraints relating to the evolution of the Earth-atmosphere system. The amounts of noble gases in general mantle-derived rocks are very low and are sometimes 107-8 atoms in one gram of samples, thus we need a mass spectrometer with very good sensitivity which is proportional to the partial pressure of noble gases near the ionization source. In order to increase the sensitivity of noble gases for mass spectroscopic analysis, we have used the commercially available turbo molecular pump as a gas compressor.
During the analysis, the compressed sample gases are designed to directly recycled near the ionization source. Our preliminary results indicate that the apparent sensitivity of neon and xenon can be increased by at least 100. Apart from some problems regarding the impurity released from the compressor itself during the run, there is a possibility in this new system for enabling the analysis on samples with much smaller size (single grain or spot analyses) after adding some modifications to reduce the amounts of dirty gasses released during the analyses.