Standard Configuration

This extraction line configuration is used to perform most types of ⁴⁰Ar/³⁹Ar analysis or ⁴He extraction for (U-Th)/He analysis.  Sample gas is evolved via either the CO₂ laser fusion cell (43.8 cc) or diode laser incremental heating cell (45.3 cc).  Both laser cells have access to a roughing line to facilitate evacuation of the cell after sample changes.  The laser cells also connect to a common "sample" manifold (19.4 cc) that has a dedicated turbo pump to aid bakeout and maintain low blanks.  As sample gas is liberated during lasing, it is purified with a 50 l/s SAES getter positioned near the sample manifold and a 10 l/s SAES getter located near the mass spectrometer inlet (combined getter plus inlet section = 368 cc).  The sample gas is transfered by expansion into the mass spectrometer (1887 cc).  If the procedure involves a single expansion, 81.4% of the sample gas reaches the mass spectrometer.  When a double expansion is used (i.e., sample gas within the sample manifold is isolated and pumped away prior to expansion into the mass spectrometer), 71.3% of the sample gas is analyzed.