| 摘要 |
<p>An apparatus for analyzing trace elements in a gas sample includes a feedback system (46, 64, 68, 70) for accurately regulating and sensing the pressure supplied to an ion chamber (32). The feedback system is capable of compensating for a wide range of input gas pressures from a source (36). The ion chamber (32) is a closed ion source which is resistant to corrosion and aids in the reduction of noise. An ion detector (34) is calibrated for accurately scaling the measurements of trace elements. Two filaments (96, 98) mounted outiside the ion chamber (32) adjacent apertures (90) in the chamber wall are thereby shielded from the ions. A quadrupole analyser (23) receives the ions through an aperture (88) and is shielded by the ion chamber (32) from electrons from the filaments (96, 98). The feedback system controls the pressure in a regulator module (46), thereby determining the ion chamber pressure through the pressure drop through the exit aperture (56) of the regulator module (46).</p> |
