Patent ID: 6157030
Filing Date: 2000-12-05
Classification: H01J

Abstract:
An ion trap mass spectrometer comprising an ion source for generating ions of sample molecules under an atmospheric pressure; a vacuum region which is evacuated to make a sufficient vacuum; a differential pumping region disposed in the middle of a path of the ions for sampling the ions generated by the ion source into the vacuum region; a focusing lens set inside the vacuum region for focusing the ions sampled into the vacuum region through the differential pumping region; a mass analysis region having a pair of endcap electrodes opposite to each other inside the vacuum region and a ring electrode arranged between the endcap electrodes, the mass analysis region being for mass-analyzing the ions focused by the focusing lens; and an ion detector for detecting the mass-analyzed ions, wherein a conductive mesh electrode is fitted to an end face at the side opposite to the ring electrode of an aperture made in the the endcap electrode arranged at the side of the focusing lens.