Ion Storage in Three-Dimensional, Rotationally Symmetric, Quadrupole Fields. II. A Sensitive Mass Spectrometer

Abstract

A mass spectrometer has been constructed in which ions are trapped in a three-dimensional, rotationally symmetric, quadrupole field. Ions of a specific charge to mass ratio are stored and then periodically drawn out of the trapping field into an electron multiplier. The ion trapping feature permits integration of the ion current over long periods of time. Electrodynamic ion trapping also enables a long effective path length to be attained in a small size device. Ions have been stored for several days using a low-resolution mode. Experimental data are presented concerning storage time, resolution, and sensitivity. Factors affecting the peak shape include storage time, resolution, and bias voltage between the end-caps. The theoretical basis for the trapping of charged particles in a three-dimensional, quadrupole field is discussed in a companion paper.