Abstract: A time-of-flight mass spectrometer capable of cutting out a major portion of carrier gas-derived ions ahead of the ion reservoir. The ion source is of the electron impact type and has source magnets for deflecting some of the produced ions away from the center axis of the ion reservoir. Electrostatic lenses for promoting the deflection of the ions caused by the source magnets and a differentially pumped slit for cutting off the deflected ions are mounted downstream of the ion source.

Abstract: A time-of-flight mass spectrometer capable of cutting out a major portion of carrier gas-derived ions ahead of the ion reservoir. The ion source is of the electron impact type and has source magnets for deflecting some of the produced ions away from the center axis of the ion reservoir. Electrostatic lenses for promoting the deflection of the ions caused by the source magnets and a differentially pumped slit for cutting off the deflected ions are mounted downstream of the ion source.

Abstract: There is disclosed a time-of-flight (TOF) mass spectrometer using microchannel plates (MCPs), that are prevented from saturating even if strong ion pulses hit the microchannel plates. Usually, the saturation would result in a dead time, removing parts of the produced mass spectrum and shortening the lifetimes of the microchannel plates. An intermediate ion detector is mounted at the spatial focusing point of a reflectron TOF-MS spectrometer portion to measure the current values of ion pulses arriving from an external ion source, as well as the elapsed times since start of travel of the ion pulses. Information obtained by the measurement is fed back to the final ion detector. Thus, the gain of the final ion detector is controlled before the ion pulses reach the final ion detector. This prevents saturation of the final ion detector. The invention can also be applied to a TOF mass spectrometer using pulsed ionization and to an electrostatic sector field TOF mass spectrometer.