Patent ID: 8492711

Claim:
A multi-turn time-of-flight mass spectrometer for determining a mass-to-charge ratio of an ion from a time of flight of the ion by ejecting ions in a pulsed fashion from an ion source, introducing the ejected ions into a loop-orbit section to make the ions repeatedly fly along a substantially identical orbit a plurality of times, detecting each of the ions deviated from the loop-orbit section, and determining the time of flight of the detected ion, the mass spectrometer comprising: a) a deflecting electrode unit located on a path extending from a point at which the ions deviate from the loop-orbit section to a below-mentioned ion detector; b) a voltage generator for applying a temporally varying voltage to the deflecting electrode unit to create an electric field having an effect of shifting an ion in a direction orthogonal to an incident direction of the ions entering the deflecting electrode unit; c) an ion detector for providing at least positional information indicating an arrival position of the ion in the direction in which the ion is shifted by the electric field created by the deflecting electrode unit, and temporal information indicating an arrival time of the ion; and d) a data processor for deducing a number of turns made by an ion in the loop-orbit section, based on the positional information indicating the arrival position of the ion at the ion detector and the temporal information indicating the arrival time of the ion, and for calculating the mass-to-charge ratio of the ion by using information indicating the deduced number of turns.