Patent ID: 9048081
Filing Date: 2015-06-02
Classification: H01J

Abstract:
1. A mass spectrometer comprising: a Time of Flight mass analyser comprising an acceleration electrode, a time of flight region and an ion detector; and a control system arranged and adapted to apply a first extraction pulse to said acceleration electrode in order to accelerate a first group of ions into said time of flight region at a first time T wherein said control system is arranged and adapted to apply a second extraction pulse to said acceleration electrode at a subsequent second time T wherein said mass spectrometer further comprises an acceleration region adjacent said acceleration electrode; and wherein said mass spectrometer further comprises a restriction device arranged upstream of said acceleration region, wherein said restriction device is arranged and adapted to restrict the upper and lower mass to charge ratios and thus the mass to charge ratio range of ions which are present in said acceleration region when an extraction pulse is applied to said acceleration electrode so that the mass to charge ratio range of ions which are subsequently accelerated into said time of flight region is restricted, wherein the restricted mass to charge ratio range of ions entering said Time of Flight mass analyser and arriving at said acceleration region varies over a timescale and wherein the period between extraction pulses is set based upon a predicted variation in the mass to charge ratio range of ions arriving at said acceleration region over said timescale wherein the mass to charge ratio range is deterministically restricted by synchronizing the pulsing of the acceleration with a release of ions from a travelling wave device, wherein the travelling wave device comprises an ion guide comprising a plurality of electrodes wherein one or more transient DC voltages or one or more transient DC voltage waveforms are applied to the electrodes to partition a continuous stream of ions into a series of packets of ions.