Ion filling control in ion trap mass spectrometers

摘要

The invention relates to the control of the filling process of an ion trap with ions in order to avoid the deteriorating effect of too many stored ions on the quality of the spectrum during a mass scan. In the prior art, the "number of ions" inside the ion trap were used to contol filling. However, controlling the number of ions does not provide optimum trap filling for different ion compositions. The invention overcomes the problem by controlling a mass-dependent physical parameter and applying an cluster-dependent target value. This method takes into account the mass-dependency of optimum ion filling as well as the effect of non-uniform distribution of ions of different mass-to-charge ratios over the mass spectrum.