US Patent 7759655 Pulsed ion source for quadrupole mass spectrometer and method

A variable duty cycle ion source assembly is coupled to a continuous beam mass spectrometer. The duty cycle can be adjusted based on previous scan data or real time sampling of ion intensities during mass analysis. This provides the ability to dynamically control the total number of ions formed, mass analyzed and detected for each ion mass of interest. A reflection mechanism that provides a variable duty cycle, enables electrons to be reflected through an ion volume multiple times before atoms or molecules are ionized in the ion volume, thereby providing for dynamic control of the ion population.