Abstract: A mass spectrometer is operated by generating a test packet of ions from a pulsed ion source. A population of ions derived from the test packet of ions is detected. A number of ionization events of the pulsed ion source is determined that will be required to provide an analysis packet of ions expected to have a desired population of ions. An analysis packet of ions is produced by accumulating ions for the determined number of ionization events.

Abstract: A time-of-flight mass spectrometer includes a sample holder for a sample and an ionizer for ionizing the sample to form ions. A first element is spaced downstream from the sample holder, a second element is spaced downstream from the first element, and a drift region is downstream of the second element. An electric field is established between the sample holder and the first element at a time subsequent to ionizing the sample in order to extract the ions. A time-dependent and mass-correlated electric field is established between at least one of: (a) the first element and the second element, and (b) the sample holder and the first element. In turn, a detector detects the ions.