dynamic field(s) mass spectrometer

A mass spectrometer in which the separation of a selected ion beam depends essentially on the use of fields, or a field, varying with time. These fields are generally electric.
Orange Book, 2nd ed., p. 202 (https://media.iupac.org/publications/analytical_compendium/)
PAC, 1991, 63, 1541. 'Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)' on page 1545 (https://doi.org/10.1351/pac199163101541)