An instrument in which an ion beam with a given value of mass/charge is brought to a focus although the initial directions of the ions diverge.
Orange Book, 2nd ed., p. 201 [Terms
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 1546 [Terms