radial electrostatic field analyser

in mass spectrometry
https://doi.org/10.1351/goldbook.R05034
An arrangement of two conducting sheets forming a capacitor and giving a radial electrostatic field which is used to deflect and focus ion beams of different energies. The capacitor may be cylindrical, spherical, or toroidal.
Source:
Orange Book, 2nd ed., p. 201 (https://media.iupac.org/publications/analytical_compendium/)