Wiktionary
reflectron
n. (context physics chemistry English) A time-of-flight mass spectrometry that uses a static electric field to reverse the direction of travel of the ions entering it.
Wikipedia
Reflectron
A reflectron (mass reflectron) is a type of time-of-flight mass spectrometer (TOF MS) that comprises a pulsed ion source, field-free region, ion mirror, and ion detector and uses a static or time dependent electric field in the ion mirror to reverse the direction of travel of the ions entering it. Using the reflectron, one can substantially diminish a spread of flight times of the ions with the same mass-to-charge ratio (m/z) caused by spread in kinetic energy of these ions measured at the exit from the ion source.