linear electron accelerator

https://doi.org/10.1351/goldbook.L03549
An evacuated metal tube in which electrons pass through a series of small gaps (usually) in the form of cavity resonators in the high frequency range) so arranged and spaced that, at a specific excitation frequency, the stream of electrons on passing through successive gaps gains additional energy from the electric field in each gap.
Source:
PAC, 1982, 54, 1533. (Glossary of terms used in nuclear analytical chemistry (Provisional)) on page 1545 [Terms] [Paper]