free electron laser

https://doi.org/10.1351/goldbook.F02514
Source of
coherent radiation
in which the
active medium
is an electron beam moving at speeds close to the speed of light in the spatially periodic magnetic field produced by an array of magnets (the wiggler). The emitted
wavelength
, λL, is approximately given by λω4 E2 with λω being the wiggler period and E the electron's energy in MeV.
See:
laser
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2244 [Terms] [Paper]