在线词典

A free-electron laser (FEL), is a type of laser that shares the same optical properties as conventional lasers such as emitting a beam consisting of coherent electromagnetic radiation that can reach high power, but that uses some very different operating principles to form the beam. Unlike gas-, liquid-, or solid-state lasers such as diode lasers, in which electrons are excited in bound atomic or molecular states, free-electron lasers use a relativistic electron beam that moves freely through a magnetic structure, hence the term free electron as the lasing medium.