Page "Electron" Paragraph 18

In the free electron laser ( FEL ), a relativistic electron beam is passed through a pair of undulators containing arrays of dipole magnets, whose fields are oriented in alternating directions.

The electrons emit synchrotron radiation, which, in turn, coherently interacts with the same electrons.

This leads to the strong amplification of the radiation field at the resonance frequency.

FEL can emit a coherent high-brilliance electromagnetic radiation with a wide range of frequencies, from microwaves to soft X-rays.

These devices can be used in the future for manufacturing, communication and various medical applications, such as soft tissue surgery.