A surface polaritons
Cherenkov radiation source (SPCRS) belongs to an electromagnetic wave
radiation source technology field. The
radiation source comprises: an
electron gun, a medium torus (or a medium cylinder) and a
metal film layer deposited on an internal surface of the medium torus (or deposited on an external surface of the medium cylinder). An
electron beam emitted from the
electron gun is swept past from a
metal film layer surface so as to excite a surface polaritons wave on the
metal film layer surface. The surface polaritons wave penetrates the metal film layer and arrives at a medium material layer. When a ratio beta of a
moving speed of the electron beam emitted by the
electron gun to a light velocity in vacuum and a
refractive index n of the medium material layer satisfy a Cerenkov
radiation condition which is n beta>1, the surface polaritons wave is converted into the Cerenkov radiation in the medium material layer. A
radiation frequency is determined by the frequency of the surface polaritons wave excited by the electron beam. Through changing moved
electron energy, the frequency of the excited surface polaritons wave can be changed so as to tune the frequency of the
electromagnetic radiation source. The radiation source of the invention has a small size, a
narrow bandwidth and a
low voltage, and is tunable and easy to be integrated.