Abstract: A device (100) for generating a coherent Smith-Purcell radiation including an electrically conducting diffraction grating (102), laterally delimited by two electrically conducting external sidewalls (104); and a source (101) for generating an electron beam (103) and for emitting it so that it passes above the diffraction grating (102). The device (100) also includes one electrically conducting intermediate wall (105), parallel to the external sidewalls (104), located inside the diffraction grating (102) to form several similar elementary diffraction gratings (1061,1062). The source (101) emits an electron beam (103) with a speed and a current density adapted such that each elementary diffraction grating (1061,1062) emits a Smith-Purcell radiation on the fundamental mode. The elementary diffraction gratings (1061,1062) interact with each other to reduce the saturation time necessary for the Smith-Purcell radiation to be produced.

Abstract: The invention relates to a device (100) for generating a coherent Smith-Purcell radiation comprising: an electrically conducting diffraction grating (102), laterally delimited by two electrically conducting external sidewalls (104); and a source (101) for generating an electron beam (103) and for emitting it so that it passes above the diffraction grating (102). According to the invention, the device (100) also comprises one electrically conducting intermediate wall (105), parallel to the external sidewalls (104), located inside the diffraction grating (102) to form several similar elementary diffraction gratings (1061,1062). The source (101) emits an electron beam (103) with a speed and a current density adapted such that each elementary diffraction grating (1061,1062) emits a Smith-Purcell radiation on the fundamental mode. The elementary diffraction gratings (1061,1062) interact with each other to reduce the saturation time necessary for the Smith-Purcell radiation to be produced.

Abstract: High-efficiency method and device, to produce coherent Smith-Purcell radiation. A conductive diffraction grating, delimited by two conductive walls, is used, and an electron beam is passed above the grating to generate the radiation. According to the invention, the speed of the electrons is sufficiently low in order that, in a diagram (wave number k, frequency f), the beam line (I) intersects a portion (V) of a branch of the dispersion relationship, located in the first Brillouin zone, and corresponding to the grating's fundamental mode, at a point (P) located outside the zone delimited by the light lines (III, IV), and the current density of the beam is sufficiently high to excite the grating's fundamental mode which is radiated towards the outside thereof.

Abstract: A microwave tube including: a) an electron gun capable of producing a beam of electrons in the form of a hollow axisymmetrical cylinder in repetitive operation; and b) a body in which the beam is intended to propagate, the body ending with a collector and being provided with means for applying an axial magnetic field for guiding the beam and, upstream from the collector, with a resonant structure crossed by the beam, intended to group the electrons into a succession of packets (P). The resonant structure is formed with two coupled cavities which follow along the axis (Z) of the beam, the coupling being achieved via an inter-cavity region crossed by the beam, this structure having axial symmetry the axis of which is that of the beam and being dimensioned so that the transformation of the electrons in packets is accomplished at a frequency which is that of the ? resonant mode of the resonant structure.

Abstract: A microwave tube including: a) an electron gun capable of producing a beam of electrons in the form of a hollow axisymmetrical cylinder in repetitive operation; and b) a body in which the beam is intended to propagate, the body ending with a collector and being provided with means for applying an axial magnetic field for guiding the beam and, upstream from the collector, with a resonant structure crossed by the beam, intended to group the electrons into a succession of packets (P). The resonant structure is formed with two coupled cavities which follow along the axis (Z) of the beam, the coupling being achieved via an inter-cavity region crossed by the beam, this structure having axial symmetry the axis of which is that of the beam and being dimensioned so that the transformation of the electrons in packets is accomplished at a frequency which is that of the ? resonant mode of the resonant structure.