Abstract: A radiation source includes a vacuum chamber, means for injecting an optical wave, a cold source for emitting electrons, a power supply, an anode for emitting X-rays, and at least one window through which the X-rays exit. A light source delivers the optical wave, and the cold source includes at least one substrate with a conducting surface and is subjected to an electric field. The cold further includes a photoconductive element in which the current is controlled approximately linearly by the illumination and at least one electron-emitting element, the photoconductive element electrically connected in series between an emitting element and a conducting surface. Current photogenerated in the photoconductive device is equal to that emitted by the emitter or the group of emitters with which it is associated, and the emitted stream of X-rays is approximately linearly dependent on the illumination.

Abstract: In an optically controlled cold-cathode electron tube, the emitters 1, of nanometer and/or micron size and of elongate shape, have a structure comprising a first material (4) of sp2-bonding carbon type and a metallic second material (3), said first material being in contact with and surrounding said second material at its top and over the entire length of the emitter or at least part of said length starting from its top toward the base (b). The second material has a plasma frequency substantially equal to or greater than the frequency of the optical control wave.

Abstract: The invention relates to an optically-controlled field-emission cathode, comprising a substrate (10, 20, 30, 40, 50, 60, 70, 80, 90, 100) having at least one conducting surface (11, 21, 31, 41, 51, 61, 71, 81, 91, 101) and at least one conducting emitter element (16, 26, 36, 46, 56, 66, 76, 86, 96, 106) in the vicinity of a conducting surface, characterized in that it also comprises at least one photoconducting element (13, 23, 33, 43, 53, 63, 73, 83, 93, 103) electrically connected in series between at least one emitter element and a conducting surface of the substrate. Another subject of the invention is an amplifier tube comprising such a cathode. The application is for Vacuum tubes, in particular for microwave amplification, with a view for example to applications in telecommunications.

Abstract: A radiation source includes a vacuum chamber, means for injecting an optical wave, a cold source for emitting electrons, a power supply, an anode for emitting X-rays, and at least one window through which the X-rays exit. A light source delivers the optical wave, and the cold source includes at least one substrate with a conducting surface and is subjected to an electric field. The cold further includes a photoconductive element in which the current is controlled approximately linearly by the illumination and at least one electron-emitting element, the photoconductive element electrically connected in series between an emitting element and a conducting surface. Current photogenerated in the photoconductive device is equal to that emitted by the emitter or the group of emitters with which it is associated, and the emitted stream of X-rays is approximately linearly dependent on the illumination.

Abstract: In an optically controlled cold-cathode electron tube, the emitters 1, of nanometer and/or micron size and of elongate shape, have a structure comprising a first material (4) of sp2-bonding carbon type and a metallic second material (3), said first material being in contact with and surrounding said second material at its top and over the entire length of the emitter or at least part of said length starting from its top toward the base (b). The second material has a plasma frequency substantially equal to or greater than the frequency of the optical control wave.

Abstract: An optical structure enabling properties of the surface plasmons to be used is defined from a substantially binary, parameterizable unit pattern ME. The parameters a, b, c, d and hg of the pattern are chosen so as to maximize the complex amplitudes of the first two harmonics of the complex Fourier series describing the pattern ME. This structure is advantageously used in combination with a photodetector, an infrared or Terahertz optical wave emitter, or a field emission device.

Abstract: The invention relates to an optically-controlled field-emission cathode, comprising a substrate (10, 20, 30, 40, 50, 60, 70, 80, 90, 100) having at least one conducting surface (11, 21, 31, 41, 51, 61, 71, 81, 91, 101) and at least one conducting emitter element (16, 26, 36, 46, 56, 66, 76, 86, 96, 106) in the vicinity of a conducting surface, characterized in that it also comprises at least one photoconducting element (13, 23, 33, 43, 53, 63, 73, 83, 93, 103) electrically connected in series between at least one emitter element and a conducting surface of the substrate. Another subject of the invention is an amplifier tube comprising such a cathode. The application is for Vacuum tubes, in particular for microwave amplification, with a view for example to applications in telecommunications.

Abstract: An optical structure enabling properties of the surface plasmons to be used is defined from a substantially binary, parameterizable unit pattern ME. The parameters a, b, c, d and hg of the pattern are chosen so as to maximize the complex amplitudes of the first two harmonics of the complex Fourier series describing the pattern ME. This structure is advantageously used in combination with a photodetector, an infrared or Terahertz optical wave emitter, or a field emission device.

Abstract: Electrochemical sensor for the concentrations of species in a fluid mixture comprising a measuring cell of the type having a partial pressure internal reference electrode incorporating a catalysis region in which the gaseous mixture is brought into thermodynamic equilibrium and functioning according to the so-called "assay" process, so that only a small quantity of the gaseous mixture to be analyzed is admitted into the sensor. It also comprises a supplementary cell functioning as an ionic pump, so as to continuously modify the composition of the gaseous mixture admitted into the sensor under the control of a regulatable electric current.