Abstract: The invention is applicable to matrix detector or display screens formed by assembling several elementary screens. A matrix screen according to the invention comprises several elementary screens (E1 to E4) spliced together on one of their edges (10, 11). According to the invention, each elementary screen (E1 to E4) includes a mechanical stop device (B1 to B4) which mates with a mechanical stop device on an elementary screen to which it is spliced so that the two elementary screens are positioned relative to each other. This arrangement avoids long and difficult alignment and indexing during the assembly of the elementary screens (E1 to E4) since these operations are completed when the elementary screens are cut, this operation itself requiring the use of accurate alignment and indexing tools.

Abstract: The disclosure relates to display sets wherein the image produced by a cathode-ray tube is displayed on a display screen by means of an optical device. It relates more particularly to means for facilitating the relative positioning between the cathode-ray tube and the optical device. The cathode-ray tube comprises a bulb having one end closed by a transparent plate bearing an cathodoluminescent screen. In one characteristic, the transparent plate is greater than the bulb and comprises a peripheral part that extends beyond the bulb so as to constitute a reference marker of the position of the cathodoluminescent screen. FIG. 1.

Abstract: The disclosure relates to image intensifier tubes of the proximity focusing type, wherein it especially concerns the positioning of a primary screen with respect to a slab of microchannels. An image intensifier tube comprises a sealed chamber containing a primary screen and a slab of microchannels. The slab of microchannels is fixed to the body of the chamber. According to one characteristic, the primary screen is fixed to the slab, from which it is kept at a distance by means of at least one insulating shim. The result thereof is greater precision and greater uniformity of the spacing between the primary screen and the slab of microchannels.

Abstract: The invention relates to display screens of the plasma panel type. Its subject is more particularly electrically insulating elements such as spacers (12, 15) and/or dielectric layers (4, 6).According to the invention, the spacers (12, 15) and/or the dielectric layers (4, 6) are produced from a polymerizable organic compound.It results therefrom that the highest temperature imposed on the plasma panel during its manufacture can remain lower than a temperature of the sealing of this panel.

Abstract: A cooling device for microwave tubes includes a cold part and a heat-conducting member having a first surface in contact with a surface of the cold part. A second surface of the heat-conducting member is in contact with an envelope of the tube. The surface of the cold part and the first surface of the heat-conducting member are respectively concave and convex. The device can be applied to the cooling of microwave tubes including klystrons, travelling-wave tubes and gyrotrons.

Abstract: The invention relates to a manufacturing process for an impregnated cathode for an electron tube and the impregnated cathode obtained in this manner. The method consists in mixing (b) a powder (Y) containing the emissive elements (generally barium and calcium aluminates) with powder (W) of at least one refractory metal (generally tungsten, if necessary mixed with a platinum ore metal), then pressing (c) this mixture into a pellet (1) which is then sintered (d) at a high temperature in hydrogen (approx. 2000.degree. C.). In the prior art of this method, a powder of at least one refractory metal was pressed and sintered and then impregnated, machined, cleaned, etc. The process according to the invention therefore saves many steps in the manufacture of an impregnated cathode with respect to the prior art.

Abstract: An X-ray image intensifier tube includes a scintillator screen for converting ionizing radiation into light radiation or near-visible radiation, a microchannel array for achieving electron multiplication, and a photoelectrode positioned directly on an input face of the microchannel array. The input face of the microchannel array is coated with an electrically conductive layer which directly contacts the photocathode. The present design eliminates strict spacing requirements between the photocathode and the microchannel array and allows the photocathode and the microchannel array to operate at a single potential rather than requiring separate potentials. The requirement of a separate support for the scintillator screen is also obviated since the scintillator screen is formed on the input face of the microchannel array.

Abstract: A power amplifier valve with a grid is disclosed having improved reliability of operation and lifetime of the valve. A screen grid of a tetrode has a mesh grid with vertical or oblique rods in pyrolytic graphite. According to the invention, the rods are provided with a greater width at the bottom of the grid near the output of the valve where the high-frequency currents are greatest.

Abstract: The disclosure relates to radiological image intensifier tubes, and more particularly to means to improve the image resolution of these tubes and/or correct their brightness curve at output. The image intensifier tube comprises an input screen comprising a scintillator borne by an aluminium substrate. A porous layer of alumina is interposed between the scintillator and the substrate. The alumina layer is dyed so as to absorb the light emitted by the scintillator towards the substrate.

Abstract: An electron gun is modulated by an optoelectronic switching device. This switching device comprises a modulated light source and at least one GaAs or Si solid-state optoelectronic switch, this switch being non-conductive when not illuminated and conductive when illuminated by the modulated light source; the device also includes components to transmit the light from the source to the switch(es). In one embodiment, the modulated light source is a laser and in a second embodiment the source is a continuous source externally modulated by a mechanical or electrooptical device. The optoelectronic switching device is connected between a high-voltage source and the cathode of an electron gun, thus modulating the cathode.The invention is particularly applicable to microwave electron tubes.

Abstract: In an X-ray image intensifier tube, a casing for the protection from x-radiation from the X-ray image intensifier tube. The casing according to the present invention comprises a jacket of a thermoplastic material charged with a powder of a material that absorbs the x-radiation and a shielding from outside magnetic fields. The shielding is in contact with the jacket. The screen that absorbs the x radiation thus is at least partially formed of the jacket.

Abstract: The invention is a mode converter and power splitter device for electron tubes, particularly gyrotrons and tubes of similar categories. These tubes have an output cavity 2, which is a circular form about a centerline, and a hollow electron beam 1 which propagates along the same centerline. The device complying with the invention is a structure which comprises secondary wave guides 6, symmetrical in azimuth around the same centerline as the outlet cavity, each guide 6 containing coupling apertures 7 on its outer wall (that furthest from the centerline), these apertures 7 being arranged to excite a given mode in the guide. One important embodiment of the invention is that the electron tube operates in a TE.sub.m,n mode with a high azimuth index m and the number of secondary guides 1=m. Another important embodiment of the invention is that secondary guides 6 are trapezoidal in section. Another important embodiment of the invention is that secondary guides 6 are excited in the fundamental mode.

Abstract: Disclosed is a directional coupler on a mirror elbow for a microwave transmission line sized to convey very high power. The coupler consists of a main guide with a mirror elbow and at least one secondary guide. The secondary guide is joined by one of its walls to the external surface of the mirror, and the interior of the secondary guide is joined to the interior of the mirror elbow by coupling holes.

Abstract: An image intensifying tube, such as a image intensifying tube which converts X-rays into a visible image, comprises a curved input screen which comprises a substrate that receives input radiation and a photocathode supported on the substrate, and an output screen which converts the electrons emitted by the photocathode into a visible image. In order to compensate for changes in luminosity due to the curvature of the input screen, an intermediary layer of radially variable thickness is deposited between the substrate and the photocathode. The intermediary layer is made from a material, such as indium oxide (In.sub.2 O.sub.3), which modifies the electron emitting characteristics of the photocathode as a function of the thickness the intermediary layer. Thus, a thicker intermediary layer near the center of the input screen will compensate for reduced luminosity at the edges of the screen.

Abstract: A image intensifier tube, having its brightness curve corrected in a simple way. The image intensifier tube comprises an input window (3), and an output window (4) at which the brightness is measured. The output window (4) bears a device for the attenuation of light (20), the opacity of this device being greater in a central zone (0) than it is towards the edges (21).

Abstract: Disclosed is a microwave tube with n (where n is an integer greater than one) longitudinal electron beams parallel to an axis XX'. It has at least one output cavity crossed by the electron beams and one collector collecting the n electron beams at their output from the cavity. A transmission line is coupled to the output cavity. The transmission line is coaxial with the axis XX'. The collector is positioned around the transmission line and is coaxial with it. The device can be applied to multiple-beam klystrons capable of working at high power and at high frequency.

Abstract: Disclosed is a method for the control of display screens that can be applied to internal memory type screens, notably plasma display panels for which it increases the dynamic range of the adjusting of the luminosity. This method consists in controlling the cells (C1 to C16) of the screen by means of addressing commands, each one of which comprises a selective command and a semi-selective command. According to one characteristic, for the addressing of one and the same line (L1 to L4) of cells (C1 to C16), the method consists in separating the selective command (CI) from the semi-selective command (CE) by an adjustable interval of time (PL1 to PL4).

Abstract: Disclosed is a microwave tube with n (where n is an integer greater than one) parallel, longitudinal electron beams distributed on a ring centered on an axis XX'. The electron beams go through several groups of n cavities. So that each group may resonate on a single frequency, it is provided that the cavities of one and the same group will work in their dominant mode, at one and the same frequency, and will get excited in phase. To this end, the cavities of the input group are excited in phase by an appropriate device external to the tube. The device can be applied to multiple-beam klystrons working at high frequencies.

Abstract: An electron tube with concentric, cylindrical electrodes has at least one meshed type of grid, a mesh being defined by several rods in contact by their ends, each point of contact forming a node. In order to limit the grid current, the surface area of a node is reduced. Only three rods leave each node. The meshes are hexagonal.

Abstract: A klystron with widened instantaneous passband comprises a succession of cavities separated by drift tubes, divided into three blocks. The first block comprises all that is upline from a first central cavity, the third block comprises all that is downline from a second central cavity and the second block comprises the central cavities. In each block, the sum of the lengths of the drift tubes is equal to: H+(T.times.180.degree.). H is a quantity ranging from 45 to 135 plasma degrees and T is an integer greater than or equal to zero. In at least one of the blocks, T is greater than or equal to one and the length of at least one tube of this block is greater than or equal to 135 plasma degrees. The disclosed device can be applied to wideband klystrons.