Abstract: A cathode ray tube is provided with an electron gun which comprises a cathode structure which contains an electron-emitting material at an end portion and in which a heating element of bifilarly wound wire is accommodated. Except in the vicinity of the ends of the wire, said wire is provided with an electrically insulating layer (46) whose radius decreases, near the transition between the covered wire and the uncovered ends, by at least 15%, preferably at least 30%. Preferably, the layer (46) having the reduced radius continues for at least 100 .mu.m in the direction of the transition (54). The distance between the transition (54) and the electric connection (61) is smaller than 250 .mu.m, preferably smaller than 150 .mu.m. As a result, the number of uncovered turns between the electric connection (61) and the transition (54) is reduced to below five.

Abstract: A method of manufacturing a dispenser cathode, in which method a powder of a refractory metal and a scandium-containing powder are mixed with each other and pressed to form a cathode body. According to the invention at least both these powders and a suitable binder are mixed with each other to form a homogeneous suspension prior to the pressing operation and the whole mixture is subsequently cured and ground to granules having a larger average size and hence a greater fluidity than the grains of the starting powders. Subsequently the granules thus obtained are pressed to form a cathode body (2). The invention leads to a better processibility and greater convenience of handling of the starting powders so that notably very fine staring powders can be used, which results in cathodes (1) having a better recovery after ion bombardment as compared with cathodes manufactured in conventional manners which are necessarily based on relatively coarse powders.

Abstract: Electron-optical device having two elongate emitting regions arranged symmetrically with respect to a longitudinal axis for producing two electron beams having an elongate cross-section. By means of electron grids, the two beams are focused at the same point of an electron target arranged transversely to the longitudinal axis and having a short central axis and a long central axis. The elongate emitting regions have their smallest cross-section parallel to the scanning direction of a device, cooperating with the electron-optical device, for scanning a target arranged transversely to the longitudinal axis.

Abstract: A method of manufacturing a dispenser cathode, in which method a powder of a refractory metal and a scandium-containing powder are mixed with each other and pressed to form a cathode body. According to the invention at least both these powders and a suitable binder are mixed with each other to form a homogeneous suspension prior to the pressing operation and the whole mixture is subsequently cured and ground to granules having a larger average size and hence a greater fluidity than the grains of the starting powders. Subsequently the granules thus obtained are pressed to form a cathode body (2). The invention leads to a better processibility and greater convenience of handling of the starting powders so that notably very fine starting powders can be used, which results in cathodes (1) having a better recovery after ion bombardment as compared with cathodes manufactured in conventional manners which are necessarily based on relatively coarse powders.