Abstract: In a power electronic tube the outer surface of the collector is in the shape of a cylinder and has equidistant grooves formed in cross-sections and along the generatrices of this cylinder, which gives them flexibility and allows assembly with an insulating sleeve.

Abstract: A delay line for a high frequency tube that is cooled by circulating fluid.The cooling fluid circulates in a duct (FIG. 3, 10), formed in the space between two sleeves (8 and 9). The sleeves are of non-magnetic material, impervious to the cooling fluid, and have an axis parallel to the axis of the delay line. The first sleeve (8), is vacuum tight, brazed or hard soldered to dielectric supports (2) and, in cross section connects two adjacent supports in a straight line. The second sleeve (9), is cylindrical, and contains the first sleeve to which it is brazed at several points. A focusing device made of permanent magnets is mounted on the second sleeve.The invention will find use in high frequency tubes.

Abstract: An helical type line for travelling wave tube, with a variable diamter. The line is made on a skew surface constituted by a revolution surface on which flat surfaces have been made. The variation of the line diameter may be carried out by a variation of the revolution surface diameter, the flat surfaces being parallel to the axis of the revolution surface. That variation may be also carried out by a variation of the angle made by the flat surfaces in relation to the helix axis, the revolution surface being cylindrical.