A travelling-wave tube comprising a helix joined by posts to a vacuum chamber, each post made of electrically insulating material being covered by an electrically conductive material, of electrical conductivity comprised between 1000 and 100000 S.Math.m−1, over a portion of the post extending from the end of the post joined to the helix to the end of the post joined to the vacuum chamber and corresponding to a height comprised between 10% and 50% of the post.

A travelling-wave tube comprising a helix joined by posts to a vacuum chamber, each post made of electrically insulating material being covered by an electrically conductive material, of electrical conductivity comprised between 1000 and 100000 S.Math.m1, over a portion of the post extending from the end of the post joined to the helix to the end of the post joined to the vacuum chamber and corresponding to a height comprised between 10% and 50% of the post.

A depressed collector, comprises an insulator body; a plurality of serial electrodes, each serial electrode having a serial electrode receptor portion inside the insulator body and having a serial electrode thermal fin portion passing through and extending outside the insulator body; and a terminal electrode having a terminal electrode receptor portion inside the insulator body and having a terminal electrode thermal fin portion passing through and extending outside the insulator body.

A depressed beam collector and an RF source comprising a depressed beam collector. The RF source may include, e.g., a multi-beam klystron, a single beam klystron, or other RF sources having an electron gun. The beam collector collects spent electrons from the electron gun and comprises a grounded portion configured to collect a portion of electrons entering the collector and a biased portion configured to collect another portion of the electrons entering the collector and having a depressed energy.

A collector for a traveling wave tube has at least two stages and an entrance opening for receiving an electron beam, which is followed by a first collector stage, wherein the first collector stage including magnetic focusing and a final collector stage being electrostatically designed, wherein a high-voltage connection of the first collector stage is led radially outwards in the region of the first collector stage adjacent to the final collector stage or adjacent to one or more further collector stages via a high-voltage feedthrough radially outward, wherein a ceramic insulation sleeve is connected to an outer side of an electrode of the last collector stage immediately adjacent and free of high-voltage feedthroughs.