William Wilson

“ Houskeeper adopted into the construction of the tube a remarkable type of vacuum seal which he had previously developed. These seals are made between glass and metal and can be amde in any desired size. They are capable of withstanding repeated heating and cooling over wide ranges of temperature, from that of liquid air to 350° C, without cracking and without impairment of their vacuum holding properties. ”

“ The usual type of vacuum tube consists of an evacuated glass vessel in which are enclosed three elements, the filament, the plate, and the grid. When the tube is in operation an electron current flows between the filament which is heated by an auxiliary source of power and the plat, the magnitude of this current being controlled by the grid. ”

“ The principles involved in the making of the disc seal are the same as those involved in making the ribbon seal. If a metal disc is sealed wholly into glass the edges must be sharpened or the glass and copper break away from each other as in the case of the ribbon seal. ”

“ It has been found necessary for instance to suspend the anode in gimbals during the making of the tube seal owing to its great weight, and special devices have been made to hold the filament grid assembly in place while it is being sealed in, otherwise the strains produced by its weight cause cracking of the seal. ”

“ The anode consists of a copper tube 1.5′′ in diameter and 7.5′′ long. A copper disc is welded to one end forming a vacuum tight joint. The other end which is turned down to a knife edge is fused directly to a glass tube. ”

“ The anode which is made of a piece of seamless copper tubing closed by a copper disc welded into the end, is 14′′ long and 3.5′′ in diameter. The filament is of tungsten and is .060′′ in diameter and 63.5′′ long. The current required to heat it is 91 amperes and the power consumed in it 6 k. w. The filament leads are of copper red one eighth of an inch in diameter and are sealed through 1′′ copper disc seals. The grid is of molybdenum and is wound around three molybdenum supports. ”

“ This furnishes the means of joining metal and glass tubes end to end and is used in the water-cooled tube to attach the anode to the glass cylinder which serves to insulate the other tube elements. As in the case of the disc seal, it can be made either with the edge of a metal not in contact with the glass, as shown at A, or with the metal sharpened to a fine edge which is in contact with the glass. ”

“ The importance of the problem, however, was such that Stoekle and Buckley pushed on in the face of difficulties to the construction of tubes which could handle kilowatts where previous tubes could only handle watts. ”