Nov. 26, 1946. F. D. GOODCHILD _ 2,411538 _ELECTRON DISCHARGE APPARATUS Filed June 25, 1941 ' / //// //// / ////'//////.///// ? ?`?...?3§š__ _ ` .. B; I //// / //?//// / 1 ////// // // A Fig. 2. / //////////`/›///////////////////// ?/?? m\ // ???_4_. /// /////////////?////////////////// I ???? ???? Já. MM' by , &4115538 Patented Nov. 26, 1946 ' UNITED STATES einem' oFF?cef'f ËLECTRON DISCHARGËVVAPPARATUS ` › " “Frank, Douglas Goodchíld, London, England, as signor to International Standard _Electricjco'r- ' r'poration, New i?irk,` N. Y. › ~_ Application J'une 25,*1941, Serial No. 3995997 In Great Britain June 21, 19510. 1 Claim. (Cl. aso-27.5) 2 1 This invention relates to electron discharge ap paratus incorporating high frequency resonators of coaxial-conductor type and to insulating seals for co-axial conductors. _ In co-pending U. S. application Ser. No. invention for making a seal for bringing a co axial conductor transmission line out of an evac uated envelope will now be described with refer ence to Figs. 1 and 2 of the accompanying draw ing. In the ?rst ?gure there is shown a length of co-axial conductor transmission line comprising British Patent No. 531490, June 24, 1941, various a Copper tube A and a centre rod B; C is a but electron discharge devices are disclosed compris ton of glass and D a stem sealed to the outside of ing lengths of co-axial conductor line constituting Very high frequency resonators and means for 10 the tube and adapted to be sealed in known man ner in a bulb which in the present case surrounds passing electron beams through the ?elds of the the tube A. 'The Copper tube A is machined resonators for the Velocity modulation of the 361401, ?led November 27, 1940, corresponding to electrons. i In such arrangements, and generally where co ' down to a wall thickness ,of 0.015" in the region of the _glass button and is feathered in the well axial-conductor-type resonators are employed as 15 known manner at the point where the stem is frequency determining circuits interacting di rectly with electron streams in electron discharge apparatus, it is desirable to provide means for tuning the resonator and a convenient way of › sealed on the outside. The method_ of manufacture will be clear from the second ?gure. A short tube of glass shown at F is sealed to the inside of the copper_ tube external heat together with the application of doing this is to vary the electrical length of the 20 by' a, paddle to the inside to knead the glass down conductors, that is, the sp-acing between nodal . on to the Copper wall. A bead of glass is also points. Obvious difficulties immediately arise if fused to the centre rod at G. Both?these small the resonator is wholly contained within an en pieces of glass are heated simultaneously and velope. Diñiculties also arise in reducing radia while still molten the rod is pushed into the tube tion loss to a ?satisfactorily small value if the 25 so that the two pieces of glass are joined to co-axial conducto-rs are split into mechanically gether. ' separate parts respectively inside and outside the The rod_ B may be wholly of Copper of uniform , envelope, these difficulties arising mainly because diameter or the part passing through the glass of the necessity' of a glass or other partiticn be- e tween the parts. i 30 button may be a squirrel cage structure or a The invention in one aspect thereof resides in an electron discharge device comprising co-axial conductors sealed in a, vacuum tight glass enve Copper sheath as will be clear from the disclo glass bead on to the inner conductor and insert ing the inner conductor into the outer conductor while the glass ring and the glass bead are molten and B are provided with apertures K in a com mon diameter and ?ns L in the apertures and projecting from a part M of the wall which serves to collect the electrons. A cathode N and_ a sures in British Patent No. 538,485, August 6, 1941. It is also possible for the rod to be of tungsten and the glass bead of hard glass. lope, electrodes within the envelope adapted to set In Fig. 3 of the accornpanying drawing is shown up an electron beam traversing the ?eld of the 35 a díscharge device utilising the principles of elec co-axial conductors for the direct interaction of tron velocity modulation and incorporating a co the electrons and the ?eld and means Operating axial-conductor-type resonator. The device em upon the part of the co-axial conductors outside bodies theseal described with reference to Figs. the envelope for Varying the electrical length of 1 and 2, and shows by way of example how the 40 said conductors. ` co-axial concluctors may be brought out from The invention also resides in a, method of mak the evacuated envelope and tuned by means ex ing an insulating sea? between co-axial con ternal to the envelope. ductors consisting in fusing a glass ring on to the Referring to Fig. 3 the co-axial conductors A inner surface of the outer conductor, fusing a I so that these glass parts become united. ' A better understanding of this -invention will fccussing electrode O are required outside the be had from the particular description thereof 50 tube A opposite the aligned apertures. These constructiona? features› and the principles of op made with reference to the accompanying draw eration for the generation of high frequencies are ing, in which Figs. 1 and 2 illustrate the method vfully described inøthe above mentioned_U. S. ap of making the seal, and .Fig. 3 shows the com plication Ser. No. 367 ,401. pleted tube structure. The preferred method in accordance with the 55 The co-aXial conductors extend through the" '2,411,538 3 4 stem E, the sealing arrangeinents being as al ready described. The frequency of oscillation tight envelope and having aligned apertures, part depends upon the length of the conductors be tween short-circuiting conductive b?ridging mem of said coaxial conductors being outside said en velope, electrodes within the envelope in line with bers. One of these conductive bridging members is constituted by a plunger or piston H slidable within the part of the tube A and along the part of the rod B which projects through the stem E. Any convenient screw or other adjusting mech anism may be provided for the arrangement provides continuous the Operating frequency with a quencies. Modi?cations within the scope plunger. The adjustment of range of fre of the inven tion as well as different applications of the fea tures claimed will be readily appreciated. What is claimed is: conductors' s'ealed substantially within a vacuum 5 said apertures and adapted to set up an electron beam traversing the apertures of the co-axíal conductors for the velocity modulation of the electrons an annular insulating seal between the inner conductor and an intermediate portion of the outer conductor of reduced wall thickness a coaxial sea] between an end of the outer con ductor and a glass tube forming part of the en velope, and adjustable means within the part of one of the co-axial conductors outside the enve› 15 lope for Varying the electrical length of said con ductors. › v Electron discharge device comprising co-axia] FRANK DOUGLAS GOODCHILD.