D“- 24, 1946' c. E. DAWLEY ETAL 2,413,175 TRIGATRON TUBE Filed Sept. 27, 1944 14 22 INVENTOR C‘: E 017W‘ 5)’. BY ATI'ORNEY Patented Dec. 24, 1946 UNITED STATES PATENT OFFICE 2,413,175 TRIGATRON TUBE Clarence E. Dawley, Bloom?eld, N. 1., assignm to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 27, 1944, Serial No. 555,933 4 Claims. , (or. 250-215) 2 The present invention relates to discharge de inert gaseous ?lling so that "clean-up” of the vices and more particularly to a triggered spark gas does not occur and liquid electrodes are pro gap device constituting an improvement over the vided to prevent sputtering during the useful life structure shown and described in the copending of the device. application of E. G. F. Amott et al., Serial No. 5 Still further objects of the present invention 491,496, ?led September 19, 1943, assigned to the will become obvious to those skilled in the art same assignee as the present invention, and of by reference to the accompanying drawing which I- am one of the coinventors. wherein: ‘ The structure of the device as disclosed in such Figure 1 .is a sectional view in elevation of a copending application comprises an envelope 10 triggered spark-gap device constructed in ac provided with three electrodes, one of which is cordance with the present invention, and a triggering electrode, and ?lled with a rare gas including a small percentage of oxygen and at an atmosphere or more pressure. A voltage is Figure 2 is a view similar to Fig. l of a modi ?cation which the triggered spark-gap of the present invention may take. applied between two of the electrodes of insum Referring now to the drawing in detail, the cient magnitude to cause breakdown until a volt device as shown in Fig. 1 comprises an envelope age is applied to the trigger electrode. Upon the shown generally at 5 composed in part of a application of the triggering voltage, an are dis vitreous material in the form of an annular collar chargeoccurs between one of the high voltage 6, to the one end of which is sealed a spherical electrodes and the triggering electrode since the 20 metallic member ‘I having a coe?‘icient of expan latter is isolated from the other grounded high sion simulating that of the vitreous collar, such voltage electrode by suitable means such as a as the alloy known as “Kovar.” Also hermeti condenser. cally sealed to the other end of the vitreous collar Once such discharge is initiated between the 6 is a metallic ?anged member 8 having an an high voltage electrode and the trigger electrode, 25 nular re-entrant portion 9, which is likewise the latter immediately assumes a high voltage formed of “Kovar." and being positioned in such proximity to the A metallic support Ill, which may be of “Kovar” grounded eiectrode, this high voltage on the if desired is provided with a spherical end I! trigger electrode causes the arc discharge to concentric with the spherical member ‘i, which transfer to the grounded electrode enabling the 80 is welded, soldered or otherwise a?‘ixed at I3 to passage of several hundred amperes between the the reentrant portion 9 prior to sealing the me high voltage electrode and ground. tallic ?anged member 8 to the vitreous collar 6. The life of the device above noted is limited Although the metallic support i0 may be made by several factors, namely, cleaning up of the long enough so as to provide an extension beyond oxygen forming part of the gaseous medium 85 the exterior surface of the ?anged member 8. within the envelope, which occurs all through for assembly purposes it is preferable that it operating life of the device eventually decreasing extend only a short distance into the reentrant the breakdown thereof below its useful operating portion 9 as shown, for reasons which will here voltage. Also due to the large current passing inafter appear. through the tube, sputtering of electrode mate 40 An additional spherical metallic member rial occurs which accumulates on the cathode and triggering electrodes causing a change in the electrode spacings, thereby altering the char acteristics of the device. , The primary object of_ the present invention is to provide a device which eliminates the above I noted disadvantages, thus prolonging the useful life of a triggered spark-gap device. Another object of thepresent invention is the provision of a triggered spark-gap device in which a ?uid metal is employed as electrodes to eliminate sputtering of electrode material during the life of said device. ' Another object of the present invention is the provision of a spark-gap device‘ employing an formed of iron or steel and constituting the anode electrode ll of the device, is a?lxed to a tubular member or support ii of “Kovar,” with such support being hermetically sealed to a re entrant portion IG of a vitreous ?anged closure member ll. Hermetically sealed to the periph eral edge of such closure member is a "Kovar” sleeve l8. After sealing the support l5 and the “Kovar” sleeve i8 to the vitreous closure member ll, the support l5 together with the anode i4 is inserted into the metallic support l0 and when the spherical anode i4 is concentrically disposed relative to the metallic spheres 1 and i2, the sleeve i8 is welded or soldered at l9 to the "Kovar” ?anged member 8. Thus this sleeve is 2,418,175 3 to all intents and purposes is an extension of 4 . velopes to enable them to be screwed together as the metallic support III. shown in Fig. 2. The tubular support I5 is provided with an opening 20 which enables evacuation of the inte rior of the support l0, afterwhich it is filled with ’ ' As will be noted, the electrode support 31 has _ , a quantity of liquid metal such as mercury 22 aiiixed to its lower end a spherical electrode 42 of iron or “Kovar," which is concentrically dis posed relative to the spherical section 33, and in and an inert gas, such as a mixture of hydrogen like manner the upper envelope 32 has a spherical and argon at a pressure ranging from approxi electrode 43 concentric with the spherical section 33 thereof. After evacuation of the envelopes 33 mately a hundred atmospheres to an atmosphere or less, prior to sealing-off the end 23 of the sup 10 and 32, they are ?lled with an inert gas and a port l5. Similarly, the outer metallic spherical member ‘i is provided with a tubulation 24 to allow evacuation of the space between its interior surface and that of the support in with its spher ical end l2, after which it is ?lled with a small quantity of mercury or the like 25 and the same small quantity ‘of mercury 44 and 45, respectively, prior to sealing-on at 45. This modi?cation operates in the identical manner as previously described-relative to Fig. 1 in that a high voltage is impressed across the spherical electrode 43 and the grounded spherical section 33 of envelope 30. Upon the application of a trigger pulse of opposite sign to electrode support 39 joining with the spherical metallic It will thus be seen that the various metallic parts are electrically insulated from each other 20 section of the envelope 3: and which is appro priately isolated from ground, an arc appears be by vitreous portions of the envelope but are tween the electrode 42 and the mercury pool 44. readily accessible so as to enable the connection Inasmuch as electrode support 33 engages the lug of electrical conductors thereto. The small quan 40 carried by the spherical metallic section 33 tity of mercury 25 in contact with the spherical of envelope 32, the latter of which is contacted 25 end 1 constitutes the cathode electrode while the by the mercury pool 45 and hence may all be quantity of mercury 22 within the spherical end considered as one electrode, the full potential of I2 is the trigger electrode properly isolated from electrode 44 appears on the mercury pool 45 and ground and the sphere l4 the grounded anode. thus substantially simultaneously causes break A high voltage is applied across the anode l4 inert gas as above‘ mentioned, prior to sealing-off the tubulation 24. and cathode 25 which is insu?lcient to cause an 30 down of the gap between the mercury 45 and spherical electrode 43 causing passage of energy arc discharge. Upon the application of a high completely through the device from electrode 43 to the metallic spherical section 33 of envelope 30. Like in Fig. 1 the modi?cation of Fig. 2 will cathode 25 and the spherical end l2 supporting the mercury 22; and since the distance between 35 operate in any position from :90° to the vertical, and since the mercury 44 and 45 is struck by the the mercury pool 22 and the anode I4 is not sum arc discharge during operation, there is no sput cient to withstand the high voltage, the 'arc jump tering of the electrode material, which would across to the grounded anode [4 thus completes otherwise so accumulate as to alter the electrode the discharge from the cathode 25 to the anode 40 spacing with change in the operating charac l4. teristics of the device. By the utilization of concentric spheres, the It can thus be readily seen by those skilled in mercury 22 and 25, which constitute ‘in effect the the art that a triggered spark-gap is herein pro electrode surfaces, can rotate within an angle of vided in which sputtering of the electrode mate :90“ from vertical with the device being fully voltage pulse of opposite sign to the trigger elec trode 22, an arc discharge appears between the operable from one of these extreme positions to 45 rial is eliminated by the employment of a metallic liquid, such as mercury at the electrode surface the other. Moreover, the mercury does not sput impinged by the arc discharge, thus. presenting ter during operation as in devices of the prior a variation in electrode spacing during operation art but volatilizes only, returning to the pool upon of the device, which would otherwise affect the condensing. This, together with the employment of an inert gas which does not clean-up during 50 characteristics thereof. Moreover, by utilizing an inert gaseous environment in the device which operation, insure a relatively long useful life presents clean-up of the gas together with the without variation in the operating characteristics elimination of sputtering, the useful operating due to a change in electrode spacing or gas life of the device is considerably increased over pressure. The modi?cation as shown in Fig. 2 differs 65 similar devices of the prior art. Although two embodiments of the present in slightly from that of Fig. 1 in that it is of tandem vention have been shown and described, it is to construction being formed of two substantially be understood that still further modification identical devices joined together. In the main, thereof may be made without departing from the the construction is similar to that of Fig. 1 since it includes an envelope shown generally at 30 and 60 spirit and scope of the appended claims. I claim: 32, and as each envelope is of identical structure, 1. A spark-gap device for supporting a high a detailed description of one should sui?ce. voltage are discharge comprising an envelope The envelopes 30 and 32 are formed of a spheri provided with an inert gaseous medium and a cal metallic section 33 of “Kovar” or the like and hermetically sealed to a vitreous annular collar 65 plurality of concentrically disposed spaced spher ical electrodes including an anode, a cathode, 34. Sealed to the opposite end of such vitreous and a trigger electrode operable upon the appli collar 34 is a metallic ?anged member 35 having cation of a high voltage pulse thereto to cause a reentrant portion 36. Prior to scaling in the an arc discharge between the trigger electrode ?anged member 35 to the collar 34, a metallic electrode support 31 is soldered or welded at 38 70 and said cathode and an attendant substantially instantaneous initiation of an arc discharge with to the ?anged member 35, with the outer end of said anode; and a quantity of liquid metal in the support 31 protruding above the surface of contact with said spherical trigger electrode and the ?anged member and being threaded at 39 so said spherical cathode respectively and consti as to engage an internally threaded metallic lug 40 secured to the metallic section 33 of the en 75 tuting the surface of each electrode impinged by 5 2,418,175 the resulting arc discharges. thus eliminating sputtering of electrode material otherwise oc curring from the electrode surface impinged by the arc discharge with an attendant variation in electrode spacings and operating characteristics which destroy the useful life of the device. 2. A spark-gap device for supporting a high voltage arc discharge comprising an envelope provided with an inert gaseous medium and a plurality of concentrically disposed spaced spher electrodes with substantially simultaneous in itiation of an arc discharge between the remain der of said electrodes, and a quantity of liquid metal in contact with at least two of said spher ical electrodes and constituting the surface of each said electrode impinged by the arc discharge during operation, thus eliminating sputtering of electrode material otherwise occurring from the electrode surface impinged by the arc discharge with an attendant variation in the electrode ical electrodes including an anode, a cathode, spacings and operating characteristics which de and a trigger electrode operable upon the ap stroy the useful life of the device. . plication of a high voltage pulse thereto to cause 4. A spark-gap device for supporting a high an arc discharge between the trigger electrode voltage arc discharge comprising an envelope and said cathode and an attendant substantially 15 provided with an inert gaseous medium therein instantaneous initiation of an arc discharge with and ‘a plurality of concentrically disposed spaced said anode; and a quantity of mercury within spherical electrodes including an anode, a cath said spherical trigger electrode and within said ode, and a trigger electrode with said cathode spherical cathode and constituting the surface and trigger electrode forming a portion of the of each electrode impinged bythe resulting arc 20 envelope walls and hermetically sealed to vitre discharges to eliminate sputtering of electrode ous insulating portions of said envelope; said material otherwise occurring from the electrode trigger electrode being operable upon the appli surface impinged by the arc discharges with an cation of a high voltage pulse thereto to cause attendant variation in electrode spacings and op an arc discharge between the trigger electrode erating characteristics which destroy the useful 25 and said cathode and an attendant substantially life of the device. instantaneous initiation of an arc discharge with 3. A spark-gap device for supporting a high said anode, and a separate quantity of mercury voltage are discharge comprising an envelope in contact with said trigger electrode and with provided with an inert gaseous medium therein said cathode and constituting the surface thereof and a plurality of concentrically disposed spaced impinged by the arc discharge during operation, spherical electrodes forming a portion of said thus eliminating sputtering of electrode material envelope walls and hermetically sealed to vitre otherwise occurring from the electrode surface ous insulating portions of said envelope, one of impinged by the arc discharge with an attendant said electrodes constituting a trigger electrode variation in the electrode spacings and operating operable upon the application of a high volt characteristics which destroy the useful life of tage pulse thereto to cause an arc discharge be 35 the device. tween said trigger electrode and another or said CLARENCE E. DAWLEY.