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Nov. 8, 1938. w. HAGEN ET AL 2,135,661 GASEOUS ELECTRIC DISCHARGE DEVICE Filed Jan. ll, 1937 F v on ?IgV’,AIW4FI/mCE. 02i 2 gi‘l-"231’! a 5 7 w 3 “ mHTjm eAgVi-O mnN26Rm aln 6%nr W mHo.hmnm?W/?o E 2 e it Patented Nov. 8, 1938 2,135,661 UNITED STATES PATENT OFFICE 2,135,661 GASEOUS ELECTRIC DISCHARGE DEVICE Wilhelm Hagen, ‘Berlin, and Wolfgang Thouret, Berlin-Wilmersdorf, Germany, assignors to General Electric Company, a corporation of New York Application January 11, 1937, Serial No. 120,066 In Germany January 15, 1936 1 Claim. (01. 176-126) ' The present invention relates to gaseous elec tric discharge devices generally and more par ticularly the invention relates to vapor discharge lamp devices operating with elevated container 5 temperatures and with correspondingly elevated vapor pressures, such as a vapor pressure in the order of atmospheres, similar to those disclosed in co-pending application, Serial No. 104,312, filed October 6, 1936, the inventors being Marcello 10 Pirani, Robert Rompe and Wolfgang Thouret. The gaseous electric discharge lamp devices disclosed in the co-pending application referred to above comprise a pair of electrodes centrally mounted in an elongated container and separated 15 a distance less than the diameter of the container. The current leads supporting the electrodes ex tend a substantial distance into the container, and consist of high melting point material such as tungsten or molybdenum. The container is of 20 small size and consists of a vitreous material, such as fused silica, capable of withstanding the high temperatures. Due to the different co e?icients of expansion of the vitreous material and the metal it is desirable to use graded seals for 25 such devices. ' The object of the present inventionis to pro vide a gaseous electric discharge lamp device of the above type which comprises means of simple structure for protecting the part of the current 30 leads inside the lamp container from the e?ects' of the gaseous electric discharge. Another ob Ject of the invention is to provide a gaseous elec distance into the container and terminates ad J'acent the electrode mounted on the end of the current lead. We have observed that no diminution in the quantity of vaporizable material available for ' 5 the discharge takes place in a gaseous electri'c. discharge lamp'device embodying the present in- \ vention even after the device has been operating for several hundred hours. In many cases this is of importance,_ for example, when a limited 10 quantity of merc1u~y is introduced into the lamp during the manufacture thereof in order to vob tain an unsaturated, vapor pressure when the lamp is at operating equilibrium. Any loss in the quantity of vaporizable material in the dis- 15 charge chamber of a device so constructed would, of course, change the electrical character istics of the device, which is undesirable. While this is apt to be a source of dif?culty in devices having protruding seals it does not take place in 20 devices embodying the present invention due to the fact that the electrode is closer to the end of the insulating sleeve than to the end of the con tainer and consequently the end of the sleeve is at a higher temperature during the operation of the 25 device than the end of the container. Any con densation of mercury vapor therefore takes place at the end of the container where it is available for the discharge rather than in the,sleeve where it is not available for the discharge. 30 In the drawing accompanying and forming part of this speci?cation a gaseous electric discharge lamp device embodying the invention is shown. in which Fig, 1 is a side elevational view of a. gaseous elec- 35 tric discharge lamp device of the ‘above type which is simple in structure and is inexpensive 35 to manufacture. Still further objects and ad— vantages attaching to the device and to its use tric discharge lamp device, and and operation will be apparent to those skilled in Fig. 2 is a sectional view of one end of the the art from the following particular description. _ lamp shown in Fig‘. 1. The invention attains its objects by surround Referring to the drawing the gaseous electric 4() ing the internal part of the current'lead with a discharge lamp device comprises an elongated, 40 tube or sleeve of high heat resisting, insulating tubular, quartz container I having a pair of cur material, such as quartz, the internal diameter of which closely approaches the diameter of the current lead extending therethrough to insure 45 protection of the current lead from the gaseous electric discharge. ‘The lead protecting sleeve is part of the stem structure of the lamp which stem consists of the aforesaid sleeve, a graded joint fused to the end of and hermetically closing the 50 end of said sleeve and a current lead fused into said joint and extending through and beyond said sleeve. In the manufacture of the device the stem structure is ?rst fabricated and the sleeve is then fused to the container to make an hermetic joint therein. The sleeve extends a substantial rent leads 4 sealed therein, one at each end thereof. Said current leads 4 ‘consist of a high melting point material, such as tungsten. Said container i has therein a starting gas, such as argon, and a quantity of vaporizable material, such as mercury, the vapor of which is luminosity producing during the operation of the device. An electrode 5 is mounted on each of said leads Or 0 4. Each of said electrodes 5 consists of a per forated, tungsten shell ?lled with a mixture of electron emitting materials, such- as a mixture of aluminum oxide, tungsten and an alkaline earth oxide. Said electrodes 5 are heated to an electron 2,135,661 emitting temperature during the operation of the device by the discharge. Said container i has a stem at each end thereof which stem consists of a quartz tube 2, 1, a graded seal 8, 9, I0, H .fused to the end of said tube 2, ‘I and to said current lead 4. The part 8 of said seal 8, 9, Ni, ii fused to said lead 4 con sists of a glass having a coefficient of expan sion approximating that of the tungsten lead 4 and the part II of said graded seal 8, 9, III, II consists of a glass having a coefficient of expan sion approximating that of the quartz tube 2, ‘I. The intermediate parts 9 and ID of the seal have coe?icients of expansion intermediate those of the parts 8 and H. The part ‘I of said tube 2, 1 extends from the endof said container I to a point adjacent the electrode 5 and has an open ing 8 therein which is but slightly larger in di ameter than the current lead 4 extending through 20 said part 1. The part 2 of said tube 2, 1 extends a short distance beyond the end of the container I and has an opening 3 therein having the same diameter as the part 6 of the opening. In the manufacture of the lamp device de scribed above the stem consisting of the tube 2, 1, the seal 8, 9, [8, H, the current lead 4 and the electrode 5 is ?rst fabricated and the end of the container l is then fused to the'tube 2, l. The other steps in the manufacture of the lamp de The advantages of a gaseous electric discharge lamp device having the above structure have been pointed out above. It will be understood, of course, that numerous changes in the form and details of the device illustrated may be made within the scope of the appended claim, for example, the tube 2, ‘I is wholly within the con tainer I when desired. ' What we claim as new and desire to secure 10 by Letters Patent of the United States is:— A gaseous electric discharge device comprising a vitreous container, electrodes and electrode leads sealed therein, a gaseous atmosphere there in, said container having a stem comprising an elongated tube of vitreous material fused thereto, said tube surrounding one or said current leads and extending a substantial distance into said container, the coe?icient of expansion of said tube being‘ approximately equal to that of said container and being di?erent than that of said 20 current lead, the inner diameter of said tube being slightly larger than the diameter of said current lead, the external end of said tube being closed by a graded seal fused thereto and to said current lead, said current lead extending along said tube and projecting beyond the in ternal end thereof, one of said electrodes being mounted on said current lead and adjacent the inner open end of said tube. 30 vice, such as the treatment of the electrodes, ex hausting the container and introducing the start ing gas and the vaporizable material into the container; are then carried out. ' WILHELM HAGEN. WOLFGANG THOURET.