US2569665A - Electron flow device - Google Patents

Description

Oct. 2, 1951 GQSLING 2,569,665

ELECTRON FLOW DEVICE Filed Nov. 18, 1949 a 32 in H h h M U 24 fine/2202m- (Lsepk 5605/2659 Patented Oct. 2, 1951 ELECTRON FLOW DEVICE Joseph B. Gosling, Milwaukee, Wis., assignor to General Electric Company, a corporation of New York Application November 18, 1949, Serial No. 128,163

6 Claims. 1

The present invention relates in general to electronics, and has more particular reference to electron fiow devices, especially electronic rectifiers, the same comprising improvements and betterments in devices of the sort illustrated and described in United States Letters Patent No. 2,332,428, of October 19, 1943.

An important object of the invention is to provide a new and improved electron flow device, comprising an envelope and embodying novel electrode construction and arrangement allowing simplifications in the construction of the device, including its envelope, and having improved performance and operating characteristics, and at the same time providing a device of small, compact size.

Another important object is to provide a device of the character mentioned having a metal cup adapted to serve both as the anode of the device and as a portion of the enclosing envelope; a further object being to provide means for sealing the metal anode cup directly to glass envelope portions.

Another important object of the invention is to provide a device of the character mentioned having a corrugated envelope portion of glass, with a cup-shaped metal dome, forming a metal envelope portion hermetically sealed to the corrugated glass envelope portion at an end thereof, and a cathode structure supported on the remote end of said glass envelope portion in position in said envelope to present an electron emitting element of said cathode in operative position within said metal dome.

Another important object is to provide an improved, low cost structure through simplification of anode fabrication, including elimination of much of the glass envelope portions, the struc- .ture allowing for the shortening of necessary exhaust schedules in conditioning the device for operation, after fabrication thereof, said improved structure resulting in the elimination of dirt catching crevices at the anode end of the device.

.Another important object is to provide a device of the .character mentioned having improved structural features providing for rapid heat dissipation from the anode to circumambient fluid in which the device may be disposed when in operation, thereby improving the maximum power rating at which the device may safely be operated.

Another important object is to provide an improved structural design for electron flow devices whereby devices embodying the new design may by allowing for the external support, as by chuck-' ing, of the anode during the assembly of the anode and'cathode structures and the attachment thereof on the glass portions of the envelope; a further object being to provide an improved design eliminating the heretofore conventional re-entrant anode seal envelope portion.

Another important object is to provide a device of the class described for operation as a fluid immersed unit for cooling purposes, and adapted for operation at exceedingly low temperature.

The foregoing and numerous other important objects, advantages, and inherent functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings:

Fig. l is a perspective view of an electronic rectifier embodying the present invention; and

Fig. 2 is a sectional view taken longitudinally through the device shown in Fig. 1.

To illustrate the invention, the drawings show an electronic device in the form of a rectifier II, comprising a sealed envelope I2 of suitable material, an anode I3, and a cathode I 4.

The anode I3 comprises a hollow metal shell I5 of preferably cylindrical configuration, closed at one end to form a preferably hemispherical dome I6. Spaced behind its open end IS, the shell I5 is preferably formed with a shoulder II, providing an external seat upon which a sealing skirt I8, preferably of sheet metal, may be snugly seated and sealed, as by welding or brazing with copper, as indicated at I9, circumferentially of the shell.

The sealing skirt I8 preferably comprises metal adapted readily to seal with glass, and forms a sealing rim 20 outwardly of, concentric with respect to, and preferably offset rearwardly of the open end I 6 of the shell I5. The skirt I8, and preferably also the shell I5, may be die formed in a. suitable press and preferably comprise nickel-cobalt steel.

The envelope I2 comprises a glass member 2| of material adapted readily to seal with the rim 26 of the metal skirt. The envelope portion l2 preferably has a medial corrugated portion 22 and an open end comprising a rim 23, sized to form a glass-metal seal with the rim 20 of the sealing skirt i8, whereby the anode shell may be sealingly integrated with the glass envelope portion l2 and form one end of the envelope, with the open end iii of the shell projecting within the open end of the glass envelope portion, beyond the glass-metal seal, to thereby shield the seal against bombardment of electrons emitted by the cathode l4. The inwardly extending bends 22 of the corrugations may have thicker wall section than the remaining portions of the corrugations. These inwardly extending bends are exposed to electronic bombardment to a greater extent than are the outwardly extendin portions of the corrugations. As a consequence, the greater thickness of the portions 22 aifords desirable dielectric strength at the zones of maximumelectrostatic stress.

The dome remote end of the envelope comprises a glass disk 24, formed with a pair of spaced openings 25 in which cathode support stems 26 may be assembled and sealed, as by means of cup-shaped sealing elements 21 of metal adapted to seal readily with glass. These elements 21 may comprise cup-shaped members sealed on the stems 26 outwardly of the envelope to provide annular sealing rims adapted to form glass-metal seals with the glass material of the end wall 24 around the openings 25. The disk 24, stems 26, and the hereinafter more fully described cathode structure l4 may be constructed as an assembly unit and then mounted in the envelope by sealing the edges of the disk 24 to the dome remote end edges of the glass envelope portion 2|, as at 24', whereby the disk 24 becomes an integral end closure wall of the en'- velope.

The stems 26 have portions 28 extending outwardly of the envelope for connecting the cathode with an external power source, the cathode structure l4 being supported on the stems 26 within the envelope. Said cathode structure preferably comprises a pair of mounting stems 29 and 29', each mounted on and electrically connected with a corresponding one of the support stems 26. These mounting stems 29, 29', extend from the stems 26 within the envelope and into the anode shell IS, the stem 29 preferably extending coaxially within the envelope and having sealed enclosing the stem connected ends of the members 29. 29', and forming a shield for protecting the same and the glass-metal seals of the stems 26 against stray electron bombardment. To this end, the shell 30 may be sealed on and electrically connected with the stem 29, as by welding it to a metal support sleeve 3| on the member 29. The member 39 may comprise nickel or steel. The support stem 29' may be disposed in parallel spaced relationship with respect to the stem 29, and may extend through a suitable opening formed in the skirt 39, said member 29' being insulated from said skirt, as by means of a suitable insulating sleeve 32. The upper end 33 of the stem 29' is bent and disposed in coaxial spaced relationship with respect to the upper end of the stem 29.

The cathode structure preferably comprises an electron emitting filament 34 supported on the stems 29, 29', in position coaxially within the anode shell. To this end, the opposite ends of the filament 34 are electrically connected, respective- 4 1y, with the spaced apart facing ends of the stems 29, 29'. The portions of the stem 29' adjacent its filament connected end 33 are also preferably formed as a loop or loops 35 about the electron emitting filament 34.

In order to insure against damage or destruction of the emission element 34 as the result of inverse electrical discharge or flash-over from the anode to the emission element, flash arresting means maybe provided in the form of a sheet metal disk 36, preferably comprising nickel, mounted on and electrically connected with the stem 29, as by welding it to a metal mounting collar 31 on the stem 29. The stem 29' may extend in an opening formed in the disk, outwardly of the collar 31, and the stem 29' may be insulated from the disk, as by means of an insulating collar 38; In order to improve its function, the peripheral edges of the disk may be curled to semi-circular sectional configuration, to form a flash receiving edge head 39 at the peripheral edge of the disk.

It should be understood, of course, that an electron flow device of the character here considered functions as the result of flow of electrons emitted by the cathode element, which travel to and impinge upon the anode. When the device comprises a rectifier, the stream of electrons passing between the cathode and anode form a conduction path, along which electrical current may flow in one direction only, so that such uni-directional flow phenomena may be utilized for the purpose of rectifying or converting alternating or fluctuating electrical energy to produce uni-directional electrical power.

For efficient operation, the atmosphere within the envelope should be maintained at low pressures of the order of 0.02 micron of mercury, and the maintenance of low pressure conditions is of particular importance, since the operation of an electron flow device will result in the ionization of any gas particles within the envelope and with which an electron may collide during its travel between cathode and anode. Such a collision r results in the production of a positively charged ion, which may impinge upon the cathode element and dislodge therefrom a particle of its constituent material. In order, therefore, to preserve the emission element for long service life, among other things, it is desirable to eliminate, as far as possible, all gaseous matter from within the envelope. To this end, the envelope is thoroughly evacuated as a part of the manufacture of the device, evacuation being accomplished after the constituent parts of the device have been assembled and sealed in the envelope. During the evacuation of the envelope, the device and all of its operating parts are strongly heated in order to remove all impurities, including such gases as may be occluded in the anode, cathode, and envelope walls.

The end wall 24 of the glass envelope portion may be pre-formed with a central opening 40.for connection, as by means of a suitable glass tube, with an exhaust pump, in order that the device after assembly may be conditioned for operation by procedures including the evacuation of the sealed envelope. ,The envelope may be finally sealed at the conclusion of the conditioning process, in evacuated condition, by sealing oif the glass exhaust pump connection to form an integral sealing bead 4| at the opening 40, whereupon the device will be ready for service.

The device may be energized for operation by connecting the stem ends 28 with a suitable source of cathode energizing power to promote electron flow from the emitter 34. The anode dome may be provided with a terminal stud 42 and clamp nut 43, forming means for electrically connecting the same with a suitable conductor forming a part of a rectifying circuit, which may also be connected with one of the stem ends 28.

It will be seen from the foregoing that the device of the present invention represents substantial simplification as compared with devices of the sort heretofore provided, as exemplified in United States Letters Patent No. 2,332,428. Not only have the expensive and relatively diflicultly scalable re-entrant end portions of the glass envelope been eliminated, thereby greatly simplifying the glass-metal envelope sealing operations, but the over-all length of the device required for any selected power rating has been very substantially diminished, to thereby reduce the overall space required for apparatus comprising several rectifier devices forming a rectifying system. Rectifying systems, embodying rectifiers made in accordance with the teachings of the present invention, may thus be housed in substantially smaller casings than heretofore required for systems of equivalent power rating comprising units of the sort heretofore available. 1

Devices embodying the present invention, moreover, can be manufactured at cost substantially lower than has heretofore-been possible, due to the simplification of the anode itself, the elimination of much envelope glass, and the arrangement of the glass-metal seal at 20 in an externally accessible position, thereby greatly facilitating the sealing operation, a further advantage residing in simplification of the sealing skirt l8 and its attachment on the anode element by circumferential welding or brazing.

The structure and arrangement of the present device also allows greater accuracy and uniformity in the finished device, since the anode element may be positively supported, as in a suitable chuck, and held in exact position with respect to the cathode structure during assembly and sealing of the anode element with the glass envelope portions, thereby assuring exact alinement of the filament 34 within the anode, in the flnished structure. This circumstance allows for the production of devices embodying the present invention on semi-automatic machines, thereby reducing production costs, the elimination of reentrant envelope seal portions contributing to this desirable result.

Electron flow devices of the sort herein disclosed are commonly operated in position immersed in insulating and cooling fluid, such as oil, to which heat, generated as a result of the operation of the device, is dissipated. Devices embodying the structure of the present invention provide immeasurably better heat transference to the circumambient cooling fluid. As a consequence, the devices of the present invention are adapted to operate at relatively low temperature as compared with comparable devices of the sort heretofore known. Consequently, devices enibodying the present invention may be given higher current ratings, and may thus safely perform substantially more work than comparable devices of equivalent physical size heretofore available.

newsmall devices of the present invention operate at very much lower oil-metal interface temperature, because of the substantially greater heat dissipating area of the anode in contact with the circumambient cooling fluid. Where the operating temperature of the anode in devices heretofore available has been of the order of 200 C., the operating'anode temperature in devices embodying the present invention is of the order of 0., thereby minimizing the possibility of deterioration of the circumambient oil in which the devices are immersed for operation.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing descriptions, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or' scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. An electron flow device comprising a sealed envelope embodying a glass envelope portion and a. metal shell sealed in end-to-end relationship to form the opposite end portions of the envelope, said glass portion and shell having matching seal rims forming a circumferential glass-metal seal medially of the opposite ends of said envelope, said glass portion being formed with circumferential corrugations between the ends thereof and tapering inwardly from its shell sealed end toward the opposite end thereof, and a cathode structure mounted within said envelope on said glass portion and supporting an electron emitting element within said metal shell to constitute the same as an anode adapted to dissipate heat therefrom directly outwardly of said envelope.

2. An electron flow device comprising a sealed envelope embodying a glass envelope portion and a metal shell sealed in end-to-end relationship to form the opposite, end portions of the envelope, said glass portion and shell having matching seal rims forming a circumferential glassmetal seal medially of the opposite ends of said envelope, said glass portion being formed, between the ends thereof, with circumferential corrugations comprising alternate inwardly and outwardly extending bends, said inwardly extending bends having greater sectional thickness than said outwardly extending bends, and a cathode structure mounted within said envelope on said glass portion and supporting an-electron emitting element within said metal shell to constitute the same as an anode adapted to dissipate heat therefrom directly outwardly of said envelope.

-3. An electron fiow device comprising a sealed envelope embodying a glass envelope portion and a metal shell sealed in end-to-end relationship to form the opposite end portions of the envelope, said glass portion and shell having matching seal rims forming a circumferential glassmetal seal medially of the opposite ends of said envelope, said glass portion being formed, be

said outwardly extending bends, said glass por-' tion tapering inwardly from its shell connected end toward the remote end thereof, and a cathode structure mounted within. said envelope on said glass portion at said shell remote end thereof, and supporting an electron emitting element within said metal shell to constitute the same as an anode adapted to dissipate heat therefrom directly outwardly of said envelope.

4. An electron flow device comprising a sealed envelope embodying a pair of cup-shaped envelope portions, respectively formed of glass and of metal, and having open ends circumferentially sealed together to form a composite envelope of glass at one end and of metal at the other, and a cathode structure mounted within said envelopgon the bottom of the glass member in position supporting an electron emitting element within the metal member to constitute the same an an anode, said glass member having side walls extending between the opposite ends thereof and formed with circumferential corrugations com- 1 from said sealed end, said side walls being formed with circumferential corrugations embodying alternate inwardly and outwardly extending bends, said inwardly extending bends having greater sectional thickness than the remaining portions of said side walls, and a cathode structure mounted on said bottom wall and having portions extending within said metal shell, said cathode structure including an electron emitting element supported within and centered upon the longitudinal axis of said metal shell, whereby to constitute the same as the anode of said rectifier.

6. An electronic rectifier comprising a sealed envelope embodying a glass portion and a metal shell sealed in end-to-end relationship, said glass portion and shell having matching seal rims forming a circumferential glass-metal seal medially of the'opposite ends of said envelope, said glass portion being formed with circumferential corrugations between the ends thereof and tapering inwardly from its shell-sealed end toward the opposite end thereof, and a cathode structure mounted within said envelope on said glass portion and supporting an electron emitting element within said metal shell whereby to constitute the same as an anode adapted to dissipate heat therefrom directly outwardly of said envelope.

JOSEPH B. GOSLING.

' REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,933,329 Hull Oct. 31, 1933 2,385,435 Werner et a1 Sept. 25, 1945 Atlee et al July 26, 1949

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