US3376445A - Mounting means for electron discharge electrodes - Google Patents

Description

April 2, 1968 R FRANKLlN ET AL 3,376,445

MOUNTING MEANS FOR ELECTRON DISCHARGE ELECTRODES Filed Sept. 7, 1965 INVENTORS E0552 r F Ham/(4 w Jaw/v J2 Mc'flETA EY 7% mim ATTORNEYS United States Patent Ofiice 3,376,445 Patented Apr. 2, 1968 3,376,445 MOUNTING MEANS FOR ELECTRON DISQHARGE ELECTRODES Robert F. Franklin, Chatham, and John J. McArtney,

Basking Ridge, N..l., assignors to Wagner Electric Corporation, a corporation of Delaware Filed Sept. 7, 1965, Ser. No. 485,276 6 Claims. (Cl. 313-39) ABSTRACT OF THE DKSCLOSURE A cylindrical anode and a plurality of cylindrical dynodes are secured to metal rings at both cylindrical edges. The rings are secured to an upper and lower beryllium disk by brazing to a rnetalized surface on the disks. Leadin wires are connected to the contact surface of the rings and are brought out through holes in the disks.

This invention relates to an electron discharge device which includes two insulator disks as part of the envelope. It has particular reference to one or more insulator disks made of beryllium oxide for supporting the internal electrodes.

The construction of electron discharge devices which pass heavy currents is often difficult because a means must be provided for dissipating the heat generated by the electrodes. Also, the electrodes must be Well insulated from each other, particularly when high voltages are used. Some prior art designs connected the anode through a large metal-to-glass seal and then provided a large radiator connected to the anode for dissipating the heat to the outside atmosphere. This type of discharge device is expensive to make and provides additional insulation problems because the anode and its radiator mustbe maintained at a high positive voltage. The present design employs a beryllium oxide disk both as an insulator support and as a heat radiator. These two functions are possible because the beryllium oxide, when properly sintered, is a good insulator and is also a reasonably good conductor of heat. The construction, as will be explained later, includes the deposition of a plurality of metalized rings on the disk surface. These rings, and supporting members brazed to the rings, form the supports to which the in ternal electrodes may be secured.

One of the objects of this invention is to provide an improved electron discharge device having insulator disk supports. The design avoids one or more of the disadvantages and limitations of prior art arrangements.

Another object of the invention is to provide a means for effectively cooling the internal components of an electron discharge device without the use of added radiators.

Another object of the invention is to insulate the high voltage components within an evacuated envelope.

Another object of the invention is to increase the mechanical stability of discharge devices and make them more rugged.

Another object of the invention is to facilitate the assembly of the components within high powered electron discharge devices, especially those having a large number of elements.

The device comprises an evacuated envelope which generally includes a cathode, an anode, and other electrodes for controlling the passage of electrons between elements. A first insulator disk, made of beryllium oxide, is provided with a plurality of separated metalized films. A second disk, similar to the first, is Supported opposite to the first and the two disks have their outside edges brazed or otherwise secured to a metallic cylinder which forms part of the envelope. A plurality of supports are secured to the films, generally by brazing, and these supports provide the retaining means for securing all the high voltage elements, which may include an anode, a plurality of dynodes, and one or more control electrodes. The outer surfaces of the two disks are in contact with the ambient atmosphere and generally provide all the cooling necessary. Additional radiator fins may be added to the disk surfaces but if these are used they will not be maintained at a high voltage.

For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description taken in connection with the accompanying drawings.

FIG. 1 is a cross sectional view taken along an axis of the tube and shows the internal arrangement of the discharge device and the members which support the electrodes.

FIG. 2 is a partial cross section of an insulator disk to an enlarged scale. This view shows the metal films deposited on the disk.

FIG. 3 is a cross sectional view of the device shown in FIG. 1 and is taken along line 3-3 of that figure.

FIG. 4 is a partial cross sectional view of a supporting ring and an electrode and illustrates an alternate means of securing the electrode to the ring.

FIG. 5 is a partial cross sectional view similar to FIG. 4 but showing still another alternate means for securing the electrodes to their supporting ring.

FIG. 6 is a partial cross sectional view of an electrode and support shown in FIG. 5 and is taken along line 6-6 of that figure.

Referring now to FIGS. 1, 2 and 3, the discharge device cornprises an outer cylindrical metal tube 10 which forms part of the envelope. An upper bracket 11 and a similar lower bracket 12 are welded or otherwise secured to the inside surface of the outer tube 10. These brackets and the tube are preferably made of Kovar because this metal can be readily sealed to beryllium oxide without too much dilficulty. Each bracket 11 and 12 is provided with a turned-over portion 13 which, in the case of bracket 11, supports an upper ceramic disk 14 and, in the case of bracket 12, supports a similar lower disk 15. The upper disk 14 is provided with a central hole 16 for accommodating a tube 17 of hard glass which is welded or otherwise fused to disk 14-. The upper portion of tube 16 is secured to a metal seal-off tube 18 which is used for exhausting, drying, and for pressure sealing. When the device has been exhausted and sealed by pinchingoff at 20, the glass tube 17 and the exhaust tube 18 may be protected by a metal cap 21, secured to disk 14 by two or more machine screws.

The lower disk 15 is also formed with a central hole 22 and a metal cylinder 23 is brazed to its internal surface. A third small insulator disk 24, which may be made of glass, is secured to the inside surface of metal tube 23 and a number of lead-in conductors are secured to disk 24 for supporting a cathode 25, a grid 26, and support rods 27. The cathode 25 may be provided with an internal heater 28 and other grids or control electrodes may be added. It is understood that the cathode and its adjacent electrodes do not have to dissipate too much heat and therefore heat radiation for these components is not a big problem. The usual lead-in conductors 19 may be sealed in disk 24.

The internal surface of both disks 14 and 15 are provided with metal films 30 for providing a base for supporting members 31. An additional film 32 (FIG. 2) is provided on the outside edge of each disk for brazing to brackets 11 and 12. The discharge device shown in FIG. 1 includes an anode 33 and three dynodes 34, the dynodes 34 formed with louvers 29 for generating and 3 collecting secondary electrons. However, any type of electrode may be used instead of the dynodes and anode and their positions may be changed. Lead-in conductors 38 are positioned in holes in the disk 15 and are welded to supports 31. The brazed film between the disk 15 and support 31 provides an efiicient seal.

In order to deposit the films 30 and 32, the following process may be employed. Powdered molybdenum and powdered manganese are mixed with a solution of amyl acetate and cellulose. This mixture is deposited on the disks by any convenient process. It has been found that the silk screen process is convenient and gives the best results but the material may be sprayed on or painted. After drying, the disks are heated in a hydrogen furnace at about 1500 degrees centigrade for ten minutes. The heat drives off the cellulose and leaves only the powdered metal which at this point has been sintered into the ceramic material to a depth of about .010 inch. The films are now plated with either nickel or gold and then the supporting rings 31 are placed on the films 30, generally with the aid of a jig. The supporting rings 31 are then brazed to the films in a hydrogen furnace at about 780 degrees centigrade. As shown in FIGS. 3 and 6, instead of solid rings, spaced segments 31A may be used. These segments reduce the strains which may be encountered because of the unequal expansion and contraction of the support material 31 and the disk material 15. The disks are now ready for assembly to the electrodes 33 and 34, after which brackets 11 and 12 and tube are joined to the disks 14 and 15.

The dynodes 34 may be placed in contact with the support rings 31 and spot welded to the rings 31 or segments 31A. The smallest dynode may be a complete louvered cylinder. The other dynodes and the anode are first formed as a fiat sheet. Then the louvers are formed and the sheet is bent around the supports 31 after which they are spot welded. In order to facilitate the assembly, the innermost support 31B may be made higher than the outer supports (see FIG. 4), each supporting ring being lower than the next inner adjacent one. Such a design facilitates the use of a spot welder or other fastening means.

The design shown in FIG. 4 illustrates an alternate method of fastening the electrodes to the supports. In this view, supports 31B are formed with a bent-over portion 35, extending away from the axis of the tube. The electrode 34 is formed with a turned-over portion 36 and the two bent-over portions 35 and 36 may be easily spot welded to each other by resistance welding or other means.

FIG. 5 shows another alternate method of securing the electrodes 34 to the support rings 31C. This method includes the use of a plurality of machine screws 37 which are threaded into rings or segments 31C. FIG. 6 illustrates the use of an elongated Washer 38 which can be first formed in an are which is less than the curvature of the electrode 34. When the screw 36 is tightened, the washer assumes the same curvature as the electrode and holds it securely in place.

From the above description, it is evident that a new method for manufacturing an insulator disk has been described. The insulator disk conducts heat to an ambient atmosphere without transferring any of the high voltages which may be applied to the internal electrodes for the operation of the discharge device. It is also evident that the above described construction may be employedfor a diode for the rectification of high voltage power supplies. The disks 14 and 15 may take on the formof flattened cones having their outermost electrodes con siderably longer in extent than the electrodes adjacent to the cathode.

The foregoing disclosure and drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense. The only limitations are to be determined from the scope of the appended claims.

We claim:

1. A mounting means for electrodes in an electron discharge device comprising; a first and second insulator disk of sintered berylllum oxide mounted in parallel and concentric relationship, a plurality of flat metal films sintered to said disks on respective opposing faces thereof, a plurality of metal rings concentrically mounted on the disks and brazed to said metal films, a plurality of cylindrical metal electrodes mounted between the first and second disks and secured to the sides of the metal rings, a cylindrical metal film sintered to the edge of both disks, and a solid metal cylinder brazed to said cylindrical films to form a portion of the discharge device envelope, and a lead-in conductor connected to each of said metal rings secured to one of the disks, each of said lead-in conductors passing through a hole in the one disk and secured to the contact surface of a metal ring.

2. A mounting means as claimed in claim 1 wherein said metal electrodes are secured to their respective metal rings by brazing.

3. A mounting means as claimed in claim 1 wherein said metal electrodes are secured to their respective metal rings by machine screws.

4. A mounting means as claimed in claim 1 wherein said metal films are made of a mixture of molybdenum and manganese.

5. A mounting means as claimed in claim 1 wherein said metal rings are separated into a plurality of segments for reducing the strains due to changes in temperature.

6. A mounting means as claimed in claim 1 wherein said metal rings are formed with a bent-over edge for Welding to the edges of the electrodes.

References Cited UNITED STATES PATENTS 1,991,767 2/ 1935 McCullough 313-260 X 2,002,667 5/ 1935 Knoll 313-289 X 3,222,557 12/1965 Meacham et a1. 313-44 JAMES W. LAWRENCE Primary Examiner.

DAVID J. GALVIN, Examiner.

P, C. DEMEO, Assistant Examiner.

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