US3392296A - Electron multiplier amplifier discharge device - Google Patents

Description

July 9, 1968 R. F. FRANKLIN ELECTRON MULTIPLIER AMPLIFIER DISCHARGE DEVICE 2 Sheets-Sheet 1 Filed Aug.

' 3,392,296 ELECTRON MULTIPLIER AMPLIFIER I DISCHARGE DEVICE Robert F. Franklin, Chatham, N.J., assignor to Wagner Electric Corporation, a corporation of Delaware Filed Aug. 27, 1965, Ser. No. 483,118 12 Claims. (Cl. 313-44) This invention relates to an electron discharge device containing a plurality of dynodes in addition to the usual anode, cathode and control electrodes. The invention has particular reference to a discharge device which contains a plurality of cooling fins, at least one for each dynode, for cooling the electrodes within the discharge envelope and for forming a part of the envelope wall.

The electron discharge device described herein includes a central cathode, one or more control electrodes, a plurality'of louvered dynodes, and an anode, all grouped in spaced relation about a common axis. This form of multiplier amplifier is old in the art and has been described in books and other publications. The present invention comprises an improvement on prior art designs wherein a plurality of cooling fins extend above and below the discharge space, these fins each including a pair of adjoining cylindrical members which are joined or near their extremities afterthe discharge components have been positioned. This design not only provides excellent cooling of the discharge components but also permits much easier assembly. The fins may also be used to make contact with a socket for connection to an external circuit.

Throughoutthe specification and claims, the term dynode denotes a series of intermediate electrodes, generally spaced between a cathode and an anode, and given a potential more positive than the cathode. The electrons from the cathode strike an adjacent dynode and generate secondary electrons which are passed on to other dynodes.

One of the objects of this invention is to provide an improved electron discharge device whichavoids one or more of the disadvantages and limitations of prior art devices.

Another object of the invention is to reduce the assembly time of a discharge device having a plurality of concentric components. 7

Another object of the invention is to increase the accuracy of the placement of component parts in an electron discharge device.

Another object of the invention is to increase the dis sipation of heat generated by the components in a multiple component dis-charge device.

Another object of the invention is to provide a large contact area for each of the discharge device components so that connection can be easily made to anexternal circuit.

Theinventioncomprises an electron discharge device having a sealed envelope containing a cathode for the emission of electrons and an anode for collecting emitted electrons. A plurality of cylindrical secondary emission dynodes are mounted between the anode and cathode and in axial alignment with them. Each dynode is formed with angular louvered portions which are disposed in slots formed in the dynode sheet. Each dynode and the anode are secured to a plurality of insulator rings for holding the discharge components in position. Each of the components is also connected to a metal cooling fin which extends beyond the interior envelope space.

One of the features of the invention includes the formation of each cooling fin by combining two adjacent metal cylinders which are welded together at their extremities.

Another feature of the invention includes the use of United States Patent ice insulator rings made of ceramic material and metalized by the deposition of a molybdenum alloy on two of its sides. The components and cooling fins are brazed to this metalized film.

Another feature of the invention includes a louvered anode and a solid dynode positioned on the outside of the anode.

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 perspective view of the discharge device with a portion cut away to show the internal structure;

FIG. 2 is a top view of the discharge device;

FIG. 3 is a partial cross sectional view, to an enlarged scale, showing one of the dynodes and a cooling fin prior to welding its upper edge;

FIG. 4 is a cross sectional view of the discharge device shown in FIG. 1 and is taken along a horizontal plane which bisects the device. This view shows the internal structure of the device and the angular disposition of the louvers; and

FIG. 5 is a schematic diagram of connections showing how the discharge device may be connected as a high-gain amplifier. In this diagram three control electrodes are employed and the device is connected for positive pulse amplification.

Referring now to the drawings, the discharge device 10 includes an outer envelope shell 11, a cathode 12, and a plurality of ceramic insulator rings 13 which generally form an upper and lower wall defining the discharge space within the envelope. Between each of the adjacent rings 13 is a cooling fin 14, formed by two metal sheets which may be close fitting over their entire extent. As shown in FIG. 3, the base of one sheet 14-1 includes a turned-over portion 15 which is in contact with the lower face of an insulator ring 13. The base of the adjoining sheet 14-2 includes a turned-over portion 16 which is joined to the lower face of the adjacent ring. The turned-over portion 16 supports a metal ring 17 and a dynode 18 which is formed with louvers 20. The lower ends of the dynodes 18 are secured in a similar manner to turned-over portions of the lower cooling fins 21 and to metal rings 22, similar in construction to the upper rings 17.

While it is convenient to weld the upper and lower extremities of sheets 14, it is obvious that a metal weld may be made at an intermediate position such as indicated by arrow 23. Such a weld may be made by two compression rollers mounted on arms (not shown) which may extend into the spaces between the cooling fins. The invention does not depend upon a Weld or soldered joint at the extreme upper and lower ends of the cooling fins.

The cathode 12 is shown mounted in the axial position of the device. The construction, above described, may be used as a diode, and in such a case there will be no control grids surrounding the cathode. FIG. 1 shows an inner grid 23 and an outer grid 24 which may be used in various circuits for the control of amplifier output currents. Other control electrodes may be added. The invention does not depend upon the number of control elements used.

When this discharge device is first assembled and all the components have been secured in. place, the device may be exhausted by connecting a vacuum pump to an exhaust tube 25 which is sealed into the central portion of the upper central ceramic disk. After the exhaust processes and the final pumping cycle, the exhaust tube 25 is pinched off making a pinched seal 26. This seal is then protected by a hollow cylindrical cap 27 which may be attached to the central structure by a plurality of screws 28.

The composite upper disk formed by rings 13 and the lower disk formed by similar ceramic rings is secured to the outer portion of the envelope 11 by an upper bracket 30 and a lower bracket 31. These brackets are secured to the outer envelope wall 11 at the edges 30A and 31A. The brackets 30 and 31 are brazed to the rings by the use of the usual metallic film deposited upon the ceramic rings 13. These two brackets are for assembly convenience only and any other type of fastener means may be used.

The cross sectional view shown in FIG. 4 illustrates one preferred form of the invention. The cathode 12 and the two control electrodes 23 and 24 are shown in abbreviated form because they form no part of the improvements which constitute the invention. The first, second, third and fourth dynodes 18 are formed with louvers 20 which have been punched from the dynode sheet and bent into an angle which is substantially 45 degrees from the tangent of the dynode sheet at that point. It should be noted that the louvers 20 are staggered, that is, the louver extensions 20 extend clockwise in the first dynode and counter-clockwise in the second dynode. This design helps to increase the generation of secondary electrons but any other type of louver or louver angle may be used.

The anode 32 in this design is positioned between the last two dynodes and it contains a plurality of louvered portions 32 which are bent so that they make an angle of substantially 90 degrees with the tangent of the anode sheet. The last dynode 33 is solid, having no slots nor perforations, and, as shown, is on the outside of anode 32. It has been found that this arrangement of electrodes produces more load current and a greater amplifier gain than if the anode were solid and positioned on the outside of all the dynodes.

The diagram of connections shown in FIG. is one example of the circuit which may be used with this device. The cathode 12 employes an internal heater 34 and there are three control electrodes 23 and 24. The main power supply 35 is a 1,900 volt direct current supply and is bridged across six neon discharge tubes 36, each arranged for the voltage shown in the figure. Resistors may be used instead of the neon diodes. The discharge tubes 36 may be replaced by Zener diodes or any other type of voltage regulating means may be used. An additional power supply 37 is connected between the anode 32 and the outside dynode 33. This dynode also generates secondary electrons, some of which are collected by the anode. The load 38 is connected in series with the anode 32 and the direct current supply 35.

The first control electrode 23 is biased by a battery 40 to volts below the cathode potential and is connected in series with a resistor 41 which in this case is 40,000 ohms. Input terminals 42 are connected to the cathode 12 and the first control electrode 23 in series with a blocking capacitor 43. When a short positive pulse of volts is applied to input terminals 42, an anode current of 5 amperes flows through the 250 ohm load resistor 38.

Insulator rings 13 may be made of any suitable material but it has been found that a ceramic composed of powdered aluminum oxide, when pressed and sintered, forms the best insulating material. These rings are then covered with a slurry of powdered molybdenum and manganese mixed with amyl acetate and powdered cellulose. After drying and heating in a hydrogen furnace at about 1,500 C. for ten minutes, the metal film is plated with either nickel or gold. This film forms a substantial base for brazing with any type of metal electrode.

It should be noted that the extremities of fins 14 may be joined by any well-known process, such as welding, soldering or brazing.

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.

I claim:

1. An electron discharge device comprising, a sealed envelope containing a cathode for the emission of electrons and an anode for collecting emitted electrons, a plurality of cylindrical secondary emission dynodes made of conductive sheet and mounted in axial alignment with the cathode, said dynodes including angular louvered portions disposed adjoining slots formed in the dynode sheet for the generation of secondary electrons when bombarded by other electrons under the influence of an electric field, a plurality of insulator rings secured tothe ends of said dynodes for holding the dynodes in position, and a plurality of metal cooling fins secured to said insulator rings and to the ends of the dynodes, said fins forming spacers between the insulator rings and extending away from the interior envelope space.

2. An electron discharge device comprising, a sealed envelope containing a cylindrical cathode for the emission of electrons and an anode for collecting emitted electrons, a plurality of cylindrical secondary emission dynodes made of conductive sheet and mounted in axial alignment with the cathode, said dynodes including angular louvered portions disposed adjoining slots formed in the dynode sheet for the generation of secondary electrons when bombarded by other electrons under the influence of an electric field, a plurality of insulator rings secured to the ends of said dynodes for holding the dynodes in position, and a plurality of metal cooling fins secured to said insulator rings and to the ends of the dynodes, said fins forming spacers between the insulator rings, each of said fins including a pair of cylindrical sheets joined at their outer extremeties and forming a part of the envelope.

3. An electron discharge device as claimed in claim 2 wherein said envelope also includes a control electrode mounted adjacent to the cathode surface for altering the electric field adjoining the cathode.

4. An electron discharge device 'as claimed in claim 2 wherein said envelope also includes a cylindrical anode sheet and a cooling fin joined to the anode edge.

5. An electron discharge device as claimed in claim 4 wherein said anode is formed. with louvered portions disposed adjoining slots formed in the anode sheet.

6. An electron discharge device as claimed in claim 5 wherein said anode louvered portions are disposed at substantially right angles to the anode sheet and wherein said slots are formed parallel to the cylindrical axis.

7. An electron discharge device comprising, a sealed envelope containing a cathode for the emission of electrons and a cylindrical anode for collecting emitted electrons, a plurality of cylindrical secondary emission dynodes mounted in axial alignment with the cathode and the anode, said dynodes including angular louvered portions disposed adjoining slots formed in the dynodes for the generation of secondary electrons, said dynodes positioned between the cathode and anode in spaced relation, a plurality of insulator rings secured to the ends of said dynodes and said anode for holding the dynodes and anode in position, a plurality of metal cooling fins respectively secured to each insulator ring and to the ends of each dynode and anode, said fins each including a pair of adjoining cylindrical sheets joined adjacent to their outer extremities and forming a part of the envelope.

8. An electron discharge device as claimed in claim 7 wherein said insulator rings are made of ceramic and are metalized on two sides prior to assembly by the deposition of a molybdenum alloy.

9. An electron discharge device as claimed in claim 7 wherein said insulator rings and said cooling fins are secured respectively to both ends of the dynodes and the anode.

10. An electron discharge device as claimed in claim 5 7 wherein said dynodes are secured to said insulator rings by brazing to a metalized surface film on the rings. 11. An electron discharge device as claimed in claim 7 wherein an additional solid dyno'de is positioned around the anode on the anode side away from the 5 cathode and wherein said anode is formed with louvered portions adjoining slots in the anode.

12. An electron discharge device as claimed in claim 7 wherein the outer edges of said cooling fins are joined by welding.

References Cited UNITED STATES PATENTS 1,683,134 9/1928 Hull 313-105 X 2,189,318 2/ 1940 Krenzien 313-105 2,246,172 6/ 1941 Hergenrother 313-105 JOHN W. HUCKERT, Primary Examiner.

10 R. F. POLISSACK, Assistant Examiner.

Claims (1)

1. AN ELECTRON DISCHARGE DEVICE COMPRISING, A SEALED ENVELOPE CONTAINING A CATHODE FOR THE EMISSION OF ELECTRONS AND AN ANODE FOR COLLECTING EMITTED ELECTRONS, A PLURALITY OF CYLINDRICAL SECONDARY EMISSION DYNODES MADE OF CONDUCTIVE SHEET AND MOUNTED IN AXIAL ALIGNMENT WITH THE CATHODE, SAID DYNODES INCLUDING ANGULAR LOUVERED PORTIONS DISPOSED ADJOINING SLOTS FORMED IN THE DYNODE SHEET FOR THE GENERATION OF SECONDARY ELECTRONS WHEN BOMBARDED BY OTHER ELECTRONS UNDER THE INFLUENCE OF AN ELECTRIC FIELD, A PLURALITY OF INSULATOR RINGS SECURED TO THE ENDS OF SAID DYNODES FOR HOLDING THE DYNODES IN POSITION,

Images