US1432867A - Electron-discharge device and method of making the same - Google Patents

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M. J. KELLY. ELECTRON DISCHARGE DEVICE AND METHOD OF MAKING THE SAME.

APPLICATION FILED NOV. I5 I919.

Patented; Oct 24!, 1922.

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MERVIN a. KELLY, OF NEW YORK, n. Y.,"ASSIG1\TOR T WESTERN ELECTRIC COMPANY, INCORPORATED, ormpw YORK, 1\T.'Y., A CORPORATION or NEW YORK.

ELECTRON-DISCHARGE DEVICE AN D METHOl OF MAKING THE SAME.

' Application filed Noveniber 15, 1919. Serial No. 338,213.

To all whom it may concern. 1

Be it known that I, MERVIN KELLY,

a citizen of the United States, residing at New York, in the county of Bronx, State 5 of New York, have invented certain new and useful Improvements in Electron-Discharge Devices and Methods of Making the Same, of which the following is a full, clear, concise, and exact description.

This invention relates to electron discharge devices and toa method of manufacturing them.

One object of the invention is'to increase the amount ofpower which may be applied '15 to an electron discharge device while still keeping within the safe limits of'temperature under which the electrodes can func- 'tion. I

Another object is the elimination of the objectionable efi'ect which is sometimes produced in electron discharge devices, namely blocking, which is caused partly, at least, by undesirable secondary em1ssion from the the rovision of a black coatin on the electrodes of electron discharge evices, particularly the plate and grid. In a preferred form of my invention using electrodes comis produced on the surface by oxidation at a suitable temperature, preferably about.

900 C. in an electric furnace in the presence of air. jjUSlllg other metals for elec trodes, such as molybdenum, other suitable black coatings may be formed within the spirit of my invention. I Electron discharge devices'have'been- 'de ficient in their operation in one respect because only alimited amount'ofi wer could be handled by them without eating, the

electrodes beyond a safe temperature. By;

increasing the capacity of the electrodes to radiate heat faster, we can increase the power applied an'dsti-ll keep the temperature within safe limits. p

Furthermore, electron discharge devices, particularly when considerable amounts of power are handled, have been subject to a @5 blocking phenomenon which has paralyzed Still another object is to eliminate the posed of nickel, a coating of oxide of nickel "21 and 22.

' the tube operation. When strong electron currents are passing, the bombardment of the grid sometimes roduces a secondary emission from they grid, the flow of which secondary current is opposed in direction to the normal operating electron or space current. In some cases, this secondary current has completely neutralized the normal current, and thus blocked the proper functioning of the device.

- A second feature of my invention involves the coating of the grid or control electrode with a substance which acts to substantiall eliminate electron emission therefrom.- t has been found that nickel oxide, or molybdenum oxide on the grid surface produce this result. Other substances which are semi-insulating in their properties may be used. It is not here necessary to develop the theory as to why such a coating on the grid reduces the electron emission therefrom and is suflicient to state that these coatings do so reduce it.

My invention is illustrated in the drawing which shows a form of device to which my invention is. applied.

As illustrated, the device. involving my. invention comprises a preferably evacuated bulb 10 to which the usual base portion 11 i's'attached. This base portion provides a support for suitable terminals 12. With in the bulb 10 is a stem portion 13 from which an arbor or post 14-.arises. This arbor 14 provides means for supporting an anode 15, a grid 16 and a filament 17. The anode as shown is in the form of a hollow cylin= der having an oval cross section and is supported by suitable wires extending from post 14, these wires not being shown. The anode 15 surrounds the grid 16 and the filamentli. The grid 16 is supported from the arbor 14 by means of wires, such as 18, and the filament 17. is supported from the arbor 14 by means of wires 19 connected to the top of the filament. The filament is supported at its bottom by means of w1res 20, The wires 20 and 22 also serve as lead-in wires for the current apphed to the filament. Wires '23 and 24 are lead-in wires connecting respectively to the plateand the grid. While I have described the mechanical arrangement-of the electrodes tube to which my invention is applicable.

for the purpose of illustrating one form of In the manufacture and preparation of the electrodes for assembly within the tube, the plate 15 and the grid 16, which arev 1n the form shown, of nickel, are preferably subjected for a suitable'time in an'electric furnace to a temperature of-about 900 0., in the presence of air or oxygen. This treatmerit. produces on the surfaces of these elec trodes a coating of black nickel oxide. This 1. coating, possessing as it does the characteristics of a black body radiator, provides a means whereby the electrodes more efficiently'radiate heat so that greater amounts of power can be supplied to them .at a. given temperature of operation; p

In the case of the coating applied to the control or grid electrode 16, it is foundthat secondary emission from the grid is' practically eliminated and that thermionic emission from the grid, due to the presence thereon of particles of coating from the fila ment, is likewise substantially reduced. H

In some cases, particularly where the 'device is to be used for a detector of minute currents or as adetector oramplifier which operates intermittently, it is found that the device will operate more efficiently if, the coating is removed from the surface of the plate which .lies in the path of the electron stream. The coating may be removed in any su1table manner and a preferred method of .so removing the coating comprises the sub jection of this face to the action of a jet of hydrogen or other reducingagent While the face is heated. Another method of. re-

movin the coating is to subject the elec trode; ace to the action of a' blast of abrasive material which efficiently removes the 1. The method of manufacturing electron discharge devices which comprises producing I a black. coating on the surfaces of an elecfrom one of said surfaces.

2. The method of manufacturing electron discharge devices which comprises produc- 111g a black" coating on the surfaces of an electrode and then removing the coating trode and then removing the-black coating ,from one of said surfaces by means of a reducin agent.

3. he method of manufacturing electron discharge devices which comprises producing a black oxide coating on the surfaces of an electrode and thanv removing the coating ing a coating on the surfaces of an electrode spaced apart from one of said surfaces by means of reducing agent.

' 4h The method of manufacturing electron discharge devices which comprises producby means of subjecting itto high temperature in the presence of air and then removing the coating from one of said surfaces by means of a reducing agent.

5. The method of manufacturing electron discharge devices which' comprises producing a coating on the surfaces of an electrode by means of subjecting it to high temperature in the presence of ai and then" removing the coating from one of said surfaces by means of a blast of abrasive material.

6. An electron discharge deyice comprising a cathode, an anode and a grid electrode,

said grid electrode being interposed between said cathode and anode, and a coating for said grid electrode capable of substantially eliminating electron emission therefrom.

7. An electron discharge device compris-v ing a cathode, an anode, and agrid electrode, said grid electrode being interposed between said cathode and anode, and a semi-insulating coating for said grid electrode capable of substantially eliminating electron emission therefrom. I

8. An electron discharge device comprising a cathode and anode, said anode having one side lying outside the path of electron current, and a black coating for that side of said electrode.

9. An electron discharge device comprising a cathode and an anode, and a black coating on said anode.

10. An electron discharge device comprising a cathode and a control electrode spaced .apart from said cathode, and a black coating on 'said control electrode.

11'. An electron discharge device comprisin a cathode, anode and control electrode, said control electrode and said cathode bein spaced apart and a black coating on sald anode and control electrode. I

-12. 'An 'electrondischar e device comprising a cathode and an aim c, said' anode having a,surface' faced away from said cathode and a black coating for that surface of said anode;

' 13. An electron discharge device comprising a cathode, anode and control electrode, sa d control electrode and said cathode being spaced. apart, a black coatingfor said control electrode anda black coating for all parts of the anode which do not lie in the path of'the electron current.

14. An electron dischar e device comprising a cathode a control e from said cathode, and a coat-. ing of nickel oxide on said control electrode.

15, iAn'electron discharge device comprising a cathode, an anode of nickel and a coatin; r nickel oxide on said an de ectrode of m'ckelv 16. An electron discharge device comprising a cathode, an anode of nickel and a control electrode of nickel, and a coating of nickel oxide for said anode and said control electrode.

17. An electron discharge device comprising a cathode, a grid electrode surrounding said cathode and spaced apart from the same, and a black coating for said grid electrode.

18. An electron discharge device comprising a cathode, a grid electrode surrounding said cathode, an anode surrounding said cathode and said grid electrode, and a black coating on said anode and grid electrode.

19. An electron discharge device comprising a cathode, a control electrode surrounding said cathode, an anode surrounding said control electrode and said cathode, a black coating for said control electrode and for the side. of the anode facing away from the cathode.

20. An electron discharge device comprising a cathode, a control electrode surrounding said cathode, an anode of nickel surrounding said control electrode and said cathode, and a coating of nickel oxide for said control electrode and said anode.

21. An electron discharge device. comprising a cathode, a control electrode of nickel surrounding said cathode, an anode of nickel surrounding said control electrode and said cathode, and a coating of nickel oxide for said control electrode and for that part of the anode which faces away from the cathode.

22. An amplifier comprising a cathode and anode, and a coating having good heat radiating qualities on said anode.

23. An electron discharge device comprising cathode, anode and control electrodes, said control electrode and said cathode being spaced apart, and a secondary electron suppressing coating on said control electrode.

24. An electron discharge device comprising a. cathode, an anode and a' control electrode, said control electrode and said cathode being spaced apart, a secondary electron suppressing coating on said control electrode, and a heat radiating coating on said anode.

In witness whereof, I hereunto subscribe my name this 11th day of November, A. D.

MERVIN J. KELLY.

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