US2283896A - Cathode structure - Google Patents

Description

May 19, 1942.

I. E. MOUROMTSEFF ETAL 'CAIHODE STRUCTURE Fild June 24, 1941 M D lV/V/C/C mum TTORNEY Patented May 19, 1942 Pennsylvania op pany, East Pittsburgh, Pa., a corporation of Application Jiine 24, 1941, Serial No. 299,454

claims. (01. 250- 275) This application is a continuation-inqitit of our copending application Serial No. 360,367, filed V ctober 9; 1940; for Ultra-high frequency oscillator.-

' applicable to other forms of discharge device having similar requirements.

1 1mg. 2 we have illustrated a referred cinbodimeht of our cathode. This cathode com- The inventioii relates'to cathodes andpar'ticu- 5 prises a metal ribbon which may 56 hickli larly todi-rectly heated cathodes. thoriated tungst n, plain tungsten or a nickel- An object of our invention is' to provide a cobalt-titanium alloy sold under the trade-name cathogethavitng no magnetic field or a very weakofionalg f m f th k f 5 one a is ac ive surface. is ri on" is pre era y o a ic ness o 7 Another object of our invention is to provide a 10 to 10 'r' i3is'. tThe cfclngrall' porgion cifn this ifibbofi cathode which will produce a plane wave of is forme in o a a pane ace w ic wi electrons. be the electron-emitting portion of the cathode.

Another object of the invention is to provide 011 p' a ea in t s od ficat 0f Dhakth ch is p e f withstanding vin'g this plane face Ill the electron emitting por 7 potential differences of the order of thousands tion is to provid a p u a y of ldl a 5f Y'olts kfitweeii iis eiwn potential and the potenb i (g l fage-t liese slcts ay be oi any iasof 0 er sec to es; 7 e nui'n er aii size, 1.1 rom e mm 0 e ciency Another object of our invention isto provide We prefer to limit the material removed from a cathode of sturdy construction in which the thisactive area by hose slots to a ut 0% o active electron-emitting portionis confined to a is -t Pfi zg l f' ti 213 5 91 xteld R; desired plane of the cathode. S an la y e 'eng 0 e Op D 95118 Other objects and advantages of the invendivides said face. into a plura y K583341191 tion will be apparent from the following descripspa ed st' ps I2 all i a d p a a d a 1 t a1 tion and drawing in which: W with common end folds I3, is at opposite ends Fig. 1' is a view in cross section through a porof said strips. tlOIl of abd scharge devic t whlch our mventhBecariliszhoff the Irneduced dciggssslectiona-l are? tion has een applied. 7 rolls 6 a 7 Cau 'y e emova' o Fj g 2 a perspective View of t cathode f the material, the intermediate strips l2 between 1, i, the slots will be heated to a temperature greater fication of the cathode of Fig. 2. v V a V v 4 a medication; i, l c N in our copending application Serial No. 360,367; 99 'fi af n the Plane scurfacev S f e l filed @ctober 9, 1940; for Ultra hi'gh frequency; ggg gygg 2:5 ??.sfi ig igg gfifg ip ig' W desired, Pre i l lP and It are bent mm a rear face sit tatea in a V to be apphd e .P P. lit X i i 939. 9 a common pla'il slightly spaced from and aranei hollow body resonator enclosed in a high vacuum with: the fibht fa m 7 3 3 g i f i fi fiig me f? of 40 The ends I! and I8 of the ribbon are bent ca 1 i erelce w away at right angle from the plane formed by e Vanous e ec r0 18 81' of houthe two portions I5 and it, which have aspace sands. The present invention 13 the result of 9 therebetween to prevent any sparking attemPts to find cathofie that would more tween the two faces I! and I8. These ends l1 satisfactorily meet the exacting requirements of and [3 of the ribbon are attached as by Welding a m our Oscluatorto two sturdy standards l9 and 20.

While indirectly heated oxide coated cathodes In Operation aeurrent f r example passes would supply the copious supply of elec o up the standard H! as indicated by the arrow to sired, these oxide coated cathodes necessitated th face I] and then passes outward, in the rear a complicated structure including relatively large plane in conductive rear portion l5, thence ceramic insulators which are difficult to out-gas through the curved face or fold l3, and then to the required degree of perfection required by across the more resistive face Ill to the left to our device. We, accordingly, devised the present the other curved face or fold l4. During this directly heated cathode for our hollow body passage across the face I 0, the current heats up resonator device and this cathode is, of course,

this active 'face to a temperature above that of the rest of the ribbon, because of the reduced cross section.

A copious supply of electrons is emitted in plane waves from the surface of this face In. The current then passes around the curved face or fold l4 and thence in a direction to the right through the conductive rear face l6, parallel with the front face I0, and then through the end I8 of the ribbon and out through the standard 20, as indicated by the arrow associated therewith.

It will be noted that the direction of the current, as indicated by the arrows, in the front face I is opposite to the direction of the current in the rear faces l and 16 parallel to and slightly spaced from this front face 10.

The magnetic field from the current in the front face ID will be substantially neutralized by the magnetic field from the oppositely flowing current in the rear faces l5 and I6, and it will have little or no effect on the electron flow caused by the magnetic field of the heating current.

The cathode is self-supporting and the opposite magnetic fields of the front and rear faces will aid in eliminating from the cathode, a tendency to collapse when heated to the high temperature required for certain installations.

Such an installation is disclosed in Fig. 1 where the cathode has its active face I0 closely spaced in parallel arrangement from a control grid 25.

This control grid in this disclosure is supported in parallel arrangement with the cathode face by a plurality of conductive rods 26, symmetrical with the two cathode standards l9 and 20, and these rods are sealed through a cup-shaped casin of insulation 21. sealed to a copper member 28 silver soldered to a disk 29 in turn silver soldered to a hollow body resonator 30 having openings 3| in a plane parallel to the grid face and the cathode face ID.

A supporting disk 32 and an adjusting screw 33, attached thereto, and screw threaded to the disk 29, permits the spacing adjustment of the opening 3| in the hollow body resonator to be spaced as desired from the cathode and grid. Inside of the hollow body resonator 30, is a receiving face 34 for the electrons, and this face may constitute a portion of a water-cooled electrode 35, which is either separate from or connected to the hollow bodyresonator as desired.

In place of the slots H in Fig. 2, we may utilize a ribbon of approximately 10 mils thickness, and then thin the active surface It) to a thickness of 5 mils by removing material from the back or front or both faces of the central portion of the ribbon, as illustrated in Fig. 3. The other portions 13, I4, I5 and I6 of the cathode ribbon The rim of this insulation 21 is ness will cause this face Hi to have a higher temperature.

In Fig. 4 we have illustrated a modification in which the slotted front face It) is the same as in Fig. 2, but the continuation of the ribbon from this front face is curved at into a rear face M parallel to and spaced from the front face. The end tabs 42 and 43 are bent downward on the one side and welded to the conductor or standards I9, 20. The magnetic field of the current in the front face In is more completely neutralized by the magnetic field of the current in the rear face 4| than in Fig. 2. The rear cathode structure of Fig. 3 may be modified in a manner similar to that of Fig. 4.

It is apparent that other modifications may be made in the preferred embodiments illustrated and, accordingly, we desire only such limitations to be imposed upon our invention as is necessitated by the spirit and scope of the following claims:

We claim: a

l. A cathode comprising a metal ribbon folded into a plurality of planes and means increasing the electrical resistance of the metal extending between folds thereof in one of said planes to exceed the resistance of the metal comprising said folds.

2. A cathode comprising a metal ribbon folded into a plurality of planes, the portion of the ribbon in one of said planes having slots therein substantially from one fold to another fold and the ribbon at the folds thereof being more conhave the thickness of corresponding portions in the modifications in Fig. 2. This reduced thickductive than at said slotted portion.

3. A cathode comprising a metal ribbon having an active plane slotted face and having continuations of the ribbon from said slotted face which oifer less resistance to current flow than said slotted face, said continuations having portions extending behind and rearward with respect to said slotted face for mounting and current conducting purposes.

4. A cathode comprising a metal ribbon having an active plane slotted face and a rear face parallel to said active plane slotted face, said front and rear faces having different resistance characteristics.

5. A cathode comprising a metal ribbon having an active plane slotted face and a rear face parallel to said active plane slotted face and formed as a continuation thereof and having greater conductivity lengthwise than the lengthwise conductivity of the slotted face, whereby the our- 7 rent in said front face will flow with greater

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