US2909702A - Discharge vessel cooled by radiation - Google Patents

Description

J. E. SCHEEL 2,909,702

DISCHARGE VESSEL COOLED BY RADIATION 2 Shets-Sheec 1 Oct. 20,, 1959 Filed May 20, 1955 J. E. SCHEEL DISCHARGE VESSEL COOLED BY RADIATION Oct. 20, 1959 2 Sheets-Sheet 2 Filed May 20, 1955 ,ifoachim Eric Scheel, Ettlingen, Baden, Germany, as-

metricdesilgh of the cathode itself or its coating, in

this kind of tubes. I The invention provides an anode in which are formed States Patent Ofiice 2,909,702 Patented Oct. 20, 1959 2,9 09,7o2 DISCHARGE-VESSEL COOLED BY RADIATION Signor to Siemens & Halske Aktiengesellschaft, Munich and Berlin, Germany, a corporation of Germany Application May 20, 1955, Serial No. 509,930

In Germany October 1, 1948v Public Law 619, August 23, 1954 Patent expires October 1, 1968 v This invention relatesto a discharge vessel co d y radiation.

The invention is particularly concerned with a discharge tube in' which may be expected strong heating of the anodes at which the work load is converted into heat due to the bombarding electron flow. In discharge tubes with radiation-cooled anodes, the cooling fin principle has been used untilnow, that is, cooling fins or ribs have been provided for conducting and radiating the heat away outwardly. M

The invention proposes a new way of radiation cooling I of such -anodes and is of' particular importance in connection vwith relatively high capacity discharge tubes provided with,indirectly heated cathodesof' relatively'low operating temperature; for example, oxide' cathodes. Such tubesare usually customary tubes with centrally disposed cathode of a system of several individual cathodes. About the cathode are arranged the individual electrodes among which may be one or more control'electrodes (grids), forming an inner system. One. or'fmore of these'la'tte'r electrodes mayeifect bunching or separatio ,re pectivelyf of the electron stream emanating from the cathode Separation or distribution of f the cathode streamer flow may also be effected bythe geo- 40 sectors, with an'emitting substance, alone or in cooperation with the action of the 'electrodes of the inner system.

This is the reason for referring to electron fiow from the cathode to the anode as taking place 'in diiferent flow sector-s. -'-The invention is of particular importance for two or more recesses-for individual electron flow sectors or for each flow sector emanating from the inner system, the'entire or atleast the prepondera'n't portion of the electron flow energy being converted into heat at the inner surfaces of said'recesses. The recesses are thereby suitably so designed that they project outwardly for relatively considerable distances and exhibit large interior surfaces ex- -tending at very acute angles to the direction of the elec- .tron' flow. Depending upon the design of the electrode system and the entire tube, it may be suitable to provide the recesses with their longitudinal extent and their aperture slots in parallel to the longitudinal axis of'th'e inner electrode system. The arrangement may otherwise be such that the recesses extend perpendicular thereto,

that is, with the aperture slotsarranged, for example, annularly or helically sector-likeabout the longitudinal axis of the inner electrode systeml -Theindividual recesses may also be formed differently, for example, cone-shaped 5 or in pyramid form. -A stretched form may in some cases be desirable so as to result in wedge-shaped forma- I tion with blunt or pointed ends. A plurality of recesses for a flow sectormay be disposed one directlynext to ..the other or one underneath the other, basesof two adjacent recesses merging The depthoffthe individual recesses may be substantially with the aperture 7 into oneanother.

V pyramid shape, projecting in the manner of thorns or barbs from the anode surface proper. It will, of course, be easier, for manufacturing reasons, not to provide a multitude of individual protuberances but always a series thereof in the form of striplike elevations or the like.

The-various objects and features of the invention will appear from the description which will be rendered below with reference to the accompanying diagrammatic drawings, wherein Figfl shows in schematic sectional view parts of a known tube system;

Fig, 2 shows a similar system comprising cooling recesses; Figs. 3, 4, 5a and 511 different shape; and o Fig; 6"s'hows a furtherembodiment Fig. 1, showing a symmetrically designed discharge system of which only one-half is represented, comprises a centrally disposed cathode 1, which may be, for examshow systemsv with. recesses of "ple, an indirectly heated oxide cathode. The-electron emitting coating is provided upon the oval surfaces of the cathode 1. Two electrodes 2 and 3 embrace the cathode slightly spaced therefrom. These electrodes may actas a first and a second grid of a discharge tube oper- .ating' as a'pseudo pentode (tetrode). Two metallic members 4;which are at cathode potential, limit the flow space, so that dischargesectors are formed respectively upwardly and in not illustrated fashion also downwardly. These metallic members '4 effect so to speak a focusing and,

being at cathode potential, may be considered a rudimentary suppression grid. Numerals 5 and 6 indicate the anode or plate which is in known manner formed in accordance with' the. cooling fin principle. The electron flow penetrating the inner tube system arrives at the relatively small inner plate surfaces 5 which are disposed more or less coaxial therewith, and the heat produced there is conducted with a corresponding temperature drop to theradiating cooling fins 6.

The realization of this principle leads especially in high capacity tubes to relatively heavy anodes made of thick material with numerous cooling fins some of which may extend perpendicular to the surfaces 6. The selection of the anode material is limited to anode material with the required heat conductivity over the small cooling fin cross-section in longitudinal direction of the corresponding surfaces. The cooling of the anode causes difliculties in allknown arrangements of this kind.

The invention'proceeds from the recognition of the observation that the cause of these difiiculties liesprimarilyin the fact that a part of the anode, in the known arrangements, absorbs heat, as is the case with the surfaces'5, while the other parts (surfaces 6) serve solely for giving off heat. It is in this connection immaterial whether or not grooves are being pressedinto the anode sheets of the known arrangements. 'In all these cases, the -preponderant part of the electron flow is caught by the coaxial inner surfaces 5 of the plates, such plates embracing the inner system with narrowest spacing and highest 'plate temperature'andthus adversely afiecting the heat stability of the system. Special measures must oftentimes be taken in order to prevent in the case of oxide cathodes, an undesired thermal emission of the grids neighboring the cathode. The unfavorable ratio between production costs and expenditure and weight and obtainable results with cooling fin anodes leads in high capacity tubes above all to larger structural dimensions than would v.be either necessary or suitable without these limitations.

As compared with these known constructions, the invention makes it possible to design the anode so that the same surfaces which are exposed to the heat are also utilized for giving off heat.

In the tube according to the invention, a system of surfaces is being used, in place of the cooling fin anode indicated in Fig. 1 at 5 and 6, which, which is formed and arranged so that an anode is produced which is provided with recesses forming openings in the direction of the electron flow directed thereto. The design of these recesses is in connection with auxiliary means to be presently described, such, that the electron flow is wholly or partially converted into heat at the inner surfaces of the recesses. These inner surfaces may be formed very much larger than the relatively small coaxial impact surfaces of the cooling fin anode. The number of recesses, their arrangement, form, depth, aperture, width, etc., depends upon the inner system of the tube and the operating conditions thereof. This is particularly important when great load densities are to be coped with, as they occur, for example, with indirectly heated cathodes as electron flow sources.

In Fig. 2 is shown an embodiment, in schematic sectional view, which corresponds in essential details very much to the known structure shown in Fig. 1. The inner system has the identical electrode structures 1, 2, 3, 4, having however instead of the cooling fin anode 5, 6 of Fig. 1, an anode in which are formed recesses, 8 defined by sloping walls 7. Similar to Fig. 1, only the upper half of the system is being shown in Fig. 2, comprising three recesses 8 with apertures for the incoming upper electron flow sector lying relatively to the inner system extending approximately coaxial thereto. The electron flow impacts preponderantly the straight or nicked wall surfaces 7, and its energy is there converted into heat. The total surface of the walls 7, impacted by the electron flow, may, in otherwise identical conditions and depending upon the number, depth and form of the recesses may be increased to a multiple of the impact surfaces 5 of the cooling fin anode of Fig. 1. The inner surfaces formed by the walls 7 alone determines the reflected heat radiation in the direction of the inner system. The path of the heat from the heat-receiving walls 7 to the outside depends upon the wall thickness and the heat conductivity of the anode material used.

The invention offers in view of this situation the further advantage that extraordinarily thin and light plates may be made of sheet material or wire mesh or the like. It is furthermore possible, in view of the thin wall dimensions, to use material with relatively low heat conductivity, thus removing the limitations as to plate material in the selection thereof.

It may be suitable in many cases, to make the recesses dissimilar, as indicated in Fig. 2 by the greater depth and aperture width of the middlemost recess as compared with the two adjacent recesses, and as also indicated by the legs 23 and 24. By suitable design of the recesses or their number, the energy of part of the electron flow will be converted into heat directly at the ends 29 of the recesses, that is, considerably farther away from the inner electrode system as is, under otherwise similar Conditions due to the development of a virtual cathode, possible in the case of anodes provided with cooling fins.

In addition to the radiation advantages obtained, there appear in pentode operation, the advantages of a farreaching suppression of the secondary emission exchange between the anode and the inner electrode system, because the recesses act as cages so far as the potential is concerned. This in turn gives, for example, the possibility of a greater variation in the screen grid potential than is possible in an anode provided with cooling fins with space charge threshold according to Fig. 1.

A good utilization of the anode space is connected with a predetermined minimum number of recesses per elec* tron flow sector. Accordingly, to each flow sector,'there is allotted an anode sector with two or more recesses. The upper anode sector with the three protuberances' 8 shown in Fig. 2 corresponds accordingly to the upper electron flow sector.

The intended effect may if desired be supported potentialwise by a pre-anode which may be formed, for example, gridlike, especially of a small number of highly loadable wires. Such pre-anode is either directly con nected with the anode or by an electrode 9 which may be combined therewith as diagrammatically indicated in Fig. 2. However, a spatially separate pre-anode may be provided.

In the embodiment shown in Fig. 2, it will be impossible to avoid always a strong heating of the aperture legs 23 and 24. In order to obtain a lower loading of these legs, other measures may be applied which are diagrammatical ly indicated in Figs. 3, 4, 5a and 5b.

In the embodiment shown in Fig. 3, the upper sector, extending from the inner electrode system 1, 2 and 3, is electron-optically linked with the electron 'flow directed into two recesses 12 illustrating the upper anode half. For this purpose, there is provided a bar 11 between an ode and grid 3 extending in parallel to the longitudinal axis of the tube system in the symmetry plane which projects through the center of the cathode and the common aperture base 13 of the two'anode recesses 12. The bar 11 may be potentialwise connected with the limiting elements 4 or may be connected to a separate fixed or functionally dependent potential.

The limiting elements 4 and the bar 11 as well as by the recess bases 13 and 25 form an electron optical lens system. A suitable geometric scheme, preferably in the design in the vicinity of the recess bases 13 and 25, in connection with suitable operating potential ranges, will make it possible to provide for a sufficiently satisfactory electron optical guidance of the electron flow as well as a potential influence in the anode space resulting there rom.

For this purpose, the base 13 which is common to recesses 12 may be made considerably more rounded and wider than would be tolerable loadwise with the bases 23 and 24 according to Fig. 2. The more pronounced rounding at the bases 25 and interiorly of the walls 10, in the direction of the recess centers, acts in a cooperative supporting manner and permits a desired surface distribution of the impacting electron flow the energy of which is converted into heat primarily along the walls 10. The surfaces of the bases '13 and 25 can be held sufliciently free of this effect. The design and potential conditions of the bar 11, under some circumstances with the elements 4, may be effected with consideration of the electron optical properties of the lens system. The suppression grid effect thereby additionally occurring, which becomes operative in predetermined embodiments and under predetermined operating conditions, and which can be utilized therewith, is for the invention only of subsidiary importance.

Fig. 4 shows a further embodiment of the invention. There are in this case three recesses formed in the anode, only the central and deepest recess being mirrorsymmetrically formed relative to the cathode axis. Assuming an analogous symmetric effect in an electron optical lens system, as is created by the bars 20 relative to the bases 26 and which is operatively a function of geometry and the potentials connected, the two walls 14 of the central recess will be likewise mirror-symmetrically impacted by the electron flow.

Contrary thereto, the walls 15 and 16 of the left recess and also the walls 17 and 18 of the right recess are even with sufiicient symmetry operation of their lens systems differently impacted by the electron flow. In the left recess, there will at any rate occur a stronger impacting of the angularly extending wall 15 as compared with the impacting of the oppositely disposed 'laterally' bulging wall 15 In -'corresp'ondi'ng' mannerjtlie inclined wan 1 8 wiu-Betmpaaed more "strongly than the less inclined wall1 7.:

In some special cases,

the radiation of the heat produced maybe increased by the provision, in known manner, of cooling fins. This is indicated in connection with the 'right recess by the cooling fin 19 extending from the impact wall .18. 'similarfins may extend ,from the walls 15 and 16 of the left handjrecess. a The geometry of the electron'opticsfis'in Fig.1,4 eifected by. the bases 26 in cooperationwith' th e oppositely extending ends of the elements '4 and the two bars 20. If an'electron optical influence off'the electron impact distribution upon the individual impact walls of a recess of a givenanode is desired, itma'y be obtained by a nonsymmetric'ally operating electron optics. Such nonsymmetry may be obtained, for example, in the position and form of the elements 4 and the bars 20 or by different potential connections in the right and left elements 4 and the two bars 20, which in such a case must not be oonductively connected. It is in this manner also possible to obtain in the operation of a completely symmetrically designed tube, such as is for example indicated in Fig. 3, nonsymmetry in the impacting of the four impact walls 10, by not connecting the elements or members 4 one with the other and directly with the bars C111, but placing them on suitable fixed or functionally dependent potentials.

Figs. 5a and 5b show a further embodiment of the invention, Fig. 5a indicating a longitudinal section and Fig. 5b a transverse cross-section of a modified design of the recess formation. The allotting of the anode recesses to the inner electrode system of the tube is here difierent than in Figs. 2 to 4. As compared with these examples, the recesses are displaced by 90. The parts of the lens system designated by numeral 21 are correspondingly displaced, such parts being formed as parts of an angular grid, as is particularly apparent from Fig. 5b. It is again important to provide for geometric conditions in the corresponding parts of the optics which is formed by the bars 21 in connection with the recess bases 27. In case the bases 27 extend perpendicular to the axis, the electron optically effective parts of the bars 2'1 will by their parallel arrangement to the bases 27 also form wholly or partially closed rings extending perpendicularly to the longitudinal cathode axis.

It is however also possible to proceed from a spiral thread line instead of from the individual rings or ring sectors, in which case the bars 21 will represent a spiral or be part thereof. In such a case, the recesses will likewise form sectors of a spiral with the bases 27. Four recesses are shown in Fig. 5a, the eight impact walls thereof being indicated by numerals 22, all of them being allotted to a single electron flow sector of the inner system.

The electrodes of the inner electrode system 1, 2 and 3 are for the sake of simplicity represented as corresponding to the system design shown in the remaining figures. The tube in accordance with the number of its electrodes would constitute a tetrode or a pentode. There is however no reason for limiting the invention to such multigrid tubes. Even in the presence of such a number of electrodes, the grid 3 may, for example, be connected with the recessed anode, as an auxiliary electrode, thus permitting obtaining regarding the anode recesses, the action of a triode with electron optics. The grid 3 may also be eliminated, resulting in a simple triode with electron optics. It is furthermore possible to use a directly heated cathode instead of the indirectly oval cathode shown in the drawings.

Fig. 6 shows a further embodiment. The anode forms in this embodiment a variant of the anode shown in Fig. 3. It is produced by arranging the ends (points) of the two recesses 12 (Fig. 3) in common, along the symmetry plane formed by the cathode center and the bar 11, thus producing for both recesses only one recess point; 'The rod"31" of "circularcross-section shown in Fig. 6, corresponds to the medianbase 13 of the recesses 12 of Fig. 3. A cooling-effecting connection of the base 81 with the common point of the two re'cesses mry in this case be dispensed'with. E'ach of the two recesses therefore partakes only with one side wall in receiving its allotted pairtofthe sector electron flow. The side walls 30 of the recesses combined at their ends, as shown in Fig. 6, accordinglycorresponding to the two outer side walls/ 100f the recesses '12 of Fig. 3. Numerals 34 indicate cooling fins projecting from the wall 30. The bases 33 correspond to the bases 25"of Fig. '3.- I

i The member 31 shown in Fig. 6-which-forms a base for utilizing'thespace formed by the walls SQ-i'n'the manner of two recesses-"need not be cross-sectionally circular; it may be cross-sectional rectangular,- dropshaped or thelilie, as may be required or desired in ac cordance with the problem posed; 7 I ii i As in all embodiments according to the invention, the spacing between the individual bases of the recesses from the inner system of a tube may be different. In Fig. 6, there is provided an auxiliary electron optical distribution of the electron flow sector emanating from the inner system. The geometric design of the optics is formed by the bases 33 and 31 in connection with the electrode elements 4 and 32, analogous to the optics of Fig. 3, the bar 32 of Fig. 6 corresponding thereby to the bar 11 of Fig. 3.

Changes may be made within the scope and spirit of the appended claims.

I claim:

1. In an electron discharge tube having an inner system of electrodes including a cathode, electron streams emanating sector-like from said inner electrode system, an anode adapted to prevent development of a virtual cathode and to dissipate by radiation heat developed due to the imact of electrons thereon, said anode having for each one of some of said electron streams at least two operative recesses formed therein for the reception of respective portions of the associated electron stream, said recesses being defined by wall means extending outwardly v in directions away from the cathode and angularly relative to the direction of the respective electron stream to relieve the regions extending about the openings of said recesses substantially of the impact of electrons thereon and to form angularly outwardly directed heat radiating surfaces so as to effect cooling during the operation of the tube, and electron-optical means interposed between the cathode and said anode to control the electron flow into said recesses.

2. A structure and cooperation of parts according to olairn 1, comprising an electrode element disposed as seen in the direction of electron flow ahead of a recess, said electrode element constituting a base for deflecting the electron stream so as to form the effect of two recesses.

3. A structure and cooperation of parts according to claim 1, comprising auxiliary electrode means disposed 1alhead of said anode as seen in the direction of electron 4. A discharge tube according to claim 1, wherein the longitudinal dimensions of said recesses and the openings thereof extend in parallel with the longitudinal axis of said inner system.

5. A discharge tube according to claim 1, wherein said recesses are with their openings arranged annularly about the longitudinal axis of said inner system.

6. A discharge tube according to claim 1, wherein the openings of said recesses are arranged in convolutions about the longitudinal axis of said inner system.

7. A discharge tube according to claim 1, wherein the individual recesses for an electron flow sector are disposed adjacent one another.

8. A discharge tube according to claim 7, wherein the: bases of two adjacent recesses merge one into the other.-

9. A discharge tubeaccording to claim 8, wherein said bases are in the electron flow direction relatively nar* row.

10. .A discharge tube according to claim 1, wherein the depth of said recesses exceeds the width of the open ings thereof.

'11. A discharge tube according to claim. 10, wherein said recesses areof different depth.

12. A discharge tube according to claim 10, wherein the openings of said recesses are-of difierent width.

13. A discharge tube according to claim 1, wherein said wall means are of arcuate shape.

14. A discharge tube according to claim 1, wherein said wall means are of irregular configuration.

15. A-discharge tube according to claim 1, wherein said 'wall means are shaped soas to effect subdivision of the .electron stream impacting thereon, and comprising an auxiliary electrode disposed ahead of said anode.

l iefierences Cited in;the -ii.le of-this patent UNITED STATES PATENTS 'Lederer Aug. ,1, Holst et a1. Oct. 27, Taylor Oct. 13, Haefi et a1. Dec. 17, Thompson Aug. 26, Haeif June 2, Litton Feb. 2, Van Over'beek Feb. 1, Skellett Feb. 19, Jonker Nov. 21, Sloan June 19, Sloan June 9,

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