US2132946A - Electron discharge device - Google Patents

Description

K. FRITZ ELECTRON DI SCHARGE DEVICE Filed Oct. 28, 1936' INVENTOR KARL FRITZ ATTORNEY Patented Oct.,11, 1938 Q Q UNITED STATES 1 2,132,946 I ,ELEc'raoN mscnmca DEVICE Karl Fritz, Berlin,,Germany, assignor to Telefunken Gesellschaft flir Drahtlose. Telegraphic m. b. 11., Berlin, Germany,

Germany a, corporation, of

Application ctober 28, 1936,, Serial No. 107,917

In Germany October 16, 1935.

.8 Claims. 01. 250-275) My invention relates to electron discharge devices more particularly to magnetrons in which the electron flow from the cathode to the anode is subjected to the action of a magnetic field.

Themounting of the discharge system, especiallythe shaping and positioning of the electrodes in the present invention is based upon novel viewpoints, which take into proper consideration the paths which the electrons: travel subject 'to to the axis of the system; The purpose of the inventionis the production of a greater working slope in' order that smaller control or -modula-' tion powers may be made to 'sufiice in practice- Inthe prior art, in magnetroni tubes which are furnished" with arcuate anodes placed concentrically with reference to the cathode, auxiliary electrodes "of similar form maybe" mounted in the 'gapsbetween the anodes so that both kinds of electrode come to beplaced on a circular cylinde'r' andwill be at the same distance from the cathode as from the anode.

It is also known from the prior art'to use plane electrodes in magnetrons positioned upon the sides 25, of airectangle; In'this case arrangements were madeso that the anodes (working, electrodes or active electrodes) were placed" at a greater dis=- tance from the cathode than the auxiliary elecrodes so that, more particularly when operating with a positive biasing voltage, the auxiliary electrodes absorbed a considerable part of the emission current, and caused considerable interference in'the discharge process between the anod'esand the cathode. What would alsoappear important is to point out that these auxiliary electrodes merely served to provide spatial closure so *formed and disposed that they touch an imaginary circular cylinder concentric. to the cathodeat only one or at only a few places, while not coinciding therewith, at least not completely,-

and that the auxiliary electrodes are mounted outside the said imaginary circular cylinden- In order that the effect of the auxiliary .jelectrodes may be madeas great as possible they are mi lilte the action, of a magnetic field extending parallel edinside an area which, when viewing,a section at right. angles to the cathode,'is bounded on the one hand by the circle about the cathode, and, on the other'hand, by the anodes or their extensions.

y In other words, this novel disposition makesiit feasible to abandon the. conventional magnetron construction in'which, between the cathode and the anode no further electrodes are mounted. Hence, inthis special instance, the auxiliary electrodes maybe accommodated inside the discharge space without the risk of their absorbing appreciable current evenwhen a positive biasing voltage is impressed'upon them. The physical explanationof this fact will be found below.

i 'The'magnetron arrangement according to the invention is preferably so made that (1) the anodes (the workingelectrodes) are disposed upon the sides of a parallelepiped, and that, (2) the axially directed magnetic field and the operating potentials are so chosen that the electrons on their'trajectories or paths about the centrally positioned cathode roughly are tangent to the anodes; and that (-3)- the auxiliary electrodes are providedat those points of the discharge system which are devoidof circulating electrons or nearlyso. a i

' The dischargespace proper may be regarded as onlyinthe interior of the imaginary cylinder which; must 'be conceived as the pathboundary of the circulating electrons. -However, owing to theiact that the auxiliary electrodes come closer to the discharge area or region the electrons will fbe subjected more markedly than heretofore by the electrical auxiliary fields.

Hence, the control or modulation fields which must be made available are smaller, i. e., the slope of the characteristic is steeper, where J1-J2 is the amplitudediflerence of the component. anode currentswhen subject to the action of a control potential U. 1 1

The novel features which I believe to be characteristic of my invention are set forth with particulality in'the 'appended'claims, but the invention itself willbest be understood byreference to the following description taken in connection with the'aecgmpanying drawing in which Figs. 1 to 6 inclusive are diagrammatic transverse sections, of different forms of electron discharge devices embodying my invention and Fig. 7 is a diagram of a circuit including an I electron discharge-device made a a ins my nt pn- In Figs. 1 to 'Iiare shotrn exemplified embodiments of the basic idea of this invention. In Fig.

1 the anodes for anode segments A are disposed 7, along the sides of a quadrangle. The circle about the cathode K with radius Ta indicates the points beyond which the electrons will be unable to travel, provided thatthe magnetic field is suithas been made of a suitable value.

absorb any appreciable current even in the presence of a positi e biasing potentialm of Fig. '1. The anode portions 'A, of the anodes which are in positions posterior in reference to the auxiliary electrodes H, are shortened sofast'o diminish capacitance between themi A5 a matter of fact, these particular portions of the plates may be dispensed with'inasmuch as they do not produce any appreciable effect upon the discharge process and action owing to the shielding set up by the auxiliary electrodes H. The auxile iary electrodes themselves may be made of any desired form at all.

Fig.3 shows the sectionlaid through a rectangular electrode system. The anodes A are located upon the long sides and the auxiliary electrodes H on the short sides of a rectangle.

The anodes of the magnetrontube need not be of planar configuration, but they may be made ofany desired forms. The only factor which'is important is that the anodes'should not entirei y come eloseto the boundary cylinder aroundtl ie cathode, but should-at some places be spaced ing of"the"a uxiliary electrodes. p a

Fig. 4 shows an it exemplified embodiment in which the anodes A udiich touch the circle about the 'cathodealongfa" medium line, are not made therefrom in order to afford room'for the mountplanar or flat; but so shaped that the parts'of the anode located" at both sides of the tangent point are "replicas? of one another. I Ifthe auxiliary electrodes are moved out on the" anode surface, there" results a construction as shown by way of exampiein Fig. 5. The anodes are flat and planar, and they touch the circle described about the cathode at one lateral edge; The auxiliaryelectrodes are positioned in the extended planes of the surface of the anodes, the tangent being the edge of the anodes. i

Now,- it would be feasible to go one step further by making the anodes andthe auxiliary 'electrodes of like size while placing them symmetrisally with respect, to adia'meterroi the circle about the cathode so that thetangent pointcoincides with the gap between the anode A4 and the corresponding auxiliary electrode H4 as in Fig. '6. In this latter' disposition it should be observed thetowing to the direction of travel of the electrons under the infiuence'of a'magnetic field as here chosen theelectrodes H4 are not electrically equivalent to the 'workingelectrodes A4. Inasmuch as the electrons pass 'over essentially in the center of'theside'surface of the square, the slot S is not equivalent to the? slot S.

By a suitable choice'of the working conditions any undesired current control action by the anodes upon the auxiliary electrodes readily preventable; for instance, the auxiliary electrodes H4 can be operated at a D. C. voitage about lO to 20 percent lower'than the'anode R c-Folia v The felectronic decoupling of the anodes and the control electrodes could be further as sisted tend parallel. to the cathode K. The anode potential Us. and the magnetic field are so chosen that the 'major'part of the electrons on their paths or orbits will just about skirt the anodeA,

.and that the points Where auxiliary electrodes H Fig. shows a tube which is similar to thatv are mounted remain free from electrons, or

nearly so. The auxiliary electrodes H are preferably impressed with a positiire potential Uh for biasing, and this potential will usually be less than the anode potential. This auxiliary electrode potential may be superposed upon the master'potential, the modulation potential, or the incoming (signal) potential, etc. z

Practical experience has shown that it is desirable in reception with the magnetron to have ways and means available's o that regeneration and rectification may be regulated independently of each other. This problem may be solved in a particularly advantageous manner with the use of a tube as here disclosed.

In Fig. 7 the microphone *M may be replaced by a telephone receiver or an A. F. amplifier, or else. if an intermediate circuit is provided; an I. amplifier. The RF voltages; which are picked up by antenna E coupled to circuit F connected between the anodes A are superposed upon the anodes A; theanode system serving primarily for regeneration. Rectification itself is practically efiected only, by'the,,aid' of the auxiliary-eiectrodes H. The separation of the two actions which are fundamentally independent of each other, affords a chance to choose for bothjfunctions such operating points as wiil be of most advantage, and this has heretofore been hardly feasible. I 7

The working conditions, that is to say, mag-' netic field and biasing potential of the auxiliary electrodes and anodes are preferably so chosen that the auxiliary electrodes, in the absence of incoming or signal voltages, absorb only a small current or no current at all. As soon as asignal alternating voltage happens to be superposed upon the anode potential, the auxiliary electrode current rises roughly in direct proportion to the upon it asupersonic variation or super-regenerative bias volt so that the anode system will oscillate between the incipiency'and discontinuance of oscillations, provided the working point has been suitably chosen. Then a rectifier action is noted in the auxiliary electrodecireuit as described above. However, this does not mean that the biasingfrequency may not be applied to the auxiliary electrodes, if desired. v

i The basic idea of the invention is not confined to the embodiments here indicated by way of example. The anodes may be made of any desired form provided. that at some localpoints they are so far spaced fl'QIIli thG cathode that between them and the-cathode there remain a suitable number of places free from electrons suited to accommodate the auxiliary electrodes.

The various auxiliary electrodes may also be impressed with RF control potentials which are shifted in their phase relations as in a transmitter amplifier. The modulation voltages need not exclusively be applied to the auxiliary electrodes, in fact, recourse could be had to a combination modulation in'which upon the anode potential and the auxiliary electrode potential modulation waves are superposed in phase or in phase opposition.

What I claim as new is:

1. An electron discharge device having an envelope containing a straight cathode, a plurality of anodes surrounding and parallel to said cathode, and auxiliary electrodes positioned between said anodes, said anodes touching the surface of an imaginary cylinder having said cathode as its axis, said auxiliary electrodes lying outside of said imaginary cylinder and meansforproducing a magnetic field parallel to said cathode.

2. An electron discharge device having an en'- velope containing a straight cathode, a plurality of anodes surrounding and parallel to said cathode, and auxiliary electrodes positioned between said anodes, said anodes having a portion touchbounded by the anodes or their extensions, and

means for producing a magnetic field parallel to said cathode. h

3. An electron discharge device having an envelope containing a straight cathode, a plurality of anodes surrounding and parallel to said cath-.

ode, and auxiliary electrodes positioned between said anodes and parallel tosaid cathode, said anodes touching the surface of an imaginary. cylinder having said cathode as an axis, said auxiliary electrodes lying outside of said imaginary cylinder, said anodes and said electrodes forming an enclosure about said cathode, and means for producing a magnetic field parallel to said cathode.

4. An electron discharge device having, an envelope containing a straight cathode, a plurality of fiat anodes surrounding and parallel to said cathode, said anodes being tangent at their midpoint to the surface of an imaginary, cylinder having the cathode as an axis, and auxiliary electrodes positionedbetweensaid anodes and lying outside of said imaginary cylinder, and means for producing a magnetic field parallel to said cathode.

5. An electron discharge device having an envelope containing a straight cathode, a plurality of flat rectangular anodes surrounding and parallel to said cathode and touching the surface of an imaginary cylinder having the cathode as an axis, said anodes forming a rectangle about said cathode, and auxiliary electrodes positioned between said anodes and outside of said imaginary cylinder in the corners of said rectangle, and

means for producing a magnetic field parallel to the cathode.

electrodes absorb a minimum 6. An electron discharge device having an envelope containing a straight cathode, a plurality of anodes surrounding and parallel to said cathode, and auxiliary electrodes positioned between said anodes, said anodes touching the surface of an imaginary cylinder having said cathode as its axis, said auxiliary electrodes lying outside of said imaginary cylinder and means for producing a magnetic field parallel to said cathode, a source of voltage connected between said anodes and said cathode, and a source of voltage connected between said cathode and said auxiliary electrodes, said voltages and magnetic field being so chosen that the electron paths do not extend beyond the surfaces of the imaginary cylinder whereby saidauxiliaryelectrodes lie in spaces substantially free from electrons.

7. An electron discharge device having an envelopecontaining a straight cathode, a plurality of anodes surrounding and parallel to said cathode, and auxiliary electrodes positioned between said anodes, said anodes touching the surface of an imaginary cylinder having said cathode as its axis, said auxiliary electrodes lying outside of said imaginary cylinder and means for producing a magnetic field parallel to said cathode, a

source of voltage connected between said anodes and said cathode, and a source of voltage connected between said cathode and said auxiliary electrodes, said voltages and magnetic field being so chosen that the electron paths do not extend beyond the surfaces of the imaginary cylinder whereby said auxiliary electrodes lie in spaces substantially free from electrons, a circuit connected between said anodes and said source of anode voltage, and a circuit connected between said auxiliary electrodes and said auxiliary electrode voltage supply, said anodes providing regeneration and said auxiliary electrodes rectification independently of each other.

8. An electron dischargedevice having an envelope containing a straight cathode, a plurality of anodes surrounding and parallel to said cathode, and auxiliary electrodes positioned between said anodes, said anodes touching the surface of an imaginary cylinder having said cathoutside of said imaginary cylinder and means for producing a'magnetic field parallel to said cathode, a source of voltage connected between cylinder whereby said auxiliary electrodes lie in spaces substantially free from electrons, a circuit connected between said anodes and said source of anode voltage, and a circuit connected between said auxiliary electrodes and the auxiliary electrode voltage supply, said anodes providing regeneration and said auxiliary electrodes rectification independently of eachother, the magnetic field and biasing voltage of the auxiliary electrodes beingso adjusted that in the absence of radio frequency signal potentials the auxiliary of current.

KARL FRITZ.

. ode as its axis, said auxiliary electrodes lying

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