US2235497A - High frequency electron discharge device - Google Patents

Description

0. HQEIL' March 18, 194-1.

HIGH FREQUENCY ELECTRON DISCHARGE DEVICE Original Filed Feb. 23, 1935 2 Sheets-Sheet l INVENTOR Oskar H eLL 0. HEIL March 18, 1941.

HIGH FREQUENCY ELECTRON DISCHARGE DEVICE 2 Sheets-Sheet 2 Original Filed Feb. 23, 1935 Fig. 7.

Patented Mar. 18, 1941 UNITED STATES PATENT OFFICE 2,235,497 men FREQUENCY ELECTRON mscnsnen navron hell, Indwifen-on-the-Rhine, Germany, ignor to o Corporation of America, New York, N. 2., a corporation of Delaware ary 23, 1934 paratusfor producing short electromagnetic waves.

Asis well known, undamped short electromagnetic waves are producedeither by the back coupling method utilized in connection with long waves, or by an arrangement utilizing oscillating electrons, for example as proposed by Barkhausen and Kurz, or by means or an arrangelo ment utilizingrevolving electrons, suchas the magnetron.

The present invention is based on an entirely novel principle of short .wave generation, and neither back coupling, nor revolving electrons are utilized therein.

In 'order that the invention may be well understood, a few fundamental definitions will be first of all referred to.

The Faraday cage is a hollow metal body. It

has the property that an electric charge located e in its interior has'the same relation towards the exterior, as if it were located on the metal. Therefore, an electron located in the hollow a 'space of the Faraday cage has the same eiiect outwardly asif ithad settled on the metal itself,

and hence movement of an electron within the cage has no effect on the cage and changing voltage on the cage has no eiiecton an electron within the cage since the interior of the cage is a field free space.

It is furthermore known that an electron in flight approaching a conductor or receding there from represents an electric current away fro or towards said conductor.

. The invention will now be explained, remem- 3 to 4 no observation can be made outside. The

effect is the same as if the electron had settled on the metal of the cage. when, however, the

electron leaves the Faraday cage at 4 there will be a sudden current in the opposite direction, since the electron is now receding. It is lmderstood of course that a circuit is connected between the cage 2 and cathode 5 and collector 6, and that proper voltage sources are connected 55 between cathode 5, electrode 2 and collector 6 "period of dwell,"

. t (c 250-2i.5) This invention relates to a method of and apto make electrons move from cathode 5 to collector 5.

In the whole of these considerations the most important factor is the time during which the electron moves in the cage. For brevity this 8 period of time will hereinafter be referred to as The length of the period of dwell is proportional to the distance 3-4 and inversely proportional to the velocity of the electron. If the distance 3-4 is a fixed one, the 10 period of dwell or transit time of the electron through the hollow electrode depends solely upon the velocity of the electron. If the Faraday cage is caused to be strongly positive as compared to the electron emitting cathode 5, then electrons 1B of great velocity will fly therethrough and the period of dwell will be very short. If the Faraday cageis caused to be only slightly positive as compared to the cathode, then slow moving electrons will fly therethrough-and the period of 80 dwell will be very long. If a very rapidly alternating potential is applied to the Faraday cage in the form of oscillations of very high frequency,

then the period of dwell will depend upon the potential to which the Faraday cage is raised at the instant the electron enters. While the period of dwell elapsesthe potential of the Faraday cage is altered, so that when the electron emerges therefrom the cage will be at a diffeernt poten- 3 tial.

The most important fact which may be deduced from the preceding considerations is as follows: Electrons entering the Faraday cage during the negative half period are slow and will not leave the cage until the following positive half period. 35 Electrons entering the Faraday cage during the positive half period are fast and will mostly leave the cage during the same half period. More specifically if an unmodulated stream of electrons is directed through the hollow elec- 40 trode and assuming an alternating voltage is applied to the electrode, the electrons approaching the electrode will be either accelerated or decel erated depending upon the voltage at the moment applied to the electrode, that is, electrons at will be accelerated ii the voltage on the electrode is beginning or is in its positive half cycle or will be decelerated if the voltage is beginning or is in its negative half cycle. with any hollow electrode, since the space within the electrode is all at the same potential, that is is a field free space, the speed of the individual electrons .through the electrode will be that which the individual electrons have upon entering the hollow electrode, that is, the accelerated electrons will continue to move rapidly at a constant speed through the electrode and the decelerated electrons at a. slow constant speed through the tubularelectrode. The result is that the fast electrons overtake the slow electrons causing a resulting change in the density of different portions of the electron beam, with a dense cloud of electrons separated by sections where the electrons are few. The extent to which this action takes place is determined by the length of the tube and the transit time or speed of the electrons. This space within the hollow electrode may thus be considered a space where the electrons drift to form the dense and rarefied portions of the beam and the result is a density modulation of the electron stream.

Considering now the electron balance ofv the Faraday cage the result obtained is asfollows: In the negative half period the ingress of electrons is predominant. In the positive half period the egress of electrons is predominant. But a negative body becomes more negative by the inress of electrons and a ,positive body becomes erator.

Further and in more detail, as the electrons leave the hollow electrode, depending upon the cycle of the applied voltage, .the electrons will either give up or take away energy from the electrode. If the electrons leave during the positive portion of a cycle, they are slowed down and give up energy to the electrode, thus producing an inductive output effect and inducing a voltage in the electrode. On the other hand, if the electrons leave during the negative portion of the cycle, they are accelerated and absorb energy from the electrode. Normally this hollow electrode when incorporated within a tube of the kind under consideration has such length and the voltages applied are such that there is a net transfer of, energy from the electrons to the electrode, which if applied to an oscillating circuit' connected to the electrode may be used to furnish the modulating voltage to the electrode. On the other hand, if. the electrons are first modulated before being directed through the tube, the electrode can be used as an inductive output electrode. The frequency at which the electron stream is modulated, the natural period of frequency of oscillation of the tubular electrode and its associated circuit, and the transit time of the electrons may be so adjusted that the oscillating circuit will receive energy from the modulated electron stream.

It will be apparent from the foregoing that according to this invention apparatus for producing short electromagnetic waves comprises, in

an electron discharge tube, hollow metal bodies adapted to form electrically oscillating electrodes and caused to perform such oscillation by electrons flying therethrough'.

.Some details will now be described which apment of the invention.

In the production of very short waves the flight of the electrons to the hollow metal body and the flight of the electrons away therefrom must be very rapid. This maybe achieved by disposing between the cathode and the hollow metal body. or hollow metal body and the anode a strongly positive grid (accelerating electrode), or by disposing a positive grid around the hollow body.

Preferably, the electrons are caused toform a pencil or beam by providing a negative electrode surrounding the cathode after the manner of a Wehnelt cylinder. This makes it possible to utilize smaller hollow metal bodies and the capacity of same will be small.

The said negative electrode or a control 'grid may be utilized to control theflow of the electrons. 4 This will enable the-waves to be generated to be conveniently modulated by an oscillating circuit connected between the cathode and control grid.

A double system, with two opposing hollow bodies, may be disposed in a single electron dis- .charge tube. To these hollow bodies may be connected Lecher wires or some other oscillating circuit.

The velocity of the electrons which have passed through the hollow metal body diii'ers. A number of them passes through the hollow body practically without loss, a small number of them loses speed. Therefore, if the anode of the electron discharge tube is made strongly positive, all the electrons will reach it. .But they will strong- 1y heat the anode, so that the tube will operate with poor efliciency. If on the other hand, the anode is caused to be only slightly more positive thereby thrown to one side and may be. intercepted by a further auxiliary anode. Instead of the slanting anode V-section anodes may be employed. The said auxiliary anode may-surround the whole system cylindrically. It picks up all energy losses and, if required may be cooled from p outside by water, air or the like, so'that even very large power tubes become manageable.

The heat generated in the interior of the tube by the impact of very fast electrons with the hollow body, the positive grid and the anode plate proved tobe a certain defectof the method de: scribed in the foregoing. To remove this defect it is proposed to provide the hollow metal body acting as electrically oscillating electrode with ertures for the. passage of electrons or .rays of electrons, said apertures again corresponding to.

the section of the rays of electrons. i

The provision of apertures in the hollow metal metal parts.

With a view to concentrating the rays of electrons and to reducing thecapacity between the accelerating electrodes and the hollow metal bodies it is advisable to provide the apertures of the hollow metal bodies .and of the accelerating electrodes with projections. These projectionsmay be in the form of funnels disposed either vertically or at an angle relatively to the said apertures.

In carrying intoeffect the method according to the invention it appeared to be of particular advantage to provide the braking and intercepting electrodes (anodes) in the form of a plurality of parallel metal plates insulated one from the other and disposed in the direction of the electron rays, said plates also having apertures corresponding to the section of the rays of electrons. The plates are not disposed at right angles but in a slightly inclined position relatively to-the direction of the electron rays and the potential of successive plates is gradually more and more negative. As a result, only slow electrons number of the plates employed the smaller will be the'heat generated by the impact of electrons.

In carrying into efiect the present method itis of advantage not to 'employ a very high vacuum in the electron discharge tubes utilized, so that narrow pencils of high electron current may be obtained. In this manner a certain ionic space charge is obtained which compensates and even over-compensates the space charge due to the electrons.

Because of the high mass of the positive ions their inertia will be so high that the ions can be considered stationary as far as the efiects of high frequency fields are, concerned. 'Therefore, the presence of a small amount of gas will enhance the operation of the high frequency tube by neutralizing the detrimental efiects of the electronic space charge.

The nature of the invention will now be explained by reference to the accompanying drawings, it being understood that it is not'intended thereby to limit the invention to the specific embodiments illustrated in the drawings. It is obvious that those skilled in the art will be able to devise other embodiments without departing from the spirit of the present invention.

Figs. 2, 3 and 4 are diagrammatic cross sectional views of apparatus constructed according to the invention.

Fig.= 5 is. an elevation of apparatus shown in Fig. 4.

Figs. 6, 7 and 8 are diagrammatical cross sectional views of the hollow metal body and the accelerating electrode. 1 I

Fig. 9 is a diagrammatic representation of the complete electrode arrangement.

Referring now to Figs. 2 and 3, two plates 8 iorming the negative electrode are arranged adjecent to the cathode 5. Said negative electrode 8 focuses the electrons emitted by the cathode into two oppositely disposed beams and directs said electrons. The electrons are given a very great velocity by the positivegrids I (acceleratingelectrodes) and fly transversely through the hollow metal bodies 2 to the anodes 6, producing oscillations in these metal bodies 2.

More specifically the electrons from the cath- 78 ode 5 are formed into beams by the negatively trodes being indicated at 'I.

and shielding element orgrid I, a hollow induc tive output electrode 2, a second accelerating and shielding element or grid 1 and then collected by an auxiliary collecting electrode or anode 8. The electrodes may have various shapes but in each the. output electrode is shielded from the cathode by the accelerating or shielding electrodeand from the collector by a second accelerating or shielding electrode. As pointed out above, electrons which approach the hollow tubular electrode 2 during the negative half cycle are slowed down and leave during the next positive half cycle whereas electrons approaching the electrode 2 during a positive half cycle are accelerated and leave the hollow electrode during the same half cycle. Thus the velocity of the electrons is modulated in the space between the first accelerating electrode I and the hollow tubular electrode 2. After entering the space within the hollow electrode the electrons drift through at the velocity which they had on entering the electrode since no field influences their movement through the electrode. As a result the fast electrons overtake the slow electrons within this drift space and leave the tubular electrode 2 in more or less well defined groups so that portions of the beam are more dense than other portions. This results in a change of density of different portions of the electron stream. Since the electrons leave the electrode during the positive half cycle they tend to slow down due to the positive voltage on the hollow electrode but on doing so give up energy to the electrode 2 so that any oscillating circuit connected between this electrode'and. the accelerating electrodes I receives energy from the decelerated electrons. It is for this reason that the device will remain in oscillation and act as an oscillating generator.-

In Fig. 3, in addition to the anodes 6 whic in this case are disposed at an angle relatively to the direction of the rays of electrodes, there are providedauxiliary anodes 9 (braking and intercepting anodes) which intercept the slow electrons, that is slow electrons having less energy than the faster electrons are deflected by electrode 6 at low positive potential to the collector electrode 9 at the higher positive potential.

Fig. 4 illustrates how' the additional anode 9 may be disposed to surround the whole system in the form of a metal shell.

Fig. 5 also illustrates the connection of the hollow metal bodies acting as ocillating elec-- trodes to the Lecher wires l0.

Figs. 6. 7, 8 and 9 show various possible embodiments'oi the hollow metal beds and of the accelerating electrodes, the hollow metalbodies being indicated at 2 and the accelerating elec- Tne directed pencils of electrons pass through the apertures ll of the hollow metal body and the apertures I! of the accelerating electrodes in the direction of the arrow shown. The hollow metal bodies are preferably cylindrical. but they may be composed of plane plates, as shown in Figs. 7 and 9. If the pencil or beam of electrons is of point or circular section rather than rectangular as in the case of a ribbon shaped beam, the said hollow metal bodies may be structuresmevolutioxiarily symmetrical. to the direction of the pencil of electrons that is the electrodes 2 may be-tubular members. The projections of the hollowmetal bodies are indicated at l3, and those of the accelerating electrodes at H. The projections may be disposed at right angles or slantingly with respect to the corresponding apertures of the hollow bodies or accelerating electrodes.

In Fig. 9 the cathode emitting the electrons is indicated-at 5 and-as shown it is surroundcdby the negative electrode 8 which focuses the electrons in a pencil or beam and-directs them. The electrons are accelerated by the positive elec trode I and after passing through the hollow metal body 2 impinge upon the inclined braking or intercepting electrodes 6. The plate first passed by the electrons is strongly positive, and each successive plate is less positive than the preceding one. The electrons flying through the apertures of the plates are gradually braked and caused to turn around. The electrons entering at a low speed are caused to turn around sooner, the fast' electrons later, having turned around the electrons are deflected laterally owing to the slanting disposition of the plates and fall on the rear face of the plate through which they have just passed. The path of the electrons is indicated in dotted lines.

In Figure 10 the electron discharge device comprises a cathode 5 and beam forming electrode 8' adjacent the cathode. The collector electrode 6' has positioned between it acceleratingelectrodes 1' and hollow electrode 2. The elec tronstream from the cathode 5 may be modulated by a control grid 9' positioned between the cathode 5 and the first accelerating electrode 1', the modulating signal being applied between the cathode 5' and grid 9' by an input ill. The output H' is connected as suggested above to the output electrode or hollow electrode 2'. In this arrangement the electron beam may be mod-v ulated before it enters the space between the two accelerating electrodes. This permits the use of the tube as an amplifier as well as an oscillator.

It is obvious that instead of utilizing the electrodes 5 and 8' for forming the pencils oi elec between said accelerating electrodes, and electron intercepting anodes, said apertures in said hollow metal bodies and in said accelerating electrodes being of a shape corresponding to the section of the pencil of electrons, and said electron intercepting anodes comprising a plurality of. parallel plates insulated from one another, said plates being disposed at an angle to the direction of the pencil of electrons and having apertures corresponding in shape to the section of thepencil of electrons, and said apertures in said plates being disposed in the direction of the pencil of electrons.

2. An electron discharge tube for producing short, electromagnetic waves comprising an exhausted envelope, cathode means within said envelope for emitting electrons, anode means within said envelope for intercepting said electrons,-

hollow metal bodies each'hav'ing apertures and being connected to a lead wire and disposed be-,

the pathof saidelectrons, and accelerating electrodes provided with apertures mounted between said hollow bodies and said cathode means and said anode means respectively.

3, An electron discharge tube for producingshort electromagnetic waves comprising an exhausted envelope, cathode means within said envelope for emitting electrons, anode means within said envelope for intercepting said electrons, negative electrodes adjacent to saidcathode means, hollow metal bodies each having apertures and being connected to a lead wire and disposed between said cathode means and anode means in the path of said electrons, and accelerating electrodes provided with apertures mounted between said hollow bodies and said cathode means and said anode means respectively.

4. An electron discharge tube for producing short electromagnetic waves comprising an ex hausted envelope, cathode means within said envelope for emitting electrons, anode means within said envelope for intercepting said electrons, negative electrodes adjacent to said cathode means to collect the emitted electrons to form an electron beam, hollow metal bodies each having apertures and being connected to a lead wire and disposed between said cathodemeans and anode means in the path of said electrons, and accelerating electrodes provided with apertures mounted between said hollow bodies and said cathode.

said envelope for intercepting said electrons, a

negative electrode adjacent to said cathode to collect the emitted electrons to form an electron beam, hollow metal bodies each having apertures,

and being connected to a leadwire and disposed between said cathode means and anode means in thepath of said electrons, .and accelerating electrodes provided with apertures mounted between said hollow bodies and said cathode means and said anodemeans respectively, said apertures in said hollow metal bodies and in said accelerating electrodes being of a shape corresponding to the cross section of the electron beam.

.7. An electron discharge tube for producing short electromagnetic waves comprising an ex-- hausted envelope, cathode means within said envelope for emitting electrons, anode means within said envelope for intercepting said electrons, said anode means being slantingly mounted to the path of the electrons, auxiliary anode means for intercepting electrons having a low velocity,

negative electrodes adjacent to said cathode. to. collect the emitted electrons to form an electron beam, hollow metal bodies each having apertures and being connected to a lead wire and disposed between said cathode means and anode means in the path of ,saidelectrons, and accelerating electrodes each provided with an aperture mounted between said hollow bodies and said. cathode-- means and said anode means respectively, said apertures in said hollow metal bodies and in said accelerating electrodes being of a shape corresponding to the cross section of the electron aperture in said anode, and brealnng and intercepting electrodes beyond said anode comprising a plurality of parallel insulated plates each having an aperture and mounted with said apertures? aligned with the aperture in said anode to be in the path of said electron beam, said plates being inclined to the path of said beam beyond said anode.

9. A short wave electron discharge tube comprising anevacuated envelopeenclosing means including an electron emitting cathode for forming an electron discharge fromsaid cathode into an electron beam, electron intercepting electrodes comprising a plurality of insulated metal plates inclined to the direction of and mounted to intercept the electron beam, spaced accelerating electrodes between said means and said intercepting electrodes'and having aligned apertures in the path of the electron beam, a hollow metal body connected to a lead wire and disposed between and with its ends near said accelerating electrodes and having apertures aligned with the apertures of said accelerating electrodes, said apertures in said hollow metal body and in said accelerating electrodes being of a shape corresponding to the cross-section of the electron beam.

10. A short wave electron discharge tube as defined in claim 9 in which the hollow body and the accelerating electrodes have at the apertures tubular projections surrounding the apertures.

11. A short wave electron discharge tube as defined in claim 9 in which the intercepting electrodes are parallel and have apertures corresponding in shape to. the cross-section of the electron beam and disposed in the path of the electron beam. 7

12. An electron discharge device including an evacuated envelope containing a cathode for supplying electrons, means tor forming said electrons into a beam; a collector electrode for receiving electrons in said beam and velocity mod-' ulating means for accelerating and decelerating said electrons, said velocity modulating means including a hollow tubular conducting member adapted to have alternating potentials of high frequenciesapplied thereto during operation of I said electron discharge device and an apertured electrode adjacent each end of said hollow tubular conducting member and positioned between said hollow tubular conducting member and all for subjecting said beam to a high frequency field before entering said hollow electrode and after leaving said hollow electrode, and a second apertured electrode between said hollow electrode and said collector electrode. 5 14. An electron discharge device including an evacuated envelope having a'gaseous atmosphere therein and containing a cathode for supplying electrons. means for iorming said electrons-into a beam, a collector electrode for receiv ng electrons in said beam and velocity modulating means for accelerating and decelerating said electrons, said means including a hollow tubular member adapted to have alternating potentials of high frequency applied thereto during operating of said electron discharge device, and an apertured electrode adjacent each end of said hollow electrode and positioned between said hollow electrode and all of the other "electrodes within said envelope. g

15. A short wave electron discharge device comprisingan evacuated envelope enclosing a velocity modulating means comprising a hollow metal I body, means adjacent one end of said-hollow metal body and including an electron emitting g5 .cathode for forming the electron discharge from said cathode into an electron beam directed through said hollow metal body, and acollector adjacent the other end of said hollow metal body in the path or the electron beam which is to be 30 passed through said hollowlmetal body, and an apertured electrode adjacent each end of the hollow metal body and each having an aperture in the path of the electron beam through said hollow metal body, said collector being inclined 35 to-the path of the electron beam through the apertured electrodes; 7

16. An electron discharge deviceincluding an evacuated envelope containing a cathode for supplying electrons, means for forming said elec- 4o trons into a beam, a collector electrode for receiving electrons in said beam and velocity modulating means for accelerating and decelerating said electrons, said means including a. hollow tubular conducting member adapted to have al- 5 ternating potentials of high frequency applied thereto during operation of said electron discharge device, and an apertured electrode adjacent each end of said hollow. tubular conducting member and positioned between said hollow tubular con- 80 ducting member and all of the other electrodes within said envelope.

17. An electron discharge tube for use at high frequencies including a cathode for supplying electrons, means for forming said electrons into 65 said electrode means comprisinga hollow body 60 for providing a field free space through which the beam passes after being subjected to said high frequency alternating field, and electrode means between said collector electrode and-said. hollow body for abstracting energy from said beam after 08 its passage through the field free space and before reaching said collector electrode.

18. An electron discharge tube for'use at high frequencies including a cathode for supplying electrons, means for forming said electrons into 7 c a beam and a collector electrode for said beam, velocity modulating means between said cathode and collector electrode including an apertured electrode and a hollow electrode for applying a high frequency alternating field to said beam, 78

said hollow electrode providing a'field free space through which the beam passes after being subjected to said high frequency alternating field; and electrodemeans including said hollow electrode and a second apertured electrode for abstracting energy from said beam after its passage through the field free space and before reaching said collector electrode.

19. An electron discharge tube for use at high 10 frequencies including a cathode for supplying electrons, means for forming said electrons into a beam, a collector electrode for said beam, a hollow electrode positioned between said cathode and collector electrode throughwhich said beam is directed, a control electrode between said cathode and hollow electrode for modulating the beam of electrons, an apertured electrode positioned between said-control electrode and said hollow electrode and a second apertured electrode between said hollow electrode and collector electrode, said hollow electrode and said first apertured electrode defining a high frequency field space through which said beam is to-pass before entering said hollow electrode, and said hollow electrode and said second apertured electrode defining a second high frequency ,field space through which said beam is to pass after leaving said hollow electrode. v

20. An electrondischarge device for producing 30 short electromagnetic waves, including an evacuated envelope, cathode means within said envelope for supplying electrons in oppositely disposed beams, anode'means within said envelope for intercepting said beams of electrons, a hollow metal body'disposed in each beam path between said cathode means and said anode means, and accelerating electrodes provided with apertures mounted between each of said hollow metal bod-q ies and said cathode means and said anode.

40 means respectively.

21. A short wave electron discharge tube in cluding an evacuated envelope containing a hol-" low metal body, means adjacent one endof said hollow metal body and including an electron emitting cathode for forming said electron discharge from said cathode into an electron beam directed through said hollow metal body, a collector electrodemounted adjacent the other end of said hollow. metal body in the path of the 22. An electron discharge device for use at high frequencies having a cathode for supplying electrons, means for forming said electrons into a beam and a collector electrode for said beam, a first apertured electrode adjacent said cathode, conductivemeans surrounding the electron path and located between said first apertured electrode and said collector electrode, said conductive means having a surface next adjacent said first apertured electrode defining therewith a high frequencyfield space, and a second apertured electrode between said conductive means and said collector electrode.

23. An electron discharge device for use at high frequencies including a cathode for supplying electrons, means for forming said electrons into a beam, and a collector electrode forsaid beam, a pair of apertured members positioned between the cathode and the collector through which said beam of electrons is directed, and a velocity modulating member surrounding the beam between said apertured electrodes for modulating the beam.

' 24. An electron discharge device for use at high frequencies and including a, cathode for supplying electrons, means for forming said electrons into a beam, and a collector electrode for said beam, a, firstelectrode-meansbetween said cathode and collector electrode for applying independently of said cathode a high frequency alternating field to said beam for velocity modulating the beam,

and a second electrode means between said first electrode means and said collector electrode for abstracting energy from said beam after the ap- CERTIFICATE or CORRECTION. Patent No.- 2,25 ,L 97. mar-ch1 [191;1.

- OS KAR HEIL.

It is hereby certified that error appears in the printed specification of the above nunfbered pater 1t requiring correction as follows Pagel, first column, line 9, for "0i! an" read -of an-- and second column, line'?, for '.'dwell,"' The" read- 'dwell" The -5; line 29, for "'diffeer'nt"-read --different; page}, first COlUJliIl, line 65', after "arrangement" insertthe following paragraph- Figure l0 is a diagrammatic representation of a modification of an electron discharge device made according Y to my invention and its relative 'potentials;

line 65-66, for "a'djecent" rea'd "adjacent"; and second column, line 56, for "ocil-lating" readioscillating page 14, first column, line 20, for "later, having" read "later. Having--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. I v

' Signed and sealed this ra day of June, A.- D. 1.9m.

. Henry- Van Am'sdale (Seal) Acting Commi ssi oner of Patent s CERTIFICATE or CORRECTION. Patent No.- 2325 197. march'18, 1'9u1.

- OS KAR HEIL. 4

It is hereby eertified that error appears in the printed specification of the above numbered patent requirin'g correction as follow s Page 1, first column, line 9, for "or an" read --of anand second column, line 7, for '.'dwell;"- The" read- 'dweil". The-f; line 29, for '"diff eer'nfl-read different--; page}, first column, line 65', after "arrangement? insert the following paragraph I I v Fign re lO is a diagrammatic representation of a modification of an electron discharge device made according to my invention and its relative 'po ten tials line 65-66, for "adjacent" read "adjacent"; and second column, 1ine'56 for "ocil'lating" readi osoillating page )4 first-(column, line 20, for "laterQhaving" read -,1a-ter'. Having-; and that'the said-Letters Patent shouldbe read with this correction therein that the same may conform to .the record of the case in the Patent Office.

' signed and sealed this 51-21 day of Jane, A.- D. 1.9!;1.

. Henry- Van Ar'edale (Seal) I Acting Commi ssi oner of Patent s.

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