US1719699A - Thermionic tube - Google Patents

Description

J ly 929 'w. E. E. HABANN 1.719.699

' THERMIONIC TUBE Filed June :15. 1922 2 Sheets-Sheet 1 Fig.1. 2 4 .2. 4 T

iii

Patented July 2, 1929.

UNITED. STATES PATENT, OFFICE.

THERMIONIC TUBE.

Application filed June .15, 1922, Serial No. 568,551,. and in Germany June-24, 1921.

Applications have been filed in Germany partly on 24th June 1921 and part1 on 14th October 1921, Italy partly on 12th ay 1922 and partly on 13th May 1922, France 8th May 1922, Switzerland 10th May 1922, the Netherlandsllth May 1922, Austria and Sweden 12th May 1922, Hungary 15th Ma 1922, Belgum 17th May 1922 and Denmar 20th May 22. This invention relates to a thermionic tube, in which the path travelled by the electrons between thesource of the electrons (filament) and the anode, is acted on in such a manner by 'at least one constant magnetic field and by at least one constant electric field, which opposes the magnetic field as regards its actron on the free electrons, that the path, over which the discharge takes place acts as a negative resistance. The auxiliary field may be produced by an auxiliary flow of electrons, which is generated by an auxiliary discharge crossing the main discharge and passing between a filament and an anode. A thermionic tube of this type isadapted to be used for all purposes, w ere it is of advanta e, for the path, over which the discharge ta lies'place, to have a negative resistance, for instance for roducing, reinforcing, or amplifying, recti ying, ctc., alternating currents and oscillations.

The accompanying drawing shows a constructional example of the invention.

Figure 1 is a front elevation of the therniionic tube,

Figure 2 a side elevation and Figure 3 a section through the tube on the line 3-3 of Fi ure 2.

Figure 4 is adiagram of connections of the thermionic tube shown in Figures 1-3, for use as a generator for oscillations.

Figures 5 and 6 are diagrams of two mod1- fied systems of connections according to the invention. The thermionic tube according to Figs.

1-3, which is evacuated to such an extent that no perceptible ionization, that is, no glow discharge occurs at the source of the electrons, contains the usual filament 1 and a plateshaped anode 2; In order to facilitate the emergence from the filament, the lattercan be surrounded by a grid 3 of a well-known ty e, which is connected up to a low posltlve vo tage, Substantially parallel to the path, over which the discharge takes place, there is r a metal surface 4, which serves the purpose of producing a constant electric field. In

- oscillations.

the example shown this metal surface 4 ('ondirection of motion of the electrons from the filament 1 to the anode 2. They act in opposltion to one another with respect to. the moving electrons. To obtain'this effect it is naturally only necessary for the two fields to have such a relative position that the forces exerted by both on the electrons form a resultant at right angles to the path, over which the dischar e takes place.

Both the electric field and the magnetic field exert under certain conditions a deflecting action on the electrons movingin the path, over which the discharge takes place. Each of these deflections itself constitutes a lengthening of the pathoithe electrons. On the tube being at into operation, it is so adjusted, that tie two fields balance each other, in other'words, that the path of the electrons substantially follows a-straight line between the filament and the anode.

Figure 4 shows a diagram of connections, where the tube is usedfas a generator for The oscillatory circuit 6 lies between the cathodel and'the anode 2. The high voltage battryy7, of about 20.0 volts, is conneeted'up in the branch circuit between the oscillatory circuit 6- and the anode 2. The electric field of the plate 4 is produced by a battery 8 of about 100 volts, the other pole of which is connected to the cathode 1. The

electromagnet 5 is supplied by a constant current of any kind, which may be taken from the battery 9 of the filament.

The electron-0.11rrcnt having a velocity n 'will thus be subjected to the action of a constant electric field F, and a constant magnetic field H. Owing to the'oppositc adj ustment, onetorce will deflect the electrons to one side. and the other force to the other side. The deflection due to the electric force is proportional to g and that due to the magnetic force is proportional to Together with the increasin voltage, which increases 0, the deflection no to the magnetic force will predominate, since this is only inversely proportional to the first power of '0, while the deflection due to the electric field is inversely proportional to the second power of 2:. Therefore the electrons will be deflected from their paths with the increase of voltage; less electrons will arrive at the anode,

and the conditions prior to the increase ofvoltage are destroyed, whereby the anode current decreases when the voltage increases. This is the characteristic of a thermionic tube having a negative resistance, or a falling characteristic.

.The said increase in voltage is efl'ected periodically during very short periods of time by the oscillatory circuit 6 cooperating with the anode current as is well known.

The increase in the length of the path of the electrons causes a drop in the strength of'the field of the anode as is well known. The increase of the anode voltage had of course previously caused an increase in the strength of field of the anode. The tube can be easily constructed in such a manner that the reduction in the strength of field of the anode, due to the deflection of the electrons, shall be. greater than the previous increase in the strength of field, due to the increase in the voltage. The protective grid 3, which is connected for instance to a battery 10 of from 10 to 30 volts, does its share in bringing about the desired effect.

Besides being used as a generator for oscillations, the thermionic tube can also be used as an amplifier. In this case the oscillatory circuit 6 is replaced by the positive resistance to be counteracted, for instance, a telephone line. If the amplified currents are to be connected to a grid, either the grid 3, already mentioned, or a controlling member located next to the said grid and extending into the path of the discharge can be used. The amplification in this case exceeds considerably that of the normal thermionicttubes having three electrodes, as the positive resistance of the telephone, which takes the place of the oscillatory circuit 6, is compensated by the negative resistance of the tube.

If, in place of the microphone currents high frequency receiving currents are connected to the grid or controlling member, the thermionic tube will at the same time act as a rectifier. If an oscillatory circuit is'connected up in series with the telephone, it will act as an ultraaudion.

In the modified systems shown in Figures 5 and 6 the action of the thermionic tube is further improved therein that the electric field, which in the constructional form shown in Figures 1-3 is a static field, is converted into a kinetic field. For this purpose the auxiliary field is produced by an auxiliary flow of electrons, which is generated by an auxiliary discharge crossing the main discharge and passing between a filament and an anode. The lateral electrons thus generated and flying at right angles to the main flow of electrons, force .the former ones out of their path, with the result that in this way the conditions for the production of a negative characteristic are more energetically obtained.

As in the constructions described with reference to Figures 1-3 discharge takes place between the cathode 1 and the anode 2. The former can be embraced by a protective grid 3. The magnetic field is generated by an clectromagnet coil 5 which is indicated by a dot 'and dash circle.

According to-the modifications shown in Figures 5 and 6 opposite the lateral plate 4, which here represents the anode of an auxiliary discharge, a second filament 14 is mounted between these two electrodes, there is a flow of electrons which crosses that of the main discharge between 1 and 2. The impact of these lateral electrons depends on their number and their velocity. The latter can be varied at will by altering the voltage between the auxiliary electrodes. The number of auxiliaryelectrons can be increased by varying the dimensions of the filament of the auxiliary cathode. The auxiliary cathode 14 is preferably also surrounded by a protective grid 15.'

Fig. 5 shows an arrangement for the generation of oscillations, assuming for the time being the telephone 18 to be short-circuited. The filament 1, which is heated b the battery 9, is connected to the anode 2 yway of the oscillatory circuit 6 and the high voltage battery 7. The oscillatory circuit 6 is coupled to the antenna 19. The auxiliary cathode 14,

which is heated by the battery 17, is connected to the auxiliary anode 4 by Way of the battery 8. The protective grid 3 is positively charged by a battery 10 and the protective grid 15 by a battery 16. The generator acts in exactly the same manner as that described with reference to Figures 1-3, except that the conditions of the negative characteristic are, in consequence of the more pronounced action of the electric field, formed by the flow of the auxiliary electrons.

On the telephone 18 being connected up, the arrangement acts as a receiver for undamped oscillations arriving in the antenna, that is, as a heterodyne receiver.

The main anode 2 is preferably edge-on to the direction of the corresponding discharge path, which results in the advantage, that the two electron paths out each other in a much more defined line.

The arrangement shown in Fig. 6 has proved particularly useful. In this arrange ment the antenna 19 is not coupled to the oscillatory circuit 6, but to a coil 20, one end of which is connected to a condenser 21. A high resistance 22 is in parallel with the latter. The coil 20 is on the one hand connected directly either to a. controlling grid of the main discharge lying either before or behind the protective grid 3, or to a controlling grid of the auxiliary discharge and is on the other hand connected by way of the condenser 21 to the corresponding cathode. -The controlling grids at the main discharge are marked 23 and 24, while those of the auxiliary discharge are marked 25 and 26. Thus the terminal W of the coil 20 is connected to the point R andthe terminal V to the points H or P or the terminal \V to A and the terminal V to B or C.

In one Case the auxiliary electrons and in the other case the main electrons are controlled andthe undamped oscillations are modulated to suit the speaking.

I claim:

1. Means for producing negative resistance, comprising a tube having an anode and a cathode between which a stream of electrons may pass, and ineansfor producing adjacent the'path ot' the electrons a constant electric field, and means for producing an electromagnetic field, said fields to be perpendicular to one another and to the direction of the electron stream, said fields being poled and proportional to equally oppose one another at a certain potential on the anode, and to unequally oppose one another at higher potentials on the anode, to deflect the electron stream there y decreasing the number of electrons that reach the anode for producing the desired negative resistance characteristic.

2. Means for producing negativeresistance, comprising a tube having an anode and the static field being of such relative value asto have substantially no deflecting eflect upon the electron stream at a certain potential on the anode, but having an unequal deflecting eflect upon said stream at higher potentials on the anode, to bend the electron stream away from its path, and reduce the current accordingly.

3. Means for producing negative resistance characteristic comprising a tube, a cathode and an anode in the tube between which a stream of electrons may pass, a grid positioned in the path of said stream of electrons, means comprising an electrode positioned laterally of said path to produce adjacent thereto a constant electro-static field, transverse in direction to said electron stream, means including a magnet to produce adjacent said path a. constant magnetic field, transverse in direction to said electron stream, said electromagnetic field equally opposing the action of said electro-static field on the electron stream at a certaiirpotential on the anode

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