US2071923A - Electron discharge device - Google Patents

Description

Feb. 23, 1937; s. G. FRANTZ ELECTRON DISCHARGE DEVICE Original Filed May 22, 1930 4 Sheets-Sheet l OFOOOWNO.

*AOOOOQO 34 WOOOGO INVENTOR I SAMUE G- FRANTZ BY g ATTORNEY ,1 3 s. G. FRANTZ ELECTRON DISCHARGE DEVICE Original Filed May 22, 1930 4 Sheets-Sheet; 2

lLl lll ooAWoo/ooooooo I'Ll OOOO OOOOOOOO I'll m? ET INVENTOR SAMUEL 'GVFBANTZ- v ATTORNEY' Feb. 23, 1937;

s. GJFRANTZ ELECTRON DISCHARGE DEVICE 4 Sheets-Sheet 3 Original Filed May 22, 193i) .7 W Rumbas QQ O KERQuQ Q 0 SAMUEL GRANZ BY fig, MW

ATTORNEY Feb. 23, 1937; s FRANTZ 2,071 ,923

I ELECTRON DISCHARGE DEVICE Original Filed May 22, 1 930 4 Sheets-Sheet 4 iNVENTOR SAMUE G. ANTZ ATTORNEY Patented Feb. 23, 1937 UNITED STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE of Delaware Original application May 22, 1930, Serial No.

454,533, now Patent No. 2,013,093.

Divided and this application September 20, 1932, Serial No.

7 Claims.

This application is a division of U. S. Patent application Serial No. 454,533, filed May 22, 1930, which issued as Patent 2,013,093, Sept. 3, 1935, for Electron discharge devices.

5 The present invention relates to electron discharge devices and more particularly to a methd of controlling the flow of electrons.

The invention comprises a novel method of, and means for, controlling the flow of electrons 10 in an electron discharge device, and depends upon the proposition that current flowing through a conductor produces a magnetic field around the conductor, and also that an electron in motion is similar to current flow in a conductor. If a 15 conductor is positioned in an electron discharge device and carries current, the magnetic field around the conductor will tend to deflect or control the electronic flow in the discharge device. These phenomena are utilized in the present in- 20 vention in several forms; for example, current is made to flow through the grid of a thermionic valve, and the magnetic field produced by this current is utilized to deflect electrons travelling from the cathode toward the anode. The necessi- 25 ty for negative grid bias for the grid is thereby eliminated.

In another aspect of the invention, these phenomena relating to magnetic fields may be utilized for the reduction of heat losses in thermi- 30 onic valves and high power rectifiers, and in avoiding the effect, often objectionable, of secondary emission from the anode or electron collector. In my arrangement, an auxliary electrode is positioned close to the plate or elec- 35 tron collector, and current is passed through this aux liary electrode; at the same time a high positive potential is supplied to this auxiliary electrode to accelerate the flow of electrons from the cathode toward the auxiliary electrode. The

0 magnetic field created by the current flowing in the auxiliary electrode will deflect the electronic flow to an extent sufficient to repel the electrons from the auxiliary electrode, and at the same time the high velocity of the electrons accelerated by the high positive potential of the auxiliary electrode will be sufficient to bring the electrons to the anode or electron collector.

Other aspects of the invention will appear fur- O ther in the specification.

The invention will be more clearly understood with the aid of the accompanying drawings.

Figure 1 represents a schematic showing of a simple form of my invention as applied to the 55 ordinary three electrode vacuum tube.

Figure 2 represents a schematic showing of another form of my invention, in which an additional electrode is employed to accelerate the electrons.

Figure 3 is a schematic showing of a modification of my invention, in which the magnetic field for deflecting the electrons is produced by a solenoid external to the tube.

Figure 4 shows another view of the structure of Figure 3.

Figure 5 represents the schematic showing of another form of my invention, in which the magnetic field for deflecting the electrons is produeed by current flowing in the central electrode of the electron discharge device.

Figure 6 shows another view of the structure illustrated in Figure 5.

Figure 7 shows another form of my invention in which the accelerating electrode itself carries the current for producing the magnetic field which deflects the electrons.

Figure 8 shows another view of the structure illustrated in Figure '7.

Figure 9 shows schematically another form of my invention similar to that of Figures 7 and 8 except that in Figure 9 the accelerating electrode which carries the current is positioned within the anode or electron collector.

Figure 10 is another View of the structure illustrated in Figure 9.

Figure 11 shows schematically another modification in which the accelerating electrode which carries the deflecting current is positioned entirely around the anode or electron collector and takes the form of a flattened tube in cross section.

Figure 12 shows another view of the structure illustrated in Figure 11.

Figure 13 shows my invention as applied to a half wave rectifier circuit.

Figure 14 shows a schematic wiring diagram of my invention as applied toa three phase rectifier circuit.

Figure 15 shows diagrammatically the wiring diagram of a tube which contains an accelerating electrode according to my invention.

Figure 16 shows schematically a wiring diagram of another form of half wave rectifier constructed according to my invention.

Figure 17 shows a schematic wiring diagram of another form of rectifier constructed according to my invention.

Figure 18 shows the schematic wiring diagram trons flowing from the cathode.

of an amplifier constructed according to my invention.

Figure 19 shows the schematic wiring diagram of another form of amplifier constructed according to my invention.

Figure 20 shows the schematic wiring diagram of still another form of half-wave rectifier constructed according to my invention.

Figure 21 shows schematically an indirectlyheated vacuum tube according to my invention.

Figure 22 shows a tube similar to that of Figure 20 wherein the accelerating electrode is positioned within the tube.

In ordinary three electrode tubes, the three electrodes comprise a hot electron-emitter or cathode, a cold electron-collector or anode, and an input or control electrode known as the grid. When the cathode is heated sufiiciently and when a proper potential difference is applied between the anode and the cathode, electrons will fiow from the cathode to the anode, as is well known. The control electrode or grid is impressed with the control voltages to affect the flow of electrons from the cathode to the anode, or in other words, to control the flow of current from the anode to the cathode. Since the control electrode is usually positioned between the cathode and the anode, and since the control grid would normally be positive sometimes with respect to the cathode, some of the electrons flowing from the cathode to the anode will be attracted to the control electrode. This fiow of electrons to and through the control electrode has given rise to several difficulties, and many attempts have been made to eliminate or reduce this fiow. The common method is to apply to the control grid a potential or bias which is negative with respect to the cathode. This tends to reduce or eliminate the attraction which the control grid has for the elec- This, however, does not entirely eliminate the fiow of electrons to and through the grid, because notwithstanding this negative bias, the fluctuations in control voltages make the control electrode more positive at times than the negative biasing potential applied to it, and this reduces or neutralizes the repulsion which the control grid should exert on the electrons. Too much grid bias will stop operation of the tube. Moreover, the position of the control grid between the cathode and the anode subjects the control grid to bombardment by the electrons, and many of them enter the control electrode.

I have found that I can exert a greater repulsion on. the electrons tending to enter the grid than has heretofore been accomplished by the negative grid biasing potential.

A simple form of my apparatus is illustrated in Figure 1 which shows a three electrode tube adapted to the purposes of my invention. In this figure, the cathode or filament l is shown as a straight wire, although it is obvious that it may be of the hairpin type or cylindrical type of filament or the indirectly heated cathode type. Surrounding the cathode I is the control electrode or grid 2, which is here shown schematically as a helix, although it may have other forms, the main requisite being that the elements of the grid be spaced apart to permit the electrons to pass therethrough on their way to the electron collector or anode 3. This anode is shown as a cylinder concentric with the cathode I and the grid 2, although it is apparent that it may have other forms, and may comprise a plate, a wire, or

any combination of these. Enclosing the whole may be an envelope, not shown, of glass or metal.

During operation of the tube, the cathode l is heated to emit electrons, and the potential of the anode 3 is such as to attract the electrons. The grid 2 is impressed with the signal voltages to control the number of electrons passing through to the anode 3. This is the usual process of operating the tube. In addition, I pass a current through the grid 2 during the operation of the tube. As is well known, a wire which carries current produces lines of force around. it, the direction of which may be determined by the so called right hand rule. The control grid 2, therefore, will at all times during operation have a magnetic field which will have a direction perpendicular to the plane of the figure. As the electrons approach the grid 2 on their Way to the anode 3 which attracts them, the magnetic field produced by the current in the grid 2 will exert a repelling effect on the electrons. The electrons will consequently be induced to take the path shown by the broken line in the figure. The path will approximate the shape of a spiral, the degree of which will depend on the voltage difference between the cathode and the anode and on the force of the magnetic field produced by the guard current in the grid 2. The magnetic field and the current which produces it will not affect the electron emitting tendencies of the cathode, but on the other hand the input voltages on the control electrode 2 willact in the normal manner to control the fiow of electrons, and the anode will act in the usual manner to attract the electrons in its vicinity. The grid 2, however, will not receive electrons because the local magnetic field in the immediate vicinity of the grid wires will repel the electrons. My device, therefore, will be such as to eliminate or substantially reduce the flow of electrons in the control grid and this will be accomplished without the aid of the grid biasing potential.

Figure 2 shows another form of my invention in which an additional electrode is employed to accelerate the electrons from the cathode to the anode. In this figure, the cathode i is shown schematically as a cylinder, although as pointed out in connection with Figure 1, it may have other forms and shapes. Surrounding the cathode l is the control grid 2, and surrounding the control grid 2 is the electron collector or anode 3. Positioned between the grid 2 and the anode 3 is an additional electrode 4 which acts to accelerate the fiow of electrons from the cathode l to the anode 3. The electrode 4 is given a high potential to attract the electrons from the cathode l and this potential is so high that the momentum attained by the electrons will be sufficient to cause them to pass through the accelerating electrode 4 and strike the anode 3, even though the potential of the anode be less than that of the accelerating electrode 4%. This will permit the use of lower plate potentials. In addition, the accelerating electrode i may carry a current which induces a magnetic field to prevent the electrons from entering it. If desired, the control grid 2 may also have a current traversing it to prevent any of the electrons from entering it, thus both the grid 2 and the accelerating electrode 4 may carry currents.

In the ordinary tube, the anode may be said to have two functions. The first is to provide the necessary accelerating electro-static field by acting as the high potential plate of a condenser,

the other plate being the cathode. The second function is to act as the receiving electrode which collects the electrons so that they may be removed from the tube as current through a wire provided for the purpose. In the ordinary tube, the combining of these two functions results in the following two serious disadvantages: The anode is bombarded by high velocity electrons accelerated by the high potential of the anode, and the kinetic energy of these electrons appears in the anode as heat. In power tubes the limit of power capacity is determined by the ability of the anode to dissipate this heat. Among the methods adopted to dissipate this heat are watercooling, air-cooling, oil-cooling, large surface for the anode, and others. The second undesirable result is the electrical power loss in the circuit, which loss is equal to EI. That is, some of the power which might ideally appear in the output circuit is lost so far as useful work is concerned. The power loss, EI, is the potential difference E between the cathode and the anode, times the electron current I between the cathode and the anode. This energy represents the kinetic energy given to the electrons which finally appears in the anode in the form of heat and is entirely kept at a very high potential; in fact, it may be kept at a much lower potential than the auxiliary accelerating electrode, and acts to receive most of the electrons which have been discharged from the cathode. Instead of passing a current through the accelerating auxiliary electrode to prevent it from receiving electrons emitted by the cathode, the same purpose may be achieved by a suitable geometrical design of the accelerating electrode and the other elements of the tube. In such a case, the electrons are given such a path as to avoid directly striking the auxiliarly electrode 4, although the electro-static potential of this accelerating electrode acts to attract the electrons from the cathode.

Figures 3 and 4 illustrate one form of my device in which the accelerating electrode does not carry current. Here the cathode I is illustrated as a straight filament, although it is obvious that a hairpin or helical filament or indirectly heated cathode may be employed. The anode or electron receiving electrode 3 is shown here diagrammatically as straight vanes, although it is obvious that other forms may be used, and in fact it is necessary only that the anode be appropriately apertured, as will hereafter appear. The accelerating electrode 4 is in the form of a cylinder surrounding the anode 3, although it is apparent that the accelerating electrode 4 may have other forms to suit the appropriate design. In this modification, the external solenoid 5 surrounding the accelerating electrode 4 is used to produce the magnetic field, which in this instance will act on the electrons in the direction shown by the arrows. The electrons emitted by the cathode i will be directed toward the accelerating electrode 4 on account of the latters high potential, but the magnetic field produced by the external solenoid 5 will be just sufiicient to deflect the electrons so that they strike the face of the anode or electron collecting electrode 3.

The path of the electrons is shown by the broken lines in Figures 3 and 4.

In another modification illustrated in Figures 5 and 6, the cathode l is utilized as the generator of the magnetic field by passing current through it or an adjacent wire, and the magnetic field will deflect the electrons so that they strike the anode 3 rather than the accelerating electrode 4. The path of the electrons is illustrated by the broken lines in Figures 5 and 6.

In another modification of my invention, the accelerating electrode itself carries current which produces all or part of the magnetic field to deflect the electrons. One form of this modification is shown in Figures 7 and 8. Here i is the cathode, as before; 4 is the high potential accelerating electrode; and 3 is the anode or electron receiving electrode. The anode 3 and the accelerating electrode 4 are given the form of intermeshing helices of the same diameter and concentrically positioned about the cathode l. The accelerating electrode 4 is made to carry a current counter-clockwise (as shown in Figure 7), and the anode 3 is made to carry current clockwise, the current in 4 being greater than the current in 3. The magnetic field between the cathode l and the intermeshing helices will therefore be up (as shown in Figure 8). As the electrons leave the cathode l and flow toward the anode 3, they will receive a tangential component of velocity in a counter-clockwise direction, substantially horizontal as viewed in Figure 8, until they approach the helices. Near the wires 4 and 3, the magnetic field will exert a vertical force on the electrons having counter-clockwise movement and tend to move them away from 4 toward 3, as shown by the broken lines in Figure 8. The electrode 4 will thereby act only as an accelerating electrode, without receiving any of the electrons which it is desired that the anode 3 receive.

In another form of this modification, illustrated in Figures 9 and 10, the device is made in the form of the usual three electrode tube, with the addition of a helix 4 which acts as the accelerating electrode. As shown, this helix 4 is positioned relatively close to the anode 3. Current is passed through the accelerating electrode 4, as above discussed, and the electrons in their path from the cathode l to the anode 3 will receive a counter-clockwise velocity as shown in Figure 9. The current flow in the accelerating electrode Q is counter-clockwise, as before, and the magnetic field induced by this current will tend to deflect the electrons in their path before they reach the helix 4 as shown in Figure 10. This deflection will be sufiicient to cause the electrons to pass in through the interstices of the helix 4 and collect on the anode 3. As is obvious, the anode 3 may be in other forms than a cylinder and may be in the form of a flattened oval or a flat plate, the accelerating electrode 4 being correspondingly formed to be positioned close to the anode 3.

Since the anode 3 may be at a potential only slightly above that of the cathode l, contradistinction to the very high potentials used in the present tubes, the kinetic energy of the received electrons in my device is small on account of the relatively low velocity of the electrons as they strike the anode 3. The heating of the anode is therefore small and the power capacity of my tube will be relatively great. At the same time the power loss, which as above discussed is equal to El, is small, and my tube is therefore highly efiicient.

Figures 11 and 12 illustrate another modifica tion of my invention in which the accelerating electrode 4 is given the form of a hollow member surrounding the anode 3. Current is sent up through the accelerating electrode 4 within the anode 3 as shown by the arrows in Figure 12, and current is sent down through the cathode I. The magnetic field resulting from the current in the accelerating electrode 4 and the current in the cathode I will be such as to deflect the electrons away from the wires of the accelerating electrode 4 just before they reach the accelerating electrode 4 on their way to the anode 3. In any of these constructions a control grid 2 may be added outside the cathode I.

Figure 13 represents a rectifier circuit in which a half-wave tube is used, that is, a tube which rectifies one half of the cycle. The anode is shown at 3. The cathode I is energized from the source i I. At 4 is the accelerating electrode through which is passed a current from the source 8. A coil 9 may produce an auxiliary magnetic field to help deflect the electrons from the accelerating electrode. This coil 9 may be either within or without the tube. The battery I8 produces the high potential of the accelerating elec trode 4. My invention is peculiarly applicable to rectifier circuits because it increases the power capacity of the tube, reduces heating of the anode, and permits lower operating potential of the anode, as previously set forth.

Figure 14 shows another modification of my invention which consists of a rectifier circuit for a three phase line. In this figure a tube having three anodes is used. A three phase transformer I is connected to the alternating current lines and is connected to the anodes 3. The cathode I is energized by the source of current Ii, as in the rectifier circuit previously described. An accelerating electrode i is positioned about the cathode i and between the cathode I and .the anode 3 and serves as previously set forth. A coil 9 for producing an additional magnetic field may be positioned within the tube or without the tube as set forth previously.

Figures 15 illustrates the tube operated in a circuit according to my invention. The tube contains a cathode l, suitably heated, a screen electrode l maintained at a comparatively high potential by the battery I8 to act as an accelerating electrode, and an anode 3, which is at a lower potential than the accelerating electrode 4. When this tube is used as an amplifier, it may have a control grid 2. magnetic fields are applied and the open construction of the accelerating electrode 4 allows a certain proportion of the electrons to go through and strike the anode 3. The electro-static field between the accelerating electrode 4 and the anode 3 being a retarding one, the electrons will strike the anode 3 at a lower velocity than if the anode 3 were at a high potential. It will therefore be seen that the heating of the anode 3 due to the bombardment of the electrons will be reduced, and that the EI power lost between the cathode and the anode will also be reduced.

Figure 16 shows another form of my halfwave rectifier circuit. The cathode I is energized by a battery II, and surrounding the cathode I is a helical auxiliary electrode 4 which is given. a high potential by means of the battery I8; As previously discussed, the accelerating electrode 4 will attract the electrons from the cathode I toward the anodev 3.

Figure 17 shows another rectifier circuit. In this. modification, the accelerating electrode, 4

In its simplest form, no.

carries current which is supplied to it by means of the transformer 40 from a source of alternating current potential, preferably that of the alternating current to be rectified. If desired, battery 8 may supply direct current to the electrode 4.

Figure 18 shows a circuit in which my tube is employed as an amplifier. The transformer 40 transfers the incoming signal to the tube. The accelerating electrode 4 is tapped to one of the windings of the secondary of the transformer 40 and consequently carries current to produce the magnetic field. The accelerating electrode 4 is made to act as the control electrode at the same time. If desired, battery 8 may supply direct current to the electrode 4.

Figure 19 shows another form of amplifier circuit. Here the accelerating electrode 4 is supplied with direct current from the cell or battery 8. The control grid is shown at 2.

Figure 20 shows another form of circuit for a half wave rectifier. In this modification, the guard current and the accelerating potential are supplied by means of a transformer 50 from the source of alternating current potential which is to be rectified.

Figure 21 shows one form of my tube in which the solenoid 5 is placed outside the glass envelope Bil. The control grid 2 has the input potential impressed thereon and a guard current is passed through it in the same direction as that in the solenoid 5.

Figure 22 shows another form of my tube in which the accelerating electrode 4 is positioned within the anode 3. A guard current may be passed through the accelerating electrode 4, or through the control grid 2, or through both the control grid 2 and the accelerating electrode 4. Here, as in Figure 21, the various electrodes may have other forms and shapes than those illustrated.

Not only does my invention reduce the power loss and the heating of the tube but it also reduces the mechanical disintegration of the anode due to the high velocity of the electrons as they strike the anode in the ordinary construction. As is well-known, this disintegration affects the operating characteristics of the tube and in time renders the tube inoperative for its purposes. My invention increases the power capacity of the tube, avoids disintegration of the anode, reduces the heating of the anode, avoids expensive and, cumbersome cooling means for the anode, avoids the disadvantages of negative grid bias, and in general results in a highly efficient tube.

I wish it to be understood that the forms shown in this application are merely illustrative and not definitive, it being apparent that changes may be made in the proportions, shapes, and designs to suit various desired operating conditions.

I claim:

1. Means for amplifying electrical signals, comprising an input transformer, and an electron discharge device connected to the secondary of the transformer, the said electron discharge device comprising an electron emitting electrode, an electron collecting electrode, and a control grid which is connected to the secondary of the transformer in such a way as to receive a portion of the current transferred by the transformer, means for maintaining the control electrode at a relatively high positive potential with respect to the cathode whereby the flow of electrons from the cathode toward the control electrode is accelerated, the said current serving to create a magnetic field around the control grid to prevent it from being struck by electrons.

2. Means for amplifying electrical signals, comprising an input transformer, an electron discharge device connected to the secondary of the transformer, the said electron discharge device comprising an electron emitting electrode, an electron collecting electrode, a control electrode connected to the secondary of the transformer, and an accelerating electrode for accelerating the flow of electrons from the electron emitting electrode to the electron collecting electrode, and means for passing a current through the accelerating electrode for the purpose of creating a magnetic field around it to prevent it from being struck by electrons.

3. In an electrical network an electron-discharge device containing an electron emitting electrode, an electron collecting electrode, and a control electrode, means for applying a high potential to the control electrode for the purpose of accelerating the flow of electrons toward the electron collecting electrode, and means for passing a current through the control electrode for the purpose of creating a magnetic field around it to prevent it from being struck by electrons.

l. In a circuit including an electronic tube comprising an electron emitting electrode, an electron collecting electrode and an accelerating electrode and wherein the accelerating electrode is maintained at a higher positive potential with respect to the cathode than the anode, the method of protecting the accelerating electrode from bombardment by the electrons, which comprises creating a magnetic field about the accelerating electrode by passing a current through the accelerating electrode to thereby deflect the electrons therefrom.

5. In an electrical network including a thermionic tube comprising at least an anode, a cathode and a control electrode, a transformer, means for connecting the secondary of the transformer t0 the control electrode, means for connecting a source of current to the primary of said transformer, means for maintaining said electrode at a relatively high positive potential with respect to the cathode and means for passing current through said control electrode to thereby produce a magnetic field about said control electrode and prevent electrons emitted from said cathode from striking the control electrode.

6. The system described in the next preceding claim in combination with means for maintaining the anode at a positive potential with respect to the cathode and means for maintaining the control electrode at a higher positive potential than the anode.

7. In an electrical network including a thermionic tube having at least a cathode, an anode and an auxiliary electrode, a heating circuit for said cathode, means for maintaining said auxiliary electrode at a relatively high positive potential with respect to the cathode to greatly increase the fiow of electrons from the cathode toward the auxiliary electrode, said auxiliary electrode being formed in the shape of a coil and means for passing current therethrough so as to produce a magnetic field to deflect the electron stream away from said auxiliary electrode and means for maintaining the anode at a relatively low positive potential with respect to the oathode whereby the cathode acts mainly to absorb the electrons deflected by the auxiliary electrode.

SAMUEL G. FRANTZ.

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