US2171980A - Electron discharge device - Google Patents

Description

Sept. 5, 1939.

c. w. HANSELL ELECTRON DISCHARGE oavrcs Filed March 13, 1937 2 Sheets-Sheet l INVENTOR CZ/IREA/CE M4 HANSL-Ll.

ATTORNEY Sept. 5, 1939.

c. w. HANSELL 2,171,980

ELECTRON DISCHARGE DEVICE Filed March 13, 1937 2 Shee ts-Sheet 2 MOM/[470R a 0 6 5i i A Tm-mu l? INVENTOR CZARENtZ-W/Ml/Jfll BY ATTORNEY Patented Sept. 5, 1939 PATENT OFFICE 2.111.980 ELECTRON DISCHARGE DEVICE Clarence W. Hansell, Port Jefferson, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application March 13, 193'1, Serial No. 130,646

10 Claims.

This invention relates to electron discharge device ultra high frequency oscillation generator v circuits, and particularly to spch of these circuits which utilize the finite time of travel of the electrons within the envelope of the device for producing conditions which are suitable for the generation of oscillations.

One of the objects of the present invention is to provide a novel form of electron .discharge device ultra high frequency oscillation generator in which a negative resistance characteristic is set up due to the motion of electrons within the envelope of the electron discharge device.

In the drawings, Fig. 1 illustrates, schematically, the essential features of one form of ultra high frequency oscillator in accordance with the invention; Fig. 2 illustrates the oscillator of the invention in connection with a utilization circuit; Fig. 3 shows how the oscillator of the invention may be modulated and used as aradiating element; and Fig. 4 illustrates a modification of the oscillator .of the invention.

Referring to Fig. l more specifically, there is shown an electron discharge device having within an evacuated envelope E, a cathode C, surrounded by a negatively charged focusing electrode F, and a curved anode member A in the /form of a strip of metal. Anode A is supported by means of metallic wires S from a glass stem or press P at one end of the device, while the cathode C and focusing electrode F are supported from a press at the opposite end of the envelope. A source of direct current energy B supplies the anode A with a positive potential relative to the cathode over a 5 circuit path extending from connection D and supporting wires S to the anode. The cathode C is supplied with heating energy from leads L which connect with a source of electric current B, while the focusing electrode F is maintained 0 at a negative potential relative to the cathode C by means of an adjustable potential source of energy B" which supplies potential to F over a path including lead M, metallic clamps N (surrounding the glass press) and metallic strips R 5 which supPQrt focusing electrode F.

The operation of the oscillation generator is as follows: Electrons leaving the cathode C are focussed upon a relatively small area near the center of the anode A. If, for any reason, one end 50 of anode A is caused to have a potential higher than the other end, the electron stream will be deflected from the center'of the anode toward the end which has the most positive potential. In practice, fluctuations in potential due to ther- 55 mal agitation and like causes, should be sufficient to give rise to momentary potential fluctuations sufficient to start oscillation. Although the stream of electrons is bent toward the end of the anode having the highest positive potential, the electrons do not arrive at, or approach close to, 5 the anode until some time later because a finite interval of time is required for them to travel from the cathode to the anode. This interval of time is made equal to approximately one-half cycle of the natural frequency of the anode when 10 the anode is used as a half wave oscillator. Thus, the electron stream arrives at, or close to the side of the anode which had the highest positive potential a half cycle later in time, by which time of arrival the oscillations in the anode have 15 changed the potential of this side of the anode from maximum positive to minimum positive. In other words, by suitable choice of the d mensions of the elements of the electron discharge device and byeorrect choice of potentials, mata ters are arranged so that the'electrons impinge on one portion of the anode A after the potential on that portion has changed to a low positive value. Thus, due to the-time required for the electrons to travel from cathode to anode being 25 equal to approximately a half cycle in time, the effective current flows to portions of the anode having their least positive potential and tends to make the potentials still less positive. This is a condition for the generation of oscillations in the electron discharge device. The time required for electrons to move from cathode to anode will, in practice, tend to be a little greater than the interval of one-half cycle of electrical oscillation along the half wave anode. This is because the alterhating component of current carried by the electrons is set up by the electric field of the electrons. An electron is normally inducing a flow of current to an electrode during the whole time interval in which it approachesthe electrode and the current ceases when the electron strikes the electrode. Therefore, the electron current may be said to precede in time the actual electron posi-,- tion with respect to time.

Fig. 2 is a schematic circuit illustrating the oscillator of the invention coupled to suitable utilization means. In this figure there are shown a pair of capacity platesQ which are located externally of the envelope E and. coupled to opposite sides of the anode A. Plates Q are coupled 59 through a transformer T to a suitable modulator which, in turn, is coupled to an antenna.

Fig. 3 shows, by way of example only, how the oscillations generated by the electron discharge device oscillator may be modulated by a suitable circuit, herein shown as a microphone V and an amplifier for amplifying the speech. waves impinging upon the microphone. Variations in the speech input circuit obviously vary the potentials applied to the anode A by means of potentials superimposed through transformer T onthe anode lead D. v.Ihe oscillator is here shown located in the focus of a suitable reflector for radiating its energy directly without the intermediary of an antenna. V

Fig. 4 illustrates a modification of the electron discharge device of Fig. 1 and shows suflicient elements necessary to an understanding of themodification. In this figure the capacityplates Q, which are illustrated in Fig. 2 as being external of the envelope, are located within the envelope E for capacity coupling with the opposite sides of the anode. If desired, inductive coupling to the anode, rather than capacity coupling, may be used to transfer high frequency energy to an output circuit.

In some cases the operation of the oscillator of my invention may be improved by application of a magnetic field in the direction of the axis of the tube in order to improve the focusing of the electron stream upon the anode. Also, I may apply one or more additional electron accelerating and focusing electrodes to the oscillator shown in the figures.

It is to be distinctly understood that the invention is not limited to the precise embodiment shown in the drawings, since various modifications may be made without departing from the spirit and scope of the appending claims. For example, the shape of the anode may be varied considerably to obtain optimum operation, and. the oscillator circuit may be used with means for modulating the amplitude or frequency of the oscillations, or both, by means of varying the potentials applied to the elements of the electron discharge device. Similarly, tlie microphone circuit of Fig. 3 can be replaced by a suitable telegraph keying arrangement without the exerciseof invention, and, if desired, water cooling means can be applied to the anode which can be hollow.

The term strip used in the specification and appended claims is deemed to include metallic bars and rods, and is not to be construed in a limited sense.

What is claimed is:

1. An electron discharge device having an evacuated envelope and an anode in the form'of a curved metallic strip within said envelope, metallic means supporting said anode substantially at the center of said anode, a cathode having an effective portion located substantially equidistant from the ends of said curved anode and facing the interior thereof, and a focusing elec trode adjacent said cathod'e.

2. An electron discharge device having an evacuated envelope and within said evelope an anode, a cathode, and a focusing electrode in the form of a cylinder surrounding the length of said cathode, said anode being in the form of a curved metallic strip, said cathode being in a plane passing through the axis of said cylinder and the center of said anode, said cathode being located near and equi-distant from the e'ndsof said anode and having an effective portion facing the interior of said anode.

3. An electron discharge device having an evacuated envelope and an anode inthe form of a curved metallic strip within said. envelope,

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means supporting said anode substantially at the center of said anode, a cathode having an effective portion located substantially equi-distant from the ends of said curved anode and. facing the interior thereof, and a focusing electrode surrounding said cathode except for said effective portion.

4. An electron discharge device having an evacuated envelope and an anode in the form of a curved metallic strip within said envelope, means supporting 'said anode substantially at the center of said anode, a cathode having an effective portion located substantially equi-distant from the ends of said curved anode and fac- J ing the interior thereof, a focusing electrode adjacent said cathode, and a pair of plates within said envelope which by virtue of their spacing are capacitively coupled to opposite sides of said anode for deriving oscillating energy from said device.

5. An electron discharge device having an evacuated envelope and an anode in the form of a curved metallic strip within said envelope, means supporting said anode substantially at the center of said anode, a cathode having an effective portion located substantially equi-distant from the ends of said curved anode and facing the interior thereof, a focusing electrode adjacent said cathode, and a pair of plates located externally of said envelope which by virtue of their spacing.

are capacitively coupled to opposite sides of said anode for deriving energy from said device.

6. An electron discharge device in accordance with claim 1, including means supporting said anode and cathode from opposite ends of said envelope.

'7. An electron discharge device having a cathode, a curved anode in the form of a strip of electrically conducting material having its ends located relatively close to and on opposite sides of said cathode, said anode having an electrical length substantially equal to half the length of the operating wave, and a focusing electrode for directing the electrons emitted by said cathode toward said anode.

8. An electron discharge device having a cathode, a curved anode in the form of a strip of electrically conducting material having itsends located relatively close to and on opposite sides of said cathode, said anode having an electrical length substantially equal to half the length of the operating wave, and a focusing electrode for directing the electrons emitted by said cathode toward said anode, the electron transit time between said cathode and anode being greater than the interval of one-half cycle of electrical oscillation along the length of said anode.

9. An electron discharge device oscillator having a curved anode in the form of an electrically open loop whose ends are bent relatively close to each other, a cathode in a space between said ends, with said anode ends on opposite sides of CLARENCE W. HANSELL.

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