US2121360A - Electronic oscillator - Google Patents

Description

June 21, 1938. L, MALTER 2,121,360

ELECTRONIC OSCILLATOR Filed March 28, 1936 2 Sheets-Sheet l June 21, 1938. L. MALTER ET AL ELECTRONIC OSCILLATOR Filed March 28, 1936 2 Sheets-Sheet 2 nnnnn Patented June 21, 1938 UNITED STATES PATENT OFFICE ELECTRONIC OSCILLATOR Application March 28, 1936, Serial No. 71,360

5 Claims.

Our invention relates to electronic devices. More specifically, our invention deals with electronic tubes which depend upon the emission of secondary electrons.

We are aware of electronic devices in which a magnetic field, whose lines of force'are substantially parallel to the cathode, is employed. Such devices are called magnetrons, and require a heated cathode as an electron emissive source. One of the Objects of the present invention is in means for establishing electronic oscillation without the uses of the heated cathode type of electron emitter.

Another object is to cause electronic oscillations to be established between a pair of concentric cylindrical electrodes one of which has an electron emissive surface. A further object is to create a push-pull type of electronic oscillator. A still further object is to restrict the electronic movements to a region between the electrodes and thereby prevent excessive movement of electrons which will not contribute to efiicient operation.

Our invention may be best understood by rel.- erence to the accompanying drawings in which Figure I is a schematic diagram of one embodiment of our invention,

Figure II is a schematic diagram of an electronic oscillator embodying our invention and including electronic shields,

Figure III is a view illustrating a modification of Figure II,

Figure IV is a diagram of a push-pull oscillator embodying our invention,

Figure V is a view illustrating a modification of Figure IV, and

Figure VI is a diagrammatic view showing further modifications of my invention.

In describing the several figures similar reference numerals will be used to indicate similar elements. In Figure I within an evacuated envelope I, a pair of concentrically arranged cylindrical electrodes 3, 5 are suitably mounted by supporting wires 1, 9. The inner cylinder 5 has its outer surface treated with caesium on silver oxide or any other suitable material to make this electrode surface electron emissive. the outer or accelerating electrode preferably over-lap the inner or electron emissive electrode.

The accelerating electrode is maintained at a positive potential with respect to the emissive electrode by a polarizing battery H. A tunable circuit I3 is serially connected between the electrodes as shown. The tunable circuit is composed of'an inductor l5 and a variable capacitor The ends of (Cl. 2508B) Figure I. battery 2| may be used as a source of energy.

The theory of the operation of our device is not entirely understood but it is believed that a small amount of residual gas within the envelope or a photo-electric eifect of light falling on the electron emissive surface may release electrons from the surface of the electron emissive element. These electrons start toward the positively charged accelerating anode at relatively high velocity. The magnetic field causes these electrons to follow a curved path which extends out wardly from the inner electrode toward the anode and back toward the cathode. The electron movement, or some similar effect, starts transient currents flowing in the resonant circuit l3. These currents establish potentials which attract the electrons toward the secondary emissive surface at relatively high velocities. The electrons moving at high velocities give up their energy upon striking the electron emissive surface and thereby release a larger number of electrons. These electrons in turn start toward the accelerating electrode which has again become relatively positive and the cycle is repeated. At each repetition of the cycle increasing numbers of electrons are emitted. The increasing electron emission and movement supports and sustains oscillations in the tunable circuit I3.

The embodiment of our invention illustrated in Figure II is similar to Figure I with the addition of means to prevent the electrons from taking paths outside of the juxtapositioned electrode surfaces. A pair of discs 23, 25 having a diameter intermediate the diameter of the accelerating and emissive electrodes are positioned adjacent the ends of the emissive electrode by supporting leads 21, 29. The disc shape electrodes are connected to the battery 3|. The positive terminal of this battery 3| is connected to the negative terminal of biasing battery II. The disc shape electrodes may be maintained at the same or different negative potentials. The negatively polarized discs will maintain the electron field within the proper boundaries for maximum efflciency. These discs are preferably made of a material which does not impair the magnetic field.

In Figure III a modification of Figure II has been illustrated in which a pair of mica discs 33, are substituted for the disc electrodes 23, 25.

The mica discs are self-biasing; i. e., electrons strike the disc and charge it negatively. The negatively charged discs repel electrons which might otherwise follow paths beyond the adjacent surface or the accelerating and emissive electrodes.

In Figure IV, a schematic representation illustrates an embodiment of our invention applied to a push-pull oscillator. Within an evacuated envelope H a cylindrical accelerating anode 49 is supported by suitable wires 45. A pair of cylindrical electrodes 41, 49 are concentrically mounted within the accelerating anode by supporting wires SI, 53. The outer surfaces of these electrodes 41, 49 are treated to render them highly secondary emissive. The leads BI, 53 from the electrodes 41, 49 are respectively connected to the opposite terminals of a tunable circuit which is composed of an inductor 51 and a capacitor. A polarizing battery 0| is connected between the accelerating anode 43 and the mid-point 63 on the inductor 51. The positvie terminal of -the battery is connected to the anode. The magnetic field has been represented as a magnetic core 01 which is energized by current from battery 09 flowing in the solenoid winding II. It should be understood that a solenoid type winding may be used in place of the electromagnet shown. Disc shape electrodes 23, 25 may be placed adjacent the ends of. the cylindrical electrode 41. Likewise disc shape electrodes 23, 25 may be located adjacent the ends of the cylindrical electrode 49. The disc shape electrodes 23, 25 are biased negatively by suitable connections to negative termirials of a battery 3|. The positive terminal of the biasingbattery 3| is connected to the positive terminal of the polarizing battery BI.

In Figure V the essential elements are similar to the elements of Figure IV. In the instant arrangement the electrode arrangement is reversed. The inner electrode 8I is made with an electron emissive surface, and the pair of outer electrodes 83, 05 act as accelerating anodes. The accelerating anodes 83, 85 are connected to the terminals of the tuned circuit 55. The inner electrode 8| is connected to the negative terminal of the battery GI whose positive is connected to the mid-point 63 of inductor 51, The magnetic field may be due to an electromagnet, permanent magnet or solenoid.

The theory of operation of each of the pushpull oscillators is essentially the same as the single electronic oscillators described above. Inasmuch as push-pull operation is well known to those skilled in the art, a detailed description is unnecessary. It should be understoodlthat various features of the several embodiments of our invention may be combined. By way of example, he accelerating and emissive electrodes of Figures I, II or III may be interchanged, accompanied, of course, by a proper phasing of the biasing battery. Likewise, the disc or shielding electrodes of Figures II or III may be employed with the arrangement shown in Figure V, as for example illustrated in Figure VI.

Referring to Figure VI, within an envelope I00 are arranged a pair of inner cylindrical electrodes IOI, I03. The outer surfaces of these electrodes are treated to make them secondarily emissive. Adjacent the ends of the inner electrodes are equivalent to the operation of the circuits previously described.

We claim as our invention:

1. An electron oscillator comprising an evacuated envelope, a hollow cylindrical electrode mounted within said envelope, a pair of. cylindrical electrodes of substantially the same diameter spaced apart and coaxially mounted within the first mentioned electrode, said pair of electrodes having surfaces adapted to emit secondary electrons upon impact of primary electrons, a tuned circuit, connections from one of the terminals of said tuned circuit to one of said pair of electrodes and from the other terminal to the other electrode of said pair, a source of polarizing potential connected beween the outer electrode of said concentrically mounted electrodes and said tuned circuit, and a magnetic field whose lines of force are substantially coaxial with respect to said concentrically mounted cylinders.

2. An electron oscillator comprising an evacuated envelope, a cylindrical electrode mounted within said envelope, said electrode having suriace adapted to emit electrons upon electron impact, a pair of hollow accelerating anodes spaced apart and concentrically mounted with respect to said first mentioned electrode, a tunable circuit, connections from said tunable circuit to said pairs of electrodes, a source of biasing potential connected between said first-mentioned electrode and said tuned circuit, and a. magnetic field whose lines of force are substantially coaxially arranged with respect to said concentrically mounted electrodes.

3. A device of the character of claim 1 including means for maintaining the electronic movements within the juxtapositioned electrode surfaces.

4. A device of the character of claim 2 including means for maintaining the electronic movements within the juxta-positioned electrode surfaces.

5. An electron oscillator comprising an evacuated envelope, a cylindrical electrode mounted within said envelope, a pair of electrodes spaced apart and concentrically mounted with respect to said first mentioned electrode, at least one of said pair of electrodes having a surface of secondarily emissive electron material, a tunable circuit, pushpull circuit connections between said tunable circuit and said electrodes, means for polarizing said first mentioned cylindrical electrode positively with respect to said emissive electrode or electrodes, and means for establishing a magnetic field whose lines of force are substantially coaxial with respect to said cylindrical electrode.

LOUIS MALTER. JAN A. RAJCHMAN. ROBERT RHEA GOODRICH, 2ND.

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