US2117089A - Electronic oscillator and multiplier - Google Patents

Description

y 10, 1938- R. R. GOODRICH, 2D

ELECTRONIC OSCILLATOR AND MULTIPLIER Filed March 28, 1936 lumen/$7 12 26.40 QwiaE/ Mar/Z 9 Patented May 10, 1938 Q UNITED STATES PATENT orrle ELECTRONIC ost l lll lggzm AND MULTI- Robert Rhea Goodrich, 2nd, Camden, N. J., as-

signor to Radio Corporation oi America, a corporation of Delaware Application March 28, 1936, Serial No. 71,513

12 Claims. (Cl. 250-36) My invention relates to electronic oscillators tronic device of Fig. I employing a filament type and multipliers. More specifically, my invention cathode, is an electronic discharge device which depends Fig. III is a diagram showing my invention for its oscillation on two sources oi electrons: applied to a push pull oscillator, and

5 one, athermionic source of primary electrons; the Fig. IV is an enlarged sectional view of a uni- 5 other, surfaces emitting secondary electrons upon 1noteniisslial cathode which may be embodied in my electronic bombardment. nven Electronic oscillators and multipliers which de- In Fig. I within a highlyevacuated envelope l pend solely on secondary emission ofler advanare included a pair of electrodes 8, 5, and an aco {ages such high amplification, and quiet opcelerating anode I. Each of these electrodes is eration. However, the operation of such devices tably supported by wir 3, Whi h may is not without disadvantages. The electronic also act as the lead-in conductors. The surfaces stream must be initially started. There are two of th pai of di sh pe e t d s 3. are p accepted theories accounting for the initial triga ly tr at d with erylli m oxi or the lik gering of the electronic stream. In one theory it to make h m i hly electron emissive. The acis is assumed that a photo-emission of electrons aclerating anode may be formed of a circular counts for the triggering effect. In the other band metal Wh ch is preferably d i dits theory, it is assumed that a small amount of reh wn. y a trip l sidual gas is ionized thereby starting the elec- An electronic 8 01' unipotential cathode il tro i m t, is inserted through a suitable orifice is in one of If the photo-emissive type of electrode surfaces the e e odes 5- The end surface of the uniare employed, these surfa es may be highly secpotential cathode 5 is preferably flush with the ondarfly emjssive and 111 operate under high inner surface 2| of the electrode. The cathode vacuum 10- of mercury) t gas is apt I1 is heated by a heater wire 23 in the conven- P to be driven out of the electrodes. This gas will tional mann n o th h at r leads may be 0 ruinthe photo-emissive properties of the elecconnected Within t V OPfi to the supportin trodes. Thereafter, the triggering eflects must conductor la. The other heater lead is connected come from the ionization of the gas. But the to the cathode h a r a ter 25 whi h s joined. ionization of the gas is a critical matter depending t0 the conductor The p t al cathode u upon pressure, t has been found t t critical i1 is likewise connected to the conductor It or as pressures are dimcult to maintain. This is electrode 5.

du t clean-up of th gas by t electrodes A tunable circuit 21 comprising an inductor 29 the l and capacitor 3| is connected between the pairs One of the objects of my invention is to 'comelectrodes 3, The pos v terminal 01 a 5 Mile the secondary electron 'emissive electrode and biasing battery 33 is Connected y means Of 0011- a thermionic electron emitter in an electronic ductol' H to h accelerating de The negad vi th obje t is t supply triggering tive terminal of this battery 33 is connected to a device for a secondary electron emitter. A still tap 35 intermediate the f d 01 he inductor 29. further object isthe embodiment of an electronic A magnetic field. upp ed by a permanent or I emitter whose. surface is treated to be highly electremegnet is arranged so t at its lines of $0 emisswe of electrons upon bombardment by pm ,force are substantially coaxial with the axis of mary electrons and the inclusion of a thermionic the accelerating anodeemitter in the plane of said surface whereby the el 3332:2 5 353g; 3 g i gf g E electronic device may operate substantially inde' accelerated by the anod sand s om e 01111:: g of critical gas pressure or photo-ems electrons strike the electrode 3 at high velocity. W e ectmde Summes An a'dditkfnal object is The striking electrons thus lose their energy and to combine a secondary electron emlsslve element liberate secondary electrons. At the same time and an electronic gun electrode within a high a transient current m tuned circuit sets up evacuated envelope substantially free from ionizan alternating current ms current alternately able makes one of the pair of electrodes 3, 5 positive Figure I is a schematic illustration showing an and negative with respect to the other electrode. embodiment of my invention in an electronic The secondary electrons from the electrode 3 are oscillator, attracted to the momentarily positive electrode 5,

Fig. II represents a modification of the elecand upon impinging on this electrode 5 more sec- M ondary electrons are emitted. These electrons, in tiu'n, are impinged on the then momentarily positive electrode 3. These cycles continue with ever increasing numbers of electrons until the space charge and collection of electrons by the accelerating anode limit the numbers of electrons travelling back and forth between the electrodes 3, 5.

From the foregoing description, it would seem that the cathode could be de-energized once the electronic cycles were started. This is true in many electronic tubes, but I prefer to maintain the cathode heated. The heated cathode, although it may only supply a few of the total number of electrons, acts as a stabilizing element, permits more uniform manufacture of tubes', and more stable operation.

In Fig. II a modification of my invention, employing a filament type cathode, is illustrated. The evacuated envelope M is arranged with a cylindrical anode 43 supported by a conductor 45. A cylindrical electrode 41 surrounds the anode 43 and is concentrically mounted with respect thereto by conductors '46. The-inner surface 49 of the electrode 41 is treated to render it highly electron emissive. A V shape opening is pierced in the electrode 41. A pair of conductive leads 53 are mounted so that their ends terminate within the V without contacting the electrode 41. A suitable electron emitter filament is conductively arranged between the leads 53 and is supported at its center by a wire 55 which is attached to the electrode 41.

The filament is arranged to lie substantially in the plane of the surface of the electrode 41. The filament is heated by a battery 51. A solenoid 59 is arranged to surround the envelope I. The solenoid is energized by a battery 6| The conductor 45 which supports the anode is connected to the positive terminal of battery 53. The negative terminal of the battery is joined to one terminal of a tuned circuit 05 which is composed of an inductor B1 and a variable capacitor 69. The other terminal of the tuned circuit is connected to the conductors 46 which in turn connect to the electrode 41.

The operation of this embodiment of my invention is somewhat diiferent from the circuit of Fig. I. In the present case the filament emits primary electrons. These primary electrons, under the influence of the magnetic field travel outwardly but follow a curved path approaching the anode and returning at high velocity to the surface of the emissive electrode 41. The primary electrons impinging on the emissive electrode cause the emission of increasing numbers of secondary electrons. A transient current in the tuned circuit 65 establishes oscillatory currents which are sustained by and at the'same time aid the electronic movements as previously described. Although the filament may be de-energized I prefer to maintain it in the heated condition in which state it aids the operation of the oscillator.

In Fig. III a schematic diagram illustrates an embodiment of my invention applied to a pushpull magnetron oscillator. A pair of accelerating anodes 1i, 13 are suitably supported within an evacuated envelope 15. Within these anodes 1|, 13 are concentrically mounted a pair of electrodes 11, 19 which are supported by conducting wires 8|. The outer surfaces of the electrodes 11, 18 are treated to render them high electron emissive. A pair of unipotential cathodes 83, 85 are inserted through orifices 81, 89 with the elec- 'of force are substantially coaxial with respect to the longitudinal axis of the several electrodes. The solenoid is energized by a battery 91. This same battery may be used to energize the heaters 9|, 93. The accelerating anodes 1|, 13 are respectively connected to the terminals of a tunable circuit 99 which is comprised of an inductor IM and a capacitor I03. A battery I05 is connected between the junction of the secondary emissive electrodes "-19 and a tap I01 intermediate the ends of the inductor IN. The battery is poled to make the anodes positive with respect to the secondary emissive electrodes.

The operation of the circuit of Fig. III is substantially'the same as the circuit of Fig. II. The push-pull oscillator is so well known to those skilled in the art that further description is not required. It should be understood that the unipotential or electron gun type of cathode is interchangeable with the filament type cathode and vice versa.

Thus, an electronic device has been described which does not depend solely on secondary electron emission, or thermionic emission but combines the useful characteristics of both. The combined application of secondary electron emission and thermionic emission makes the elec-' tronic oscillator and multiplier more stable, reliable, and cheaper to manufacture than those devices which rely solely on secondary emission.

I claim as my invention:

1. An electronic device of the character described comprising an evacuated envelope, an accelerating anode and a secondary emissive electrode mounted within said envelope and including an opening in its emissive surface, a primary electron emitting electrode located within and having an emissive surface flush with said opening, and means for energizing said-additional electrode for the emission of primary electrons.

2. An electronic device of the character described comprising an evacuated envelope, an accelerating anode and a secondary emissive electrode mounted within said envelope and having an opening in its emissive surface, an additional electrode arranged within said opening and having a surface which is substantially in alignment with the emissive surface of said secondary emissive electrode and means for energizing said additional electrode for the emission of primary electrons.

'3. An electronic device of the character described comprising an evacuated envelope, an accelerating anode and a secondary emissive electrode mounted within said envelope, said secondary emissive electrode having an opening in its emissive surface, and a unipotential cathode connected to said secondary emissive electrode and mounted within said opening having its emissive surface substantially flush with said emissive surface.

4. An electronic device of the character described comprising an evacuated envelope containing an accelerating anode, a pair of electrodes disposed on opposite sides of said anode and having surfaces of secondary emissive material, one of said pair of electrodes having an opening within its emissive surface, and an additional electrode, arranged within said opening flush with one of said surfaces and made of a primary electron emitting material.

5. In a device of the character described by claim 1, a tunable circuit connected between said anode and secondary emissive electrode, a source of electrical energy for biasing said anode positive with respect to said secondary emissive electrode, and a magnetic field for influencing electron movement within said envelope.

6. In a device of the character described by claim 4, means for energizing said additional electrode, a tunable circuit connected between said anode and secondary emissive electrodes, a source of electrical energy for biasing said anode positive with respect to said secondary emissive electrodes, and a magnetic field for influencing electron movement within said envelope.

7. An electronic device of the character described comprising an evacuated envelope, an accelerating anode and a secondary emissive electrode mounted within said envelope, an additional electrode one of the surfaces of which is substantially in the plane of the emissive surface of said secondary emissive electrode and which may be energized to emit primary electrons, means for energizing said additional electrode, a tunable circuit connected between said anode and secondary emissive electrode, a source of electrical energy for biasing said anode positive with respect to said secondary emissive electrode, and a magnetic field for influencing electron movement within said envelope.

8. An electronic multiplier comprising an evacuated envelope, an accelerating anode of cylindrical form; a hollow cylindrical electrode surrounding said anode and having an inner surface of secondary electron emissive material; and

9. An electronic multiplier comprising an evacof accelerating anodes of hollow cylindrical form; a pair of cylindrical electrodes mounted within said anodes and having outer surfaces of secondary emissivematerial; and a pair of thermionic cathodes connected to said pair of cylindrical electrodes and having electron emitting surfaces disposed substantially in alignment with said outer surfaces.

. 10. A device of the character of claim 8 in cluding a magnetic field for influencing electron movement within said envelope, a source of power for energizing said cathode, a tunable circuit, a source of biasing voltage and serial connections between said anode, electrode, source of biasing voltage, and tunable circuit.

11. A device of the character of claim 9 including a magnetic field for influencing electron movement within said envelope, a source of power for energizing said cathodes, a tunable circuit, connections from said tunable circuit to said accelerating anodes, and a source of biasing voltage connected between a point intermediate the terminals of said tunable circuit and said electrodes.

12. An electronic device of the character described comprising an evacuated envelope, an accelerating anode and a secondary emissive electrode mounted within said envelope and having an opening in its emissive surface, an additional electrode mounted within said opening and having a surface which is substantially in alignment with the emissive surface of said secondary emissive electrode and which may be energized to emit primary electrons, means for energizing said additional electrode, a tunable circuit connected between said anode and secondary emissive electrode, a source of electrical energy for biasing said anode positive with respect to said secondary emissive electrode, and a magnetic field for influencing electron movement within said envelope.

ROBERT RHEA GOODRICH, 2ND.

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