US2087747A - Thermionic discharge device - Google Patents

Description

July 20, ll9`37.- "A. YOUNG Y 2,087,747 n 'runulourvmscngne DEVICE y ,Fneanom `116, 1932 NIJ,

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. UNITED sTATas i PTENT oFF-ICE y Lv I, Mawr f, .n THERMONIC DISCHARGE DEVKIGEA f Andrew'l. Young, Schenectady, N. AY'.`,r assi|fnor to General Electric Company,- a corporation Aof New York Application November 1c, 1932, semi No'. 642,882 -5 claims. (crus-124) v The present invention, while illustrated with surrounding heat. shield 5. Within the shell! is particular reference to an electric lamp, is of gena resistance heater .8 consisting of tungsten, eral application to electric discharge devices conmolybdenum, or other suitable refractory metal. taining one or more themionic electrodes. The This resistance is connected. (as shown) at ,its 5 invention will be described with particular reflower end to the shell'l andto its upper end to a f5 erence to an electric lamp containing sodium conductor 1, suitable insulation being provided vapor. An electric device of this character, a between the conductor 1 and the shell as indicated thermionic electrode, should be allowed to assume at 0. A circuit conductor! is.-;loined,to the shell its normal operating temperature before the disstructure, both conductors 1 and 9.'being sealed charge is permitted to occur between the elecvinto the envelope I lin the usualxm'anner. j vThe '1o trodes. Otherwise serious disintegration of such same arrangement is provided for the electrode electrode willoccur. 3. In this case a conductor I0 vis provided leading It is the object of my invention to provide a to` one end of the resistor II sealed through the simple structure with a simple sytemof connecn envelope .I, thisV resistor being surrounded by a operation by a single application of voltage withterial, such` as. alumina or beryllia, throughout out complicated auxiliary devices. My invention substantially its; entirelength within thev lamp provides a structure and electric connections to'v prevent lthe discharge from the oppositeelecrendering a vaporlamp of this character suitable trode passing directly tothe leading-in wire from for highway lighting or other installation where the' electrode 2` instead of traversing thewdis- 2o Y a minimum' of complication and oversight fare charge space. The shell I3 of: electrode 3 is con-A highly desirablej nected to'a conductor I4 which is also surrounded As will be pointed out in greater particularity by aninsulating sleeve ISV-of alumina or beryllia in the appended claims my invention comprisesa and is lsealed into the envelope of the llamp as. lamp or other thermio-nic discharge device conindicated. c v Y .g 2g taining electrodes which are initially' brought The envelope contains preferably acharge of Y into operating temperaturebythe passageof curattenuated -`gas as for example a gas ofv the rent whilethe discharge space between theelec-f noble gas" group, v'such as'argon yor neon. The' trodesris short-circuited by a conductor containpressure of. this gas preferably should be ,within ing a thermostat. This thermostat vis indirect the limits of about 0.2 to 4 millimeters of mercury. '30 heat-receiving relation to some part of the lamp, Within the envelope I there is also a quantity of 8S fOr exemple, the bulb Wall adjacent Oneof the vaporizable material, such as sodium or-A other electrodes, S0 that when the electrode temperaalkali metal,`-or other metal such as thallium or ture rises to a value at which the `usual emission cadmium as indicatedat I8. The lamp is'shown 351s obtained the circuit between the electrodes is" as being ycontained within an outer chamber I1 35 Opened, thereby Sensing the discharge t0 Operate consisting of glass, or other transparent material, through the gasin order to conserve heat generated within the The accompanying drawing is a side elevation lamp whereby the pressure ofthe vapor within Partly in Section 0f u lamp embodying my inventhe lamp is maintained at an operating condition.

0 tion and also indicates circuit connections for For the better conservation of heat aidouble- `40` Sueh 9.1811111. walled evacuated chamber .of the Dewar flask Referring to the drawing the lamp illustrated type may be employed as the outer heat concomprises a somewhat elongated envelope I conservat'or. The conductors 1, 9, I0 and Il are Sistina 0f 81u58 0r Silica eentining electrodes 2, 3 suitably sealed within the cover I8 of the heat 4 which preferably are similar in construction to conserving jacket I1. 45

permit'the lamp to be operated on alternating The conductors 1 and Ilare connectedto av Current However, my invention is equally apsource of electric mains I9 and. ZIIFfrom Iwhich. plicable to direct current' devices. In an alterelectric energy for operating therlamp is supnating'current device, the electrodes each coxn-y plied. One of these conductors preferably is, ,l prise a shell l of nickel, iron, molybdenum, or a provided witha suitable switch 2| for completing. 50 suitable alloy, as is well known. "I'his shell is the lamp circuit. It is obvious that this switch coated with thermionically active material as for may have any desired character and may be either example an oxide of an alkaline earth, preferably hand operated or electrically operated as is well barium oxide, as is also well known. The shell known. 4ilidiacent the upper end of the bulb and Y preferably but not necessarily is provided with a within close heat receiving relation tothe bulb is 55' 20 pressing the voltage of the mains I9v and 20 upon a thermostat 22 which may be ot well known construction and therefore will not be described in detail. 'I'he conductors 1 and Il are connected in circuit with this thermostat by electric wires 23, 24. It will be observed that the circuit 23, 24 including the thermostat 22 is in shunt to the electric discharge space between the electrodes 2and3. Y l.. .Y

When the lamp is put into operation by Aclosing the switch 2| the heaters 6 and Il are connected in series across the supply mains I9 and 20 and become heated at operating temperature. Ihe heat evolved from these heaters raises the electrode shell surrounding the heaters to an` electron-emitting temperature and the heat from the electrodes also causes the sodium or other vaporizable material I6 to be at least partially vaporized. At a predetermined temperature of the electrodes, which ordinarily is about 900 C., the

thermostat 22 opens its contacts thereby imthe electrodes 2 and 3. At an electrode temperature of about 900 C. sufficient electrons are emitted to support an arc-like discharge of high luminosity through the vapor or mixture of gas and vapor in the discharge space. The discharge starts immediately at substantially normai current value. For example, the described device may be operated with a space current of about six to seven amperesjthe drop of voltage between the electrodes being about 15 volts. 'I'he electrode heaters 6, yll function during operation alsoas' steadying impedances for the arc operating between theD electrodes 12, 3. If the operating voltage had been impressed upon the electrodes before the r4electrodes had assumed their operating temperature, then in that case deleterious disintegration of the electrodes would have occurred. This would have shortened the useful A life of the lamp. l

What I claim as new and desire to secure by LettersPatent of the United States, is,-

l. An electric discharge device comprising an envelope, an ionizable material therein, a plurality of spaced thermionic electrodes in said envelope,

said electrodes'each comprising' a shell andresistance heater for said shell, leading-inV conductors sealed into said envelope and being connected to said electrodes, a short circuiting conductor connected-to each of said electrodes and having a portion vof 'fits length external to said envelope, and a thermostat located in heat-receiving relation to one of said thermionic electrodes, and being arranged to open the short circuit-ing conductor circuitj when said thermionic predetermined tempermeansiorheating said shell, one end oi."V said re- Vspective heating means being electrically connected to the associated shell, conductors sealed Ainto said envelope and being respectively electrically connected to the other end of said heaters a thermostat located external to said envelope and in heat-receiving relation to one of said electrodes.

and an electrical circuit including the contact members of said thermostat connecting said electrode shells.

3. An electric lamp comprising an elongated envelope, two thermionicV electrodes spaced at opposite ends of said envelope, each of said electrodes comprising a shell and a resistance heater therefor, conductors sealed into said envelope adjacent one oi' said electrodes and connected to opposite ends of the heater for said electrode, a second set of conductors also sealed into. said envelope adiacent said electrode and connected to opposite ends ofthe heater of the second electrode, a refractory coating for said'second setoi' conductors, a circuit connected between said electrodes and thermostatic means for opening said circuit when said electrodes have been heated to an operating temperature.

4. An electrical discharge device comprising a sealed envelope containing an ionizable medium, a plurality lof cathodes, an electrical circuit including said cathodes, `an anode electrically cony which is unconnected with the associated shells,

nected ytoeach cathode, means sensitive to temperature variations 'disposed in effective relation to a cathode to open said circuit'when said cathode reaches anelectron emitting temperature and means for impressing a potential between said and thermostatic' means in theconductor adapted to be aiected by heat from an electrode to open the shunt connection at a predetermined heat of the electrode.

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