Gaseous discharge device

Abstract

Claims

April 1953 F. W. STUTSMAN 2,636,144 GASEOUS DISCHARGE. DEVICE Filed Feb. 3, 1951 Patented Apr. 21, 1953 GASEOUS DISCHARGE DEVICE Paul W. Stutsman, Needham, Mass., assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application February 3, 1951, Serial No. 209,220 Claims. This invention relates to gaseous-electron-discharge devices containing electrodes comprising wires of extremely small diameter. This invention discloses the discovery that, when an electrode comprising an extremely fine wire having a diameter on the order of .001 of an inch is positioned adjacent a source of electrons, such as an indirectly-heated cathode in a gaseous medium, and a positive voltage is applied to said electrode with respect to said electron source, electrons attracted from the source toward the electrodes will collide with gas molecules producing ions and electrons greatly in excess of that required to maintain a discharge between the electron source and the fine wire electrode. As a result, if an anode having a substantial surface is placed in the vicinity of the discharge between the electron source and the fine wire electrode, for example, by making the anode in the form of a cylinder surrounding both the electron source and the fine wire electrode, a substantia1 quantity of electrons will flow from the electron source to theanode even with no potential difierence between the anode and the electron source. Indeed, it has been found that substantial quantities of electrons will flow from the electron source to the anode when the anode is negative with respect to the electron source, the magnitude of this electron flow being a function of the positive voltage applied to th thin wire electrode and the amount of the negative voltage applied to the anode. Because of this phenomenon, it is possible to use a gaseous-electron-discharge device of this type as a voltage-transforming device, wherein relatively high voltage at low current may be converted to low voltage at relatively high current. It has further been discovered that, if a particular potential is applied between the thin wire electrode and the electron source, and a positive potential is applied to the anode, the drop between the anode and the electron source will remain substantially constant over a relatively wide range of anode currents, thus demonstrating that the device has the characteristics which will enable it to operate as a gaseous-voltage-regulating tube, and having the advantage that the desired regulating voltage may be adjusted by adjusting the potential applied to the thin wire electrode, and also that the regulated voltage developed between the cathode and anode of the device will be considerably below the operating voltages obtainable by other types of gaseous- 2 tube regulators. For example, the regulated voltage may be on the order of ten volts or less. Further, since the voltage developed between the cathode and anode may be varied as a function of the thin wire electrode voltage, the device exhibits the properties of an amplifier, and may be so used, if desired. It has been discovered that a particularly useful gaseous medium for this discharge device comprises a mixture containing substantially ninety per cent krypton and ten per cent xenon at a total pressure of one hundred microns of mercury. Other and further objects and advantages of this invention will be apparent as the description thereof progresses, reference being had to the accompanying drawing, wherein: Fig. 1 illustrates a longitudinal, cross-sectional view of a gaseous-electron-discharge device embodying this invention, taken along line l-l of Fig. 2; Fig. 2 illustrates a transverse, cross-sectional view of the device shown in Fig. 1, taken along line 2-2 of Fig. 1; and Fig. 3 illustrates a graph showing operational characteristics of the device illustrated in Figs. 1 and 2. Referring now to Figs. 1 and 2, there is shown an envelope H) which may be, for example, of glass, said envelope being sealed to a glass press II at the bottom thereof. Extending upwardly from the glass press I l is a plurality of supports which are attached to various elements of the discharge device. A support I2 is attached to a cathode I3 which is shown here as a cylinder coated with electron-emissive material I4, and heated by a heater wire I 6 connected to the support and lead-ins l1 and I8, respectively, said lead-in members extending through the glass press II to provide electrical contacts external to the envelope [0. Surrounding cathode l3 and spaced therefrom is an anode cylinder l9 which is coaxial with the cathode l3. Cylinder 19 is supported by a pair of side rods 20 and 2|, respectively, whose lower ends are imbedded in the glass press ll. Upper and lower mica spacers 22 and 23, respectively, cover the ends of anode cylinder l9 and extend slightly over the ends of the cathode cylinder [3, said mica spacers extending substantially out to the walls of envelope l0. Rods 20 and 2| extend through mica spacers 22 and 23, thereby insur- I 3 24 extends between the mica spacers 22 and 23 parallel to the cathode cylinder 13 at a point approximately a half wave between the cathode cylinder [3 and the anode cylinder l9. At its lower end Wire electrode 24 is attached to a leadin support 25, and at its upper end wire electrode 24 is attached to a spring support 26 which, in turn, is .attachedc. asby Welding, toarod 2'1,v one. end of which is imbedded in glass presswl I and extends upward through the mica spacers 22 and 23 outside the anode cylinder I9. Referring now to Fig. 3, there is shown a graph illustrating the operation of the-gaseous-d is charge device of Figs. 1 and Alongthe-axis. of ordinates is plotted anode. voltagerelative to..- the cathode I3, while along the axis'of aabscissas is plotted anode current in milliamperes. Curve 28 illustrates the characteristic"of'the" device Which would allow its use as a step-downvoltage transformer. As isishown by point 29, at zero. current, .theanode voltage is minus between one and ftwo'.voltspvvhen one hundred and. ten voltsare applied. between the auxiliary wire electrode. and. the. cathode, ,saidj auxiliary wire. elec. trode." voltage. being... labeled egv on the. graph,.,of. Fig; 3. With .eg. remainingconstant at one. hundred and ten volts, thebanode voltage. becomes less-negative the anodecurrent increases. from zero luntil at.,a pproximately thirty milliamperes 0t; current-,. the. anode. voltage. is approximately 0 zero, asiis. indicated...by ,point. 3%... Thus, if one hundred.and tensvoltswareapplied .to the. auxiliary electrode, and a current of arounclfifteen milliamperes.isaallowed. .to .ilow. inthe. anodecathode. circuit, a..negative,voltageon the. order of. one; voltrwill. appear. between-the anode and the cathode, saidcsvoltage.bein available, for example, for... biasing-l other. electron-discharge tubesor. .ioresuppl-ying, a..heatei:. current to. other electron-discharge tubes; As is shown in this graph by Way of example; with the auxiliary electrode held constant, for example; at.- one hundredand ten-.:volts-,; the. plate voltage rises rapidly between currents. oiiorty fifth mil-liamperes'. QfwPlEttfi current +untilg-the anode. voltageqreacheea :voltage. on. the; order. .of eight or ten volts, at which time the voltage; again levelsrofi asthe.dischargevdevice approaches .conditionsxo iarcidischarg-ev If a vo1tage,-.-.oi,-.for example .;.volts ;is to thee electrode; anode-cathode voltage dropswill remain- .suhstantially .cons,tantat approximately one-half. volt fonarcurrent range-offrom twenty to =f1orty:-milliamperes,; thus providing a characteristic which may be used to produce ;;a clowvoltageLregulatedoutnut acrossztheanode-cathode circuit of the. devic:e;.;said; anode: being. connected; for example, to; a higherwoltage; source through a dropping resistom:inxaccordance: 'witlr..:we1bi knownvoltagez regulator: practice." This is illus; trated by a curve 3! in Fig. 3. If. the voltagev applied to theauxiliary electrode is zero,- the. anodewathodei voltage .dropmvili'b'e on the orderof'eiglit volts, Wl1i1e;ior variousivoltrzages applied to. theauxiliary 61Gctr02d63b6tlll68ll zero and. fifty-*volt various curveschaving subs stantially c onstantyoltages in. the: currentirange betwceir twenty and:'fortwmilliamperes: may be obtainedr- These; curves are. shown, for example; by the dotted li nes 3:2? aid 'curves substantialiy matching. with: curve. 282% kWh-err: anode :currents exceed between. forty'land iiity miiliamperes.c. It; ShQl'lld,19BfHOtSBditihfll'ttthE efficiency; of genere? ation'ofrthe exccsspositiveyions by:.;therthirr ,wire electrode is idependentomthe;diameter of the thin diameters as high as .004 of an inch. wire. For optimum results, the diameter of the thin wire should be much less than the length of the mean free electron path, for example, one tenth the length thereof. In addition, the gas pressure must be sufficient to produce enough ions to substantially neutralize the electron space charge of the device. While the particular gaseous' medium :disciosed herein comprised krypton and xenon' at a pressure oi: one hundred. microns of mercury, other gases, such as mercury or helium, could be used, and the pressure of the gaseous medium could be as low as fifty microns of'mercury. At the low pressure of fifty microns, results may be obtained with thin wire electrode When higher-pressures are used, for example, pressures of greater than one thousand microns of mercury, the'thilrwire electrode diameter should be very small-,iiorexample, less than .001 of an inch. This completes the description of the particular embodiment of. the invention illustrated herein. However,v many modifications thereof. will be apparent to persons skilled inthe. art without departingirom the-spirit and scope of. this invention For example, the auxiliary wire. electrode hasacurrent voltage charaoteristicwhich prevents an are from occurringbetween the electron source: and. thcauxili-ary electrode. This portion 011 the tube could lee-used alone as a resistance having. a positive voltage currentcharacteristic throughout its entire range of, appliedvoltages. In. addition, the particular configuration of the electrodes and their support. means'is-by way of illustration only. Accordingly. it 'is desired that this. invention be not limited by-the. particular details of the embodiment described herein, except as defined by the-appended claims What is claimed-is A, gaseous-eiectron.-discharge device com.- prising an envelope containing a gaseous medium, asource of electrons, an anode,.and an auxiliary electrode, saidelectrode comprisinga Wire having a diameteron the. order of .001. of an-inch. 2rd gaseouseeleotron-dmcharge device compri-singanenvelope containing a gaseous medium, a source of free electrons, and an electrodesp-aced from said: sour c; said electrode comprisinga wire having a diameter on the order of 1001.01" an inch. 3.= A. gaseous-electron-discharge device comprising-an envelopecontainingaaseous medium, acathode of.theaheated type, ands-an electrode spacedirom. said; cathode, said electrode comprisingea wire. having. a diameter on the-order 013.661 Oran-inch. 4. a A: .gaseous-electronrdischarge device comprisingzan envelopecontaining a gaseous medium, a cathode; an anode, and an auxiliary electrode, said electrode comprising. a=-wire having a diameter on the order or" .001 of an inch. 5: A gaseouselectron-discharge:z device 1,. comprising: an envelopecontaining a gaseousmedium, am indirectly heated cathode;- an. anode, audan auxiliary electrodasa-id electrode comprising a Wirewhaving. a diameter on the order of: aOO-L 0t anyinoh'. 6. A: gaseous-electrondischarge1 device com.- prising anxenvelopecontaining'a gase'ousmedium; a-cathodeyan anode coaxial withsaid cathode, and an: auxiliary electrode; said. electrode comprisinga. wire" having a diameter on: theorder of .001 ofcan inch..- 7-. .A gaseous-electron-discharge device. comprising an envelope containing a gaseousmedium, asourceofelectrons, saidmedium comprising an inert-gas,: and. an electrode spaced: from said source, said electrode comprising a wire having a diameter on the order of .001 of an inch. 8. A gaseous-electron-discharge device comprising an envelope containing a gaseous medium, a source of electrons, said medium comprising an inert gas at a pressure on the order of one hundred microns of mercury, and an electrode spaced from said source, said electrode comprising a wire having a diameter on the order of .001 of an inch. 9. A gaseous-electron-discharge device comprising an envelope containing a gaseous medium, a source of electrons, said medium comprising krypton and xenon at a pressure on the order of one hundred microns of mercury, and an electrode spaced from said source, said electrode comprising a wire having a diameter on the order of .001 of an inch. 10. A gaseous-electron-discharge device, an envelope containing a gaseous medium at a pressure on the order of one hundred microns of mercury, a source of electrons, and an electrode spaced from said source, said electrode having a diameter substantially less than the mean free electron path in said medium. PAUL W. STUTSMAN. References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,027,175 Kallenbach Jan. 7, 1936 2,340,799 Depp Feb. 1, 1944 2,351,254 Elmendorf June 13, 1944 2,459,579 Noel June 18, 1949

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