US2663824A - Vapor-electric device - Google Patents

Vapor-electric device Download PDF

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US2663824A
US2663824A US144354A US14435450A US2663824A US 2663824 A US2663824 A US 2663824A US 144354 A US144354 A US 144354A US 14435450 A US14435450 A US 14435450A US 2663824 A US2663824 A US 2663824A
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metal
cathode
vapor
temperature
tube
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John L Boyer
August P Colaiaco
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Westinghouse Electric Corp
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Westinghouse Electric Corp
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Priority to ES0196560A priority patent/ES196560A1/es
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/50—Thermionic-cathode tubes
    • H01J17/52—Thermionic-cathode tubes with one cathode and one anode
    • H01J17/54—Thermionic-cathode tubes with one cathode and one anode having one or more control electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12542—More than one such component
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12583—Component contains compound of adjacent metal
    • Y10T428/1259—Oxide
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12597—Noncrystalline silica or noncrystalline plural-oxide component [e.g., glass, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12729—Group IIA metal-base component
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12778—Alternative base metals from diverse categories
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12937—Co- or Ni-base component next to Fe-base component
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12944—Ni-base component
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12951—Fe-base component

Definitions

  • ⁇ Our invention relates to vapor-electric devicesv or tubes, and particularly to low-arc-drop hotcathode arc-discharge devices using a Vaporizable discharge-metalv selected from the group consisting oi' potassium, rubidium and cesium.
  • Vaporizable discharge-metalv selected from the group consisting oi' potassium, rubidium and cesium.
  • These three metals form a more or less distinctive class by themselves, which may be described as the alkali metals havingY four, ve and six shells in the atomic structure, or the stable alkali metals having more than three shells.
  • the entire group or alkali metals consistsY of six elements, of which the iirst two and the last are readily distinguishable from the other three, with which our invention is particularly concerned.
  • the two lightest alkali metals, lithium (Li) and sodium (Na) are separated, in some periodic tables, .from the heavier light metals of the alkali-metal group (IA), as beingY distinctive because oi their electron-grouping;
  • the physical and chemical characteristics of these two lightest alkali-metals are also distinctively dierent from the group comprising potassium, rubidium and cesium.
  • Sodium has a minimum breakdown voltage which comes at too low a pressure-distance product for our purposes, as will be understood from explanations given later on; and it is also too active, chemically.
  • Lithium has a vapor-pressure which is much too low for our purposes, as this low Vapcr-pressure requires too high a temperature to obtain a practically usable vapor-pressure which is high enough to give a surliciently high current-density to be practical for our purposes.
  • Fe francium
  • a second requirement of a commercially usable power-type alkali-metal rectifier is that it shall combine a high current-density per unit of volurne of the space occupied by the cathode, with,V a high breakdown-voltage, or the ability to Withstand a reasonably large back-voltage during the non-conducting periods of the rectifier.
  • the ionization potential of a single gaseous atom or molecule is the voltage-drop through which an electron must be freely accelerated to acquire enough energy to be able to ionize the atom or molecule on collison, by removal Of one of its electrons.
  • the work function of a metal is the minimum energy which must be imparted to an electron inside of the metal, so that the electron can escape or be emitted from the surface of the metal at absolute zero temperature.
  • the General Electric Company in its United States patent to Hull, No. 2,489,891, granted November 29, 1949, showed an arc-discharge diode using a nickel cathode, with an arc-carrying vapor of cesium or rubidium, without many of our refinements, and using an insulator-to-metal seal in which the insulator was a ceramic, preferably one of the alumina ceramics or one of the magnesium-silicate ceramics, preferably joined to the metal by an allegedly new bonding material, referred to only as a manganese-molybdenum method, said to be described in an inaccessible patent-application.
  • This patent condemned previously known seals as being unsuitable for cesium-arc rectifiers, in the following language:
  • this expedient very greatly increases the electronemission, thus producing a higher current-density at a given voltage-drop, or a lower arcvoitage for a predetermined current-density of the electron-emission.
  • this expedient should be used with at least some, and probably all, of the high-work function cathode-metals which we prefer, as will be subsequently further described.
  • a grid-controlled hot-cathode vapor-electric arc-discharge device using a discharge-metal selected from the group consisting of potassium, rubidium and cesium.
  • the spacings between the various electrodes should preferably be small, in order to keep down the value of the arc-drop as much as possible, and keep the breakdown potential high.
  • the grid is thus close to the heated cathode, which operates at an electron-emitting temperature, and the grid is also heated by the play of the arc which passes through and around it.
  • the grid thus necessarily operates at a fairly high temperature, and it therefore involves a considerable problem to prevent the grid from emitting electrons, at its operating-temperature, in suflicient numbers to itself become a cathode, thus causing a backfire or failure of the tube.
  • it should be chosen just the opposite from the choice of the base-metal of the cathode, namely so that the surface-metal of the grid is a metal which has a work-function which is lower than the ionization potential of the varporizable discharge-metal which is being used. In this way, We prevent the grid from attracting, to its surface, a monatomic adhering layer of charged vaporizable-metal particles.
  • Another expedient is to reduce the operating-temperature of the grid, so as to thereby reduce its efficiency of emission.
  • the operating-temperature of the grid can be appreciably reduced by two practical means, namely the interposition of perforated heatshields between the hot cathode and the grid, and the use of a special construction of both the grid and (if used) the heat-shields, by having a relatively poor heat-absorbent surface on the side toward the cathode, which is heated, and a relatively good heat-radiating surface on the side toward the anode, which is cooled.
  • Figure 1 is a somewhat diagrammatic sectional elevation of a three-phase assembly of vaporelectric devices embodying our invention
  • Fig. 2 is a sectional elevation of a particular element or single-phase electronic tube embodying our invention, showing the same as a triode or grid-controlled tube;
  • Fig. 3 is a similar view of a modification showing a simplified discharge-device in the form of a diode
  • Fig. 4 is a detail section showing our improved glass-metal seal
  • Figs. 5 and 6 are sectional elevations, and Fig. 7 is an elevation, with parts broken away, showing Various methods of constructing a high-efciency cathode; and.
  • Figs. 8, 9 an-d l0 are detail sectional views ⁇ showing alternative structures for minimizing atmospheric leakage through the cathode-structure.
  • Fig. l three of our vapor-electric devices or tubes II are interposed between a direct-current powerycircuit or load-device
  • the star point of the zigzag secondary winding I5 constitutes the negative output terminal I2-, while the three phase-terminals of the zigzag-connected secondary winding I6 are connected to the respective anode-terminals I'I of the three tubes II.
  • the cathode-terminals I1 of the three tubes are all connected to the positive output-terminal H+.
  • the tubes are represented, schematically, as diodes. because the external gridcircuits may be conventional, and form no essential part of our present invention in some of its broadest aspects. However, we wish it to be understood that, in most actual commercial forms of embodiment of our invention, the tubes I I will be triodes, having one or more grids or dischargecontrolling means such as magnetic or electrostatic control-means.
  • the three rectifier-tubes II are shown in Fig. 1 as being mounted or enclosed within a heat-insulating cabinet I8, which is provided with a blower I9 for circulating a cooling fluid, preferably air, over the outsides, particularly the anodes 20, of the tubes.
  • a cooling fluid preferably air
  • the outer tank or container of our tube consists essentially of the anode 20.
  • This anode 20 is in the form of a cylindrical anode-member 2
  • the rectifier-tube I I is provide with a smaller-diameter cylindrical cathodemember 24, which is closed at its bottom end 25, and open at its top 26.
  • the closed bottom 25 of the cathode is spaced slightly above the closed bottom 22 of the anode.
  • cylindrical cathode-member 24 is considerably taller, or longer axially, than the cylindrical anode-member 24, so that a portion of the cylindrical cathodemember 24 extends up beyond the open top 23 of the cylindrical anode-member 2 I.
  • the iins 30 consist of a large nurnber of spaced discs or washers of thin metal, which are pressed onto the bottom end of the cylindrical cathode-member 24, or otherwise suitably secured thereto.
  • fins 30 which encircle the cylindrical cathodemember 24 can be much more securely fastened to the outer surface of said cylindrical cathodemember 24 than axially extending ns, for example, which are apt to fall on?, particularly if the cathode-member is made of a metal ⁇ with which it is difcult to make rm joints.
  • An essential part of any tube embodying our invention is a suitable form of insulator-to-metal seal, which is used to provide an enclosure-means which joins the open-ended tops of the cylindrical anode-member 2
  • insulator-to-metal seal which is used to provide an enclosure-means which joins the open-ended tops of the cylindrical anode-member 2
  • the insulator part of our seal is shown inthe form of a glass tube 33 which surrounds-the upstanding part of the cylindrical cathode-member 2li, in spaced relation thereto.
  • the glass tube 33 could be any other insulator, such as a ceramic tube, which might also be -used in making a successful insuiator-to-metal seal.
  • the top and bottom ends of the glass tube 33 are sealed to thin metal seal-forming tubes 3d' and 35 respectively.
  • the glass tube 33 may be made of a borosilicate glass
  • the top and bottom seal-forming metal tubes 34 and 35 may be made of a composition or alloy which fairly closely matches the thermal coefficient of expansion of the glass, a successful and'well-known metal of this nature being a composition of nickel, cobalt and iron.
  • the bottom seal-forming metal tube 35 is hermetically joined to the top of the cylindrical anode-member 2i, as by means of an annular metal header 35.
  • the top seal-forming metal tube 3f! is hermetically joined to the bottom of a cylindrical metal housing 31, as by means of another metal header 38.
  • the top of the metal housing 37 is hermetically joined to the outer surface of the upstandingvcylindrical cathode-member 2t, Vsomewhere near the top thereof, as by means of another metal header 39.
  • the cylindrical metal housing 31 is used as an expedient for providing a space within which can be mounted one or more grid-supporting insulators di, and a grid-terminal conductor or lead ft2.
  • the grid-terminal conductor 42 is brought outside of the electronic device or tube by means' of a suitable insulator-to-metal seal, which is illustrated as comprising a small glass tube i3 and top and bottom seal-forming metal tubes or caps L34 and 115, this grid-terminal seal being y preferably similar to the larger'seal 33, 3G, 35.
  • rine grid-supporting insulator or insulators M are each encircled by a metal band 136 which provides a bracket for supporting the top end of a cylindrical grid-supporting metal tube d?, which extends down between the upstanding cylindrical cathode-member 24 and the glass tube 33 of the main seal, in spaced relation to each.
  • the bottom end of the cylindrical grid-supporting metal tube di carries an annular bracket de, from the periphery of which is suspended a perforated cylindrical metal grid 50, which may be provided with a perforated bottom end-member l of the same material as the grid 50.
  • the grid 5E! is disposed between the nned cathode 2&1-30 and the anode 2 l.
  • a perforated metallic heat-shield 52 Interposed between the periphery of the cathode-fins 35 and the cylindrical grid 5! is a perforated metallic heat-shield 52 which is shown as being supported, from its top, by means of a flanged disc 53 which is carried by the cylindrical cathode-member 24.
  • the heat-shield 52 is also shown as being provided with a perforated bottom member 54, which is interposed between the bottom nn or plate 55 of the cathode-structure and the bottom end-member 5i of the grid. While we have shown only one heat-shield EQ2-5ft, it is to be understood, of course, that two or more of such shields could be used, preferably in spaced relation.
  • the heat-shield 52 is in relatively poor heat-transfer relation to the cathode-structure, being secured thereto, at only one spot, by means of the flanged disc 53, so that any thermally conducted heat, which passes from the cylindrical cathode tube 24 through the lhanged disc 53 to the top of the cylindrical heatshield 52, and then on down into the heat-shield, will have a long way to go in order to impart the heat of the cathode to the Shield in this manner.
  • a heat-shield may be provided or the main seal 33-35 As shown in Fig. 2, such a heat-shield is shown in the form of an imperforate metal tube 56 which extends up to the level of the glass tube 33.-, illustrated as being disposed between the cathode-tube :2d and the grid-supporting tube di', in spaced relation to each.
  • the bottom end of this imperforate tubular shield 55 is supported in a relatively poor heat-transfer relation with respect to the cathode-tube 2li, as by means of a flange 5l which makes contact with the top end of the cylindrical perforated heat-shield 52 between the cathode and the grid.
  • the kcomplete enclosure for our electronic device or rectifier-tube cornprises the closed-bottom tubular cathode-meinber 2d, the header 39, the cylindrical metal housing 3l, the header 38, the main seal ifl---S the header 35, and the closed-bottom cylindrical anode-member 2t.
  • the closed-bottom cylindrical cathode-member 24 thus constitutes a reentrant portion, sticking way down into the enclosed space of our electronic device or tube, so that the outer peripheral surface of this cylindrical cathode-member 2li is inside of the tube, while the inner surface or bore of this cylindrical cathode-member 2li is outside of the tube, being open to the surrounding atmosphere at the open top end of the said cylindrical cathode-member 2.
  • the enclosed space within our rectiner-tube may be evacuated by any convenient means.
  • the upper header1 39 which joins the cylindrical metal housing 3l to the outside wall of the cylindrical cathode-member 2d, is provided with a pumping-connection 5S, which is engaged by a tubing 59 through which the interior space within our rectifier-tube may be evacuated, after which the evacuating tubing 59 may be sealed olf, as indicated at et.
  • our preferred alkali metal is selected from the group consisting of potassium, rubidium and cesium. In the actual working of the tube, this metal is partly in the vapor or gaseous phase, and partly in the liquid phase, so that the vapor-pressure of the metal is determined by the temperaturel of the liquid portion of the metal.
  • rlhe vaporized portion of the metal serves the double function of carrying the arc-discharge within the tube, and also providing an adsorbed ionized coating or layer on the cathode, for greatly increasing the electronemissivity or current-carrying ability of the cathode, as will be subsequently described.
  • This vaporizable discharge-carrying alkalimetal when it is condensed to liquid form, may cling, in small globules, to any portion of the inner surface of the anode-member 2e, without requiring any particular place for it to go. in some instances, however, we may equip the anodestructure 20 with a perforated false bottom 6l to provide a space 62 thereunder, wherein one or more globules of the alkali-metal may accumulate, as indicated at 63.
  • a heating-means is provided, for predeterminedly heating the cathode-tube 24, and particularly the lower end of this tube, which is provided with the ns 30, and which constitutes the effective or active part of the cathode.
  • a resistancetype ca thode-heater 65 which is preferably carried by a top ilange 66 which is removably connectable to the open top of the tubular cathodemember 24, by means of a ring or flange 6l which is carried by said top end.
  • the top ange 66 of the cathode-heater 65 thus constitutes an endclosure for the open end of the cylindrical cathode-member 24.
  • this cylindrical cathode-member 24 may not be absolutely gas-tight, but may permit a small quantity of oxygen and hydrogen to slowly permeate, in a matter of months or years, through the walls of the cathode-tube, from the air into the interior of our electronic arc-.discharge device or tube. This leakage is apparently not an actual physical dilusion, but more a chemical diffusion or permeation.
  • any oxygen i or hydrogen which thus enters the arc-discharge tube through the walls of the cylindricalcathodemember 24 will instantly be absorbed by the alkali metal within the tube, which will unite therewith to forma chemical combination, but this combined alkali metal no longer functions as the vaporizable .discharge-metal within the tube. so that it is desirable to limit the quantity of oxygen and hydrogen which thus enters the arc-discharge device or tube, vthrough the walls of the cylindrical cathode-member 24.
  • any oxygen for example which leaks through the Walls ofthe cylindricalcathode-member .2.4, into the enclosedspace of our tube, simply robs or impoverishes theoxygen-content of the enclosed heater-space inside of the cylindrical cathodemember 24, using up the oxygentherein, which is not replaced, in anysubstantial volume, because of the approximately gas-tight gaskets 68, so that the slowvseepage of oxygen intothe evacuated space Within our arc-discharge tube is limited to the small amount of oxygen which was originally contained within the hollow cylindrical cathode-member'u, and this small amount of oxygen will usually be found to be quite tolerable by our arc-discharge device.
  • Our cathode-heatert is preferably mounted at the lower end of adownwardly extending cylindrical insulator 1I, which is supported by .a long bolt or rod 12, depending from the top ange or closure-member ,65.
  • a second resistance-type heater 13 on ⁇ this same cylindrical insulator ff'l'l, .disposed above the cathode-heater ⁇ 65, at a level suitable for heating the main seal-,34-33-35 and all ofthe upper portions of the evacuated tube, including the grid-supporting -insulators 4
  • Such condensation is to beavoided, in order to avoid the shortcircuiting of the insulators by a deposited film of condensed metal.
  • the cathode-heater 65 and the sealheater 13 are separate from each other, and separately controllable, as by having separate leads 16 and Tl, respectively, which may be brought out, through the top-closure 66, through suitable seals or insulators 'I8 which may be of ordinary design, as they are not subjected to any alkali-metal vapor.
  • this metal shall be capable of ionizing atoms of the vaporized alkali-metal which come into contact therewith, so that such ionizedatoms will adhere, by intermolecular electrostatic attraction, to the active surface of the cathode.r As has already been indicated, we believe that this requirement necessitates the choice of a cathode surface-inetal which has a work function which is higher than the ionization potential of the alkali metal which is being used.
  • the emission of electrons from an emitter is apparently affected by the past treatment of the emitter, and by sometimes very small traces of other substances, so that it is extremely difficult to obtain very precisely accurate repetitions of experimental data with regard to work functions, and we are also not sure that the apparent work function of our cathode-metal will not change with age.
  • the emission-efficiency of the cathode will also be affected by the thermionic-emission constant A of the cathode-metal.
  • Equation 2 also indicates the advantage of a metal having a low work function fp, in choosing the metal for the electron-emitting surface of the cathode, because the value of the coecient @41,608 WT is larger, at any given absolute temperature T, the smaller the value of the work function qb.
  • rIhe oxygen atoms are not necessarily in chemical combination with either the cathode-metal or the oxide metal of the ionized layer, although we are not sure on this point; and we do not know for sure whether the oxygen is in chemical union with either the base-metal or the superposed layer, or in chemical union to some extent with both metals, or whether it makes any difference which metal, if any, is in chemical union with the oxygen which is adsorbed on the surface of the cathode.
  • the cathode-metal must also have aV sufficiently low vapor-pressure, at the operatingtemperature of the cathode.
  • the vaporpressure of the cathode-metal is too high, at the operating-temperature of the cathode, an excessive quantity of the vapor of the cathode-metal permeates all over the space within the tube, and condenses more or less all over the inside surface of the tube, resulting eventually in the building up of a conducting nlm which short-circuits the necessary insulator or insulators which constitute parts or the enclosure-walls or the tube, and also resulting in some deposits of cathodemetal on the anode, on the grid, and on the heatshield.
  • the cathode-metal should not have a vapor-pressure higher than l3 microns of mercury at the operating-temperature of the cathode. Expressed a little difieren ly, we believe that the vapor-pressure of the cathode-metal should be less than -2 microns of mercury at a temperature of l000 C.
  • Tungsten. Copper High vapor-pressure and low melting point. Iron Molybdenum. obalt Tantalum..
  • Chromium, manganese and copper have been included in Table 2, even though they have too high a vapor-pressure for safe or satisfactory operation at a temperature of the order of 1000 C., and copper also has too low a melting-point for such operation, but if the maximum operating-temperature were considerably below 1000 C., say between 500 C. and 800 C., it may be that all three of these metals would be satisfactory, so far as either their vapor-pressure of their melting-point wouldv be concerned.
  • the metals which are listed in Table 2 are all available, either in sheet' (bulk) form, or as a surface-coating which could be applied, in one manner or another, to a less expensive or other- Wise more desirable base-metal, as is known in the metallurgical arts. There are certain precautions, of course, which must be observed in the handling of some of these metals. For example, beryllium is poisonous under some conditions but not so much so that it could not be successfully plated on a base-metal under satisfactory commercial factory-conditions; osmium forms a tetroxide which boils at C'.
  • Table 2 In using Table 2 as an aid in the selection of either a suitable cathode-metal or a suitable gridrnetal, reference should be made to Table 1, in which it is shown that the ionization potential of potassium is apparently 4.32 volts, while the ionization potentials of rubidium and cesium are apparently 4.16 and 3.83 volts, respectively.
  • chromium has too high a vapor pressure for the most satisfactory operation at a temperature approaching anywhere near l000 C., in any tube which is expected to have a reasonably acceptable length of life, according to commercial standards for power-tubes.
  • the work functions of the metals listed in Fig. 2 become more accurately available, they should be included in their proper place in Table 2, arranged in the order of descending values of the work functions.
  • the electron-emitting surface of the cathode should be of a high-melting-point metal, selected from Table 2, having a work function higher than 4.32 electron-volts.
  • These metals consist of iron, tungsten, ruthenium, osmium, iridium, rhodium, palladium, nickel, rhenium and platinum, and if the selection is limited to cathode-metals having a work function not more than about 0.6 volt higher than the potassium ionization potential of 4.32 volts, then the list of usable cathode-metals is limited to iron, tungsten, ruthenium, osmium, iridium, rhodium, palladium and nickel, and probably also including a borderline-list including rhenium and platinum. We believe that iron is a particularly desirable metal which has much to commend. it as a cathode-material.
  • rubidium is chosen as the discharge-metal, it is desirable to limit the choice of preferred cathode-metals to those high-melting-point metals, in Table 2, having a work function between the rubidium ionization potential of 4.16 volts and something like 4.76 volts.
  • These metals probably include cobalt, molybdenum, iron, tungsten, ruthenium, osmium, iridium and rhodium, and probably also a borderline-list including palladium and nickel. Iron may prove, in the long run, r
  • cesium is chosen as the discharge-metal, it is desirable to limit the choice of preferred cathode-metals to those high-melting-point, lowvapor pressure metals, in Table 2, having a work function between the cesium ionization potential of 3.88 volts and something like 4.48 volts.
  • This list apparently includes columbium, titanium, vanadium, tantalum, cobalt, molybdenum and iron, and probably also tungsten, ruthenium and osmium.
  • a preferred gridmetal is either molybdenum,.cobalt, tantalum, vanadium, titani1 im,vcolumbium, zirconium, hafnlum, thorium, and beryllium. For' a rubidiumvapor tube, the list of preferred grid-metals probably starts with tantalum.
  • Manganese is a rather doubtfully desirable grid-metal, because of its rather high vapor-pressure, whether potassium or rubidium is used as the discharge-metal.
  • the list of preferred grid-metals starts with zirconium, which, because of its relatively low cost (as compared to hafnium, thorium and beryllium), its non-toxicity (as contrasted with beryllium), and its high melting point, is a pre-eminently desirable gridsurface material for cesium tubes.
  • the heat-shield 52 or such portions thereof as are out of the arc-path within the tube (as for instance the upstanding heatshield 5t for the seal), should be made of a low- Work-function metal for the same reason as the grid, namely to reduce the danger of enough electron-emission to produce a cathode-spot.
  • the cathode When our ⁇ rectier-tube is operating, the cathode is maintained, by suitable energizaticn or control of the cathode-heater b5, at a suitable electron-emitting temperature for the highest obtainable eiiiciency or copiousness of electronemission. This will give the highest current for any given arc-drop, or the lowest arc-drop for any specied current.
  • the electronemissivity or current-strength at first increases, and then nnally begins to decrease, after reaching a maximum point, the decrease presumably corresponding to conditions under which the adhering surface-hlm or films on the cathode are beginning to boil off or to be driven olf by the thermal agitation of the molecules.
  • this temperature of maximum emissivity usually occurs at a temperature which is lower than the cathode-metal will stand.
  • the cathode-temperature of maximum emission is different for different cathode-metals, and it is also especially different for the different alkali metals, depending upon Whether potassium, rubidium or cesium is selected as the alkali metal to be used.
  • the cathode-temperature should be at least 860 C. In other cases, it is possible that cathode workingtemperatures of 760 C. or more may be used, but We would still prefer to choose a cathode-metal having a satisfactorily low vapor-pressure at SGO C., or whatever higher temperature is used for the cathode.
  • the cathode If the cathode is operated at too high a temperature, its vapor-pressure will increase to the point at which it gives off enough vapor of the cathode-metal to eventually foul up the other surfaces of the tube, where no cathode-metal is wanted, thus limiting the useful life of the tube. Whatever cathode-metal vapor is produced will condense ⁇ somewhere else onv the tube, on the insulators, on the grid, and onthe surface of the anode, etc.
  • Deposits of the cathode-metal are particularly objectionable on the insulators, where such deposits will short-circuit the insulators; and perhaps also on the grid, where any such deposits, because of the necessarily high operating-temperature of the grid, may cause cathx ode-spots and consequent back-firing.
  • the maximum allowable operating-temperatiuey oi the cathode must be limited, therefore, with a reasonable factor of safety, so that the useful life oi the tube will not be limited by this accumulation of deposits resulting from the condensation oi the vapor of the cathode-metal. This permissible cathode-temperature will Vbe dependent upon the vapor-pressure characteristics. of the cathodemetal.
  • the limiting safe cathode-tempera.- ture from the standpoint of vapor-pressure of the nichel, will be about 850 C. This is some EGG less than the temperature at which the vaporpressure of the cathode-metal (nickel) would be as much as 104 microns. On a similar basis, it is expectable that a reasonably long life, with a satisfactory margin of safety, so far as.
  • the Vaporpressure of the cathode-metal would be obtained with a tube in which the electronemitting surface of the cathode is platinum at about i300 C., or palladium at about 850 C., or iron at about 800 C., or osmium at about 1800" C., or rhodium at nearly 1400 C., or tungsten at possibly over 2200 C., or molybdenum at about 1%00" C., or cobalt at about 950 C., or zirconium at upwards of i200 C., or tantalum at possibly 2l00 C., or columbium at nearly i900D C.
  • These estimated temperature-figures, on the basis of cathodemetal vaporiaation, are subject to verification as a result of longliie-tests.
  • the vapor-pressure of the alkali metal is dependent upon which of the three preferred alkali metals is chosen, and it is also dependent upon 'the temperature at which the anode 20 is held.
  • the electron-emission of the cathode is more copious, the higher the anode-temperature, cause the higher alkali-metal Vapor-pressures which correspond to the higher anode-temperatures result in a larger number of alkali-metal atoms being present per cubic centimeter of the space within the tube, thus making' more alkalimetal atoms available for attachment to the surface of the cathode, and for ionization.
  • the breakdown voltage of the alkali-metal vapor goes down, in a curve which finally becomes fairly flat.
  • Most commercial rectifier-tubes are operated reasonably close to the breakdown limit oi the vapor, with a reasonable factor of safety included.
  • the breakdown voltage oi the vapor should be substantially morethan 2.5 times the 18 voltage of the direct-current circuit 12+, 12.-, to which the rectifier is connected'.
  • the breakdown voltage of the vapor within a tube is a function of the vapor-pressure ⁇ p, multiplied by the distance. d4 across which the breakdown voltage is being measured.
  • this distance ci' would be the distance between the grid 59 and the anode 2 I. Ir this distance is made as small as it is practicable to make it, all things being considered (so asA to reduce the total arcdrop within the tube), a distance of the.
  • the anode-temperature range which would give a breakdown voltage of somewhat more than 1500 volts, for satisfactory operation, would be about as follows, according to the alkali-metal which is chosen for the vapor. izable discharge-metal:
  • the total arc-drop will ordinarily be something like per cent of the ion,- ization potential of the vaporizable metal, or something like 5.8 volts for cesium, 6.2 volts for rubidium and 6.5 volts for potassium, or perhaps a little higher arc-drop than these voltages just stated.
  • these diierences. in the arc-drops for the different vaporlzable metals of our invention are perhaps not so important, but in 1GO-volt rectifier, these differences in the arc-voltage correspond practically to differences in the eiciency, so that they are much more im- ⁇ portant.
  • Vaporizable alkali metal whether it is to be potassium, rubidium or cesium, thus depends largely upon the operating-voltage and the importance which is to be given to the eiiiciency, as well as the size o1' rectifier which will be required for obtaining any given currentcarrying capacity.
  • potassium seems to vbe the best of the three comparable alkali-metals, but our experience with these ⁇ tubes is not suihcient, at present, to enable us to give a final answer, which is free of all guess-work based upon deductions from our tests thus far.
  • alkali metals including the three of our choice, are very active chemically, and have an especially high anity for oxygen, so that they attack most oxides and other oxygencontaining compounds such as silicates.
  • the alkali-metals thus attack most glasses and most ceramics, but when the available insulating materials (glasses and ceramics) are properly chosen, the rate at which they are attacked is so slow, and the penetration of the attack is so small, that such attacks by the alkali metals which we use do not seriously limit the life of our tube, particularly when a proper choice is made, using alkali-resistant glazes and ceramics or ceramic coatings.
  • various sodium-resistant glazes are known, which are used to coat the inside glass surfaces of sodium-vapor lamps.
  • thermodynamics of reactions at nonstandard temperatures that is, reactions at temperatures other than 25 C.
  • the theory is subject to equations involving a knowledge of the so-called free-energy of the substances at the temperature at which the reaction is to be tested, that is, at the temperature at which it is desired to determine whether the available oxygen of an oxide will attach itself to one metal or the other.
  • free energies of most metal oxides particularly at non-standard temperatures.
  • chromium seems to be pretty close to a borderline metal, whose oxide may not be quite able to forever resist reduction by the Vapor of any one of the three chosen alkali-metals, potassium, rubidium and cesium; but the deleterious reaction, if any, which exists in the case of chromium, is so slow that a seal having a chromium-surfaced sealing-metal has a life at least of the order of 2,000 to 20,000 hours in the presence of such vapors at the operating temperature of the seal.
  • the other sealing-metals which we have mentioned have much longer lives, the exact actual lives of which have not yet been ascertained.
  • the chosen metal will be used as a solid piece, or in sheet-form, whereas, in other cases, the chosen metal will be used as a surface-coating, properly prepared on an underlying metal having a lower cost, 01 having better characteristics which are useful in other respects, such as mechanical strength at the operating temperature, imperviousness to gaseous diiusion, a better coeicient of thermal expansion, etc.
  • the thickness of the chromium plating on the inside, or vapor-exposed side, of the sealing metal should preferably be of the order of 1/0 of the total thickness of the sealing metal.
  • the surface of the chromium plating When the surface of the chromium plating is lightly oxidized, it forms a thin coating of chromic oxide, CrzOs, which is readily wetted by glass. It is best to rst glaze this chromic-oxide surface with thin layer of a bonding-glass, before undertaking to unite the same, by heat and pressure, with the glass part, 33 or 43, of the seal.
  • Beryllium is best deposited as a surface-coating on an underlying metal by vaporizing the beryllium and letting the vapor condense on the i underlying metal in a vacuum. Beryllium can also be coated on the underlying metal by electrolytic deposition from a fused salt bath, such as a bath containing one part of sodium chloride, one part of sodium fluoride, and two parts of beryllium fluoride at about 756 C.i25 C.
  • a fused salt bath such as a bath containing one part of sodium chloride, one part of sodium fluoride, and two parts of beryllium fluoride at about 756 C.i25 C.
  • the beryllium coating after being deposited, is then rst diffused into the underlying metal, and nally lightly surface-oxidized, by the combination of a hot dry-hydrogen treatment, followed by a hot wet-hydrogen treatment, as has been described for the case of chromium.
  • zirconium is best deposited as a surface-coating on an underlying metal by condensation in a vacuum.
  • the zirconium layer should be diffused into the underlying metal, as in the case of chromium or beryllium, but it is unnecessary to use the peroxidization step, as the oxidation which is inherent in the glass-sealing process is quite suncient for providing enough zirconium oxide for bonding with the glass.
  • zirconium can also be used in sheet form, without having to coat it on an underlying metal, as it has a. coecient of thermal expansion which is readily matchable with available glasses, so that it can be used, in the solid form, as distinguished from the plated form, as the metallic part of a glass-to-metal seal.
  • this arc-drop is less than 1 volt for low currents, and it increases nearly linearly to a voltage which is about equal to the ionization potential of the vapor, for high currents.
  • the current-rating of the tube is also increased as the anode-temperature is increased, but the back-voltage that the tube can withstand decreases with increasing anode-temperatures, and that is why the anode-temperature which is chosen as the operating-temperature is always the highest temperature which will enable the tube to safely withstand the back-voltage which is impressed thereon during the non-conducting periods.
  • ns such as 30, on the cathode, is quite advantageous, not only in producing a cathode which has a large area for electron-omission, without requiring an inordinately large tube, but also in providing a cathode which has a relatively small effective heat-radiating area, in proportion to its electron-emitting area, thus reducing the amount of energy which needs to be put into the cathode-heater 65.
  • the amount of heat-input into the cathode can also be minimized, by designing the internal, or electron-emitting, surfaces of the finned cathode so as to have highly polished surfaces, thus reducing the heat-emissivity of these surfaces.
  • the cathode has a relatively poor heat-radiating or heat-transfer surface on the side toward the 'grid and-the' anode;
  • the outer surface of the cathode that is, the surface which is exposed to the outside atmosphere, Which, in our illustrateddevice, is the inside surface or bore of the cathode-tube 2t, should advantageously be roughened, so that it acts as a relatively good heat-absorbing surface for absorbing the heat of the cathode-heater 65.
  • the heat-shield 52 particularly where the heatshield is in poor conductive heat-transfer relation to the cathode.
  • the surfaces of these elements, on the side toward the heated cathode, should be highly polished, so as to reduce their heat-absorbent ability to a minimum, while the surfaces on the side toward the cooled anode should be roughened, so as to be relatively good heat-radiating surfaces.
  • the inner surface of the anode 2! should best be made with a roughened surface, in order to present a good heat-transfer surface toward the grid, so as the more effectively to cool the grid.
  • the inner surface of the anode should preferably be polished, in order to reduce its cooling effect on the hot cathode, thus reducing the amount of heating-energy which must be put into the cathode-heater in order to maintain the cathcde at the desired operating-temperature.
  • anode Since the anode operates at a relatively cool temperature, difficulties are not commonly encountered with respect to any material amount of electron-emissivity (which would produce'a danger of backring) or With respect to low meltingpoints of any metals Which would commonly be considered for the tube-construction.
  • An advantage of our preferred structural assembly is that the grid-assembly is mounted as a unit on the cathodestructure, before the latter is inserted into the anode-assembly or outer housing of the tube.
  • All of the insulators, such as 33 and d3, which are a part of the enclosure or housing of the tube, and which are thus exposed to the alkali-metal vapor within the tube, should be held to a temperature of 256 C. or higher. In fact, Whatever may be the operating-temperature of the anode of any particular tube, these insulators should be kept at a temperature which is safely higher than the anode-temperature, so as to avoid the possibility of the alkali-metal vapor condensing and depositing on the inner surfaces of the insulators.
  • the cathodetube 2d has applied thereto a plurality of spacedapart Washers or ns 3@ of the same cathodemetal.
  • the bore 8B of these iins 39] is initially slightly smaller than the outer diameter of the central tubular cathode-member 2li, and the fins 3 are assembled with a press fit. If a non-elastic metal, such as nickel, is used for the cathode, it is sometimes found that these hns 3i? have a tendency to be, or to become, loose on the cathode-tube 24.
  • the fins may be firmly anchored in piace by a coating of a relatively thin, yet suificiently thick, layer of the same cathode-metal (such as nickel, for example), so that the cathode-hns 39 are rigidly held in place on the cathode-tube 2d.
  • a coating of a relatively thin, yet suificiently thick, layer of the same cathode-metal such as nickel, for example
  • the cathode-tube 24 can be made of a substantial thickness, and its peripheral surface may be formed or turned, as by means of a cutting tool (not shown), to provide ridges or ns 82 which are integral with the cathode-tube 2li itself.
  • the cathode-heater 55 is the incst vulnerable or short-lived portion of the device, and that is the reason why We have mounted this heater on a removable closure or cap so that the heater is substantially independent of structure of the arc-discharge device, and hence can be replaced from time to time, thus substantially extending the useful life orf our device.
  • the gas-tight gaskets 68 may be used, as shown in Fig. 2, so as either to prevent entrance of the atmosphere, or to retain a reduced-pressure gas-filling in the hollow tubular cathode-body 24.
  • This reduced pressure may be readily accomplished by energizing the heaters 65 and/or 13, to expand the gases within the cathode heater-chamber, after which the gaskets 68 are pulled down tight to prevent any further ingress of atmospheric gases; or the space may be substantially evacuated.
  • the seal-heater 13 and the cathode-heater 65 have a common junction 8S to the cap 66, and the heater-terminals 'l1 and 16 are brought out in gas-tight relation through normal glass-metal seals 18.
  • FIG. 9 A further method of eliminating the gases in the heater-chamber within the tubular cathodeportion 24 is disclosed in Fig. 9, where a needlevalve 88 is applied to the heater-chamber, so that the gaskets 68 may be pulled down tight before energizing the heater-elements 65 or 13, and then, after the heater has been energized, and has expelled a large portion of the atmosphere within the heater-chamber, the valve 88 may be closed to maintain a low pressure.
  • the heater-chamber may be iilled with a gas, preferably a gas having a high thermal conductivity, such las nitrogen, argon, krypton, neon or helium, which will not permeate through the offending cathode-metal, such as nickel.
  • a gas having a high thermal conductivity such las nitrogen, argon, krypton, neon or helium, which will not permeate through the offending cathode-metal, such as nickel.
  • control-grid may be omitted, where current-control is not desired, particularly for high-current, low-voltage operation.
  • a reservoir or reservoirs for the liquid alkali vmetal may be provided by one or more holes or depressions ,90, drilled in the bottoni 22 of the anode 20, rather than using the false bottom l(il of Fig. 2.
  • a heater-control having one source of substantially constant potential, and having another source of a potential which is dependent upon the load through the device.
  • a variable heating current for the cathode-heater e5 by means of a step-down or low-voltage transformer Si, the primary of -which is connected to an auxiliary supply-transformer 92 in series with a variable saturable reactor 93, the saturating current of which is the load-current of the vapor-electric device.
  • the cooling of the anode 20 may also be caused to be substantially dependent upon the heat-now from the cathode 24-30 to the anode 20, which is again substantially dependent upon the loadcurrent.
  • the speed of our blower I9 which drives cooling air over or around the anodes 20, is controlled by the variable voltage which energizes the primary circuit of the cathode-heater transformer el. rFhis variable voltage is applied to the blower-motor 94 by means of a rectier-bridge S5.
  • receives a voltage which increases with the load-current, so that the heating of the cathode 24 increases suinciently to compensate for the heat carried away from the cathode by the electrons nowing therefrom.
  • variable rheostatic controls such as a variable resistor 96 in series with the blowermotor, another variable resistor 91 (or other variable impedance) in series with the cathodeheater terminal 15, and still another variable resistor 98 which is connected between the sealheater rterminal 'il and a step-down or lowvoltage transformer 99 which is shown as being energized from the secondary of the auxiliary supply-transformer 92 in Fig. 1.
  • the variable resistors 9S, 91 and 98 may be manually or thermostatically controlled for maintaining predetermined operating-temperatures in conformity with our invention.
  • a vapor-electric device comprising spaced electrodes between which an electric current can ow, and an enclosure-means including an insulator-tc-metal seal, said device including a quantity of a vaporizable metal selected from the group consisting of potassium, rubidium and cesium, and further characterized by the metal part of said insulator-to-metal seal having a lightly oxidized vapor-resistant surface composed of a metal having a suciently high melting point to enable the formation of said seal, and having an oxidized surface, said seal-metal being one of the chemical group of metals whose oxides have a relatively high negative free-energy, as compared to the negative free-energy of the oxideA of said vaporizable metal.
  • a vapor-electric device comprising spaced electrodes between which an electric current can ovv, and an enclosure-means including an insulator-to-metal seal, said device including a quantity of a vaporizable metal selected from the group consisting of potassium, rubidium and cesium, and further characterized by the metal part of said insulator-to-metal seal having a lightly oxidized vapor-resistant surface composed of a metal selected from the group consisting of beryllium, zirconium, chromium and titanium for resisting reduction by said vaporizable metal at the operating-temperature of the seal.
  • a vapor-electric device comprising spaced electrodes between Which an electric current can flow, and an enclosure-means including an insulator-to-metal seal, said device including a quantity of a vaporizable metal selected from the group consisting of potassium, rubidium and cesium, and further characterized by the metal part of said insulator-to-metal seal having a lightly oxidized vapor-resistant beryllium surface for resisting reduction by said vapcrizable metal at the operating-temperature of the seal.
  • a hot-cathode vapor-electric arc-discharge device comprising a iinned cathode having a large electron-emitting surface Within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of a discharge-metal Within said device, said discharge-metal being selected from the group consisting of potassium, rubidium and cesium, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperau ture, cooling-means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate Working-temperature, said device being characterized by said cathode having an electron-emitting surface selected from the group of metals having a work function higher than the ionization potential of the discharge-metal, and also having an adsorbed surface-layer of oxygen
  • a hot-cathode vapor-electric arc-discharge device comprising a inned cathode having a large electron-emitting surface Within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of a discharge-metal Within said device, said dischargemetal being selected from the group consisting of potassium, rubidium and cesium, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, coolingmeans for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by said cathode having an electron-emitting surface selected from the group of metals having a work function higher than the ionization potential of the discharge-metal, and also having a vapor-pressure sumciently lovv to avoid
  • a hot-cathode vapor-electric arc-discharge device comprising a finned cathode having a large electron-emitting surface within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of a discharge-metal Within said device, said discharge-metal being selected from the group consisting of potassium, rubidium and cesium, heating-neans for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling-means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface Which determines the Working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate Working-temperature, said device being characterized by said cathode having an electron-emitting surface selected from the group of metals having a work function higher than the ionization potential of the discharge-metal by an amount between the limits of zero and about 0.6
  • a hot-cathode vapor-electric arc-discharge ldevice comprising a finned cathode having a large electron-emitting surface within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of potassium within the device, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate Working-ternperature, said device being characterized bysaid cathodehaving an electronemitting surface selected from the group of metals consisting of iron, tungsten, ruthenium, osrnium, iridium, rhodium, palladium and nickel.
  • a hot-cathode vapor-electric arc-discharge device comprising a finned cathode having a large electron-emitting surface within a relatively small volume, an anode, enclosure-means including an insulator-to-inetal seal, a quantity of rubidium within the device, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the Working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by said cathode having an electronemitting surface selected from the group of metals consisting of cobalt, molybdenum, iron, tungsten, ruthenium, osmium, ridium, rhodium, palladium and nickel.
  • a hot-cathode vapor-electric arc-discharge device comprising a nned cathode having a large electron-emitting surface within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of cesium within the device, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling-means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal., and means for maintaining the seal at an intermediate worling-temperature, said device being characterised by said cathode having an electronemitting surface selected from the group of metals consisting of columbium, titanium, vanadium, tantalum, cobalt, molybdenum, iron, tungsten, ruthenium and osmium.
  • a hot-cathode vapor-electric arc-discharge device comprising a finned cathode having a large electron-emitting surface within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of a discharge-metal within said device, said discharge-metal being selected from the group consisting of potassium, rubidium and cesium, heating-means for predeterminedly heating the cathy ode to a suitable electron-emitting temperature, cooling-means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by said cathode having an electron-emitting surface of iron.
  • a hot-cathode vapor-electric arc-discharge device comprising a nned cathode having a large electron-emitting surface within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of potassium within theY device, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface Which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by said cathode having an electron-emitting surface of iron.
  • a hot-cathode vapor-electric arc-discharge device comprising a finned cathode having a large electron-emitting surface within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of rubidium within the device, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by said cathode having an electron-emitting surface of iron.
  • a hot-cathode vapor-electric arc-discharge device comprising a nned cathode having a large electron-emitting surface within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of cesium within the device, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, coolingmeans for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by said cathode having an electron-emitting surface of iron.
  • a hot-cathode vapor-electric arc-discharge device comprising a finned cathode having a large electron-emitting surface within a relatively small volume, an anode, enclosure-means including an insulator-to-metal seal, a quantity of a discharge-metal within said device, said discharge-metal being selected from the group consisting of potassium, rubidium and cesium, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling-means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by said cathode having an electron-emitting surface selected from the group of metals having a Work function higher than the ionization potential of the discharge-metal, said device being further characterized by having one or more perforated heat
  • a vapor-electric arc-discharge device comprising spaced electrodes between which an electric current can flow, and a quantity of a vaporizable metal therein, selected from the group consisting of potassium, rubidium and cesium, said device including a substantially non-emitting solid-metal member within the device, enclosure-means including an insulator-to-metal seal, and means for maintaining the seal at a Working-temperature higher than the workingtemperature of the liquid portion of the Vaporizable metal, said device being characterized by at least a.
  • said substantially non-emitting member having a' surface selected from the lgroup of metals having a work function lower than the ionization potential of the vaporizable metal, and having a melting point higher than the maximum operating temperature of said substantially non-emitting electrode.
  • a vapor-electric arc-discharge device comprising spaced electrodes between which an electric current can flow, and a quantity of potassium therein, said device including a substantially non-emitting solid-metal member within the device, enclosure-means including an insulator-tometal seal, and means for maintaining the seal at a working-temperature higher than the working-temperature of the liquid portion of the potassium, said device being characterized by at least a portion of said substantially non-emitting member having a surface selected from the group of metals consisting of molybdenum, cobalt, tantalum, vanadium, titanium, columbium, zirconium, hafnium, thorium, and beryllium.
  • a vapor-electric arc-discharge device comprising spaced electrodes between which an electric current can flow, and a quantity of rubidium therein, said device including a substantially non-emitting solid-metal member Within the device, enclosure-means including an insulator-tometal seal, and means for maintaining the seal at a working-temperature higher than the Working-temperature of the liquid portion of the rubidium, said device being characterized by at least a portion of said substantially non-emitting member having a surface selected from the group of metals consisting of tantalum, vanadium, titanium, columbium, zirconium, hafnium, thorium, and beryllium.
  • a vapor-electric arc-discharge device comprising spaced electrodes between which an electric current can flow, and a quantity of cesium therein, said device including a substantially nonemitting solid-metal member within the device, enclosure-means including an insulator-to-metal seal, and means for maintaining the seal at a working-temperature higher than the workingtemperature of the liquid portion of the cesium, said device being characterized by at least a portion of said substantially non-emitting member having a surface selected from the group of metals consisting of zirconium, hafnium, thorium, and beryllium.
  • a vapor-electric arc-discharge device comrising spaced electrodes between which an electric current can flow, and a quantity of cesium therein, said device including a substantially nonemitting solid-metal member Within the device, enclosure-means including an insulator-to-metal seal, and means for maintaining the seal at a working-temperature higher than the workingtemperature of the liquid portion of the cesium, said device being characterized by at least a portion of said substantially non-emitting member having a surface of zirconium.
  • a hot-cathode vapor-electric arc-discharge Cil 'device comprising a iinned cathode having a large electron-emitting surface within a relatively small volume, a grid, an anode, enclosure-means including an insulator-to-metal seal, a quantity of a discharge-metal within said device, said discharge-metal being selected from the group consisting of potassium, rubidium and cesium, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling-means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by said cathode having an electron-emitting surface selected from the group of metals having a work function higher than the ionization potential of the discharge-metal, and having a melting
  • a hot-cathode vapor-electric arc-discharge device comprising a finned cathode having a large electron-emitting surface within a relatively Sinai volume, a id, an anode, enclosure-means including an insulatcr-to-metal seal, a quantity of a discharge-metal within said device, said discharge-metal being selected from the group consisting ef potassium, rubidium and cesium, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling-means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by Said cathode having an electron-emitting surface selected from the group of metals having a work function higher than the ionization potential of the discharge-metal, and having
  • a hot-cathode vapor-electric arc-discharge device comprising a nnned cathode having a large electron-emitting surface Within a relatively small volume, a grid, an anode, enclosure-means including an insulator-to-metal seal, a quantity of a discharge-metal within said device, said discharge-metal being selected from the group consisting cf potassium, rubdium and cesium, heating-means for predeterminedly heating the cathode to a suitable electron-emitting temperature, cooling-means for predeterminedly cooling the anode to a substantially non-emitting temperature and for providing a condensing-surface which determines the working vapor-pressure of the discharge-metal, and means for maintaining the seal at an intermediate working-temperature, said device being characterized by said cathode having an electron-emitting surface selected from the group of metals having a work function

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  • Lasers (AREA)
  • Resistance Heating (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
US144354A 1950-02-15 1950-02-15 Vapor-electric device Expired - Lifetime US2663824A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
NL159006D NL159006C (en(2012)) 1950-02-15
US144354A US2663824A (en) 1950-02-15 1950-02-15 Vapor-electric device
DEW5066A DE924281C (de) 1950-02-15 1951-01-31 Elektrisches Dampfentladungsgefaess
ES0196560A ES196560A1 (es) 1950-02-15 1951-02-14 Un dispositivo eléctrico de vapor

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US144354A US2663824A (en) 1950-02-15 1950-02-15 Vapor-electric device

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US2663824A true US2663824A (en) 1953-12-22

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DE (1) DE924281C (en(2012))
ES (1) ES196560A1 (en(2012))
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3034971A (en) * 1958-09-09 1962-05-15 Gen Electric Process for producing an electrically insulated conductor
US3252039A (en) * 1962-07-23 1966-05-17 Gen Electric Electric discharge device
US3579031A (en) * 1967-06-07 1971-05-18 Xerox Corp Zero arc drop thyratron
US20140355971A1 (en) * 2013-05-30 2014-12-04 Osram Sylvania Inc. Infrared Heat Lamp Assembly

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1924375A (en) * 1930-10-09 1933-08-29 Gen Electric Cathode structure for thermionic devices
US1924319A (en) * 1930-10-09 1933-08-29 Gen Electric Cathode structure for thermionic devices
US2011372A (en) * 1931-12-18 1935-08-13 Siemens Ag Glow-discharge vessel filled with gas or vapor
US2365958A (en) * 1943-07-10 1944-12-26 Electric Arc Inc Continuous arc welding system
US2489891A (en) * 1948-12-27 1949-11-29 Gen Electric Cesium electric discharge device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1924375A (en) * 1930-10-09 1933-08-29 Gen Electric Cathode structure for thermionic devices
US1924319A (en) * 1930-10-09 1933-08-29 Gen Electric Cathode structure for thermionic devices
US2011372A (en) * 1931-12-18 1935-08-13 Siemens Ag Glow-discharge vessel filled with gas or vapor
US2365958A (en) * 1943-07-10 1944-12-26 Electric Arc Inc Continuous arc welding system
US2489891A (en) * 1948-12-27 1949-11-29 Gen Electric Cesium electric discharge device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3034971A (en) * 1958-09-09 1962-05-15 Gen Electric Process for producing an electrically insulated conductor
US3252039A (en) * 1962-07-23 1966-05-17 Gen Electric Electric discharge device
US3579031A (en) * 1967-06-07 1971-05-18 Xerox Corp Zero arc drop thyratron
US20140355971A1 (en) * 2013-05-30 2014-12-04 Osram Sylvania Inc. Infrared Heat Lamp Assembly
US10264629B2 (en) * 2013-05-30 2019-04-16 Osram Sylvania Inc. Infrared heat lamp assembly

Also Published As

Publication number Publication date
NL159006C (en(2012))
ES196560A1 (es) 1953-02-16
DE924281C (de) 1955-02-28

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