US1932025A - Electrode positive column lamp - Google Patents

Electrode positive column lamp Download PDF

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Publication number
US1932025A
US1932025A US417091A US41709129A US1932025A US 1932025 A US1932025 A US 1932025A US 417091 A US417091 A US 417091A US 41709129 A US41709129 A US 41709129A US 1932025 A US1932025 A US 1932025A
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US
United States
Prior art keywords
electrode
thorium
electrodes
hollow
comprised
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Expired - Lifetime
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US417091A
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English (en)
Inventor
Thomas Charles Hastings
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Westinghouse Lamp Co
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Westinghouse Lamp Co
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Publication date
Application filed by Westinghouse Lamp Co filed Critical Westinghouse Lamp Co
Priority to US417091A priority Critical patent/US1932025A/en
Priority to FR708351D priority patent/FR708351A/fr
Priority to GB38992/30A priority patent/GB376220A/en
Application granted granted Critical
Publication of US1932025A publication Critical patent/US1932025A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/067—Main electrodes for low-pressure discharge lamps
    • H01J61/0675—Main electrodes for low-pressure discharge lamps characterised by the material of the electrode

Definitions

  • This invention relates to electric devices of the gaseous conduction type and more particularly to gas discharge devices in which the discharge is maintained between relatively cold electrodes.
  • Another object of this invention is to provide an electrode for a gaseous discharge device operable in said device at relatively high current densities and relatively low electrode potentials.
  • Another object of this invention is to provide a gaseous discharge device which may be operated at relatively high electrode current densities and relatively low electrode potentials.
  • Another object of this invention is to provide 3 means for obtaining thermionic electron emission from an electrode in a gaseous discharge device without incandescing the same by electrical energy from an auxiliary circuit.
  • the electrode space charge sheath and in particular the oathode space charge sheath may be in part neutralized or eliminated by providing an electrode which is thermionically active, the negative stream of electrons flowing therefrom serving in efiect to lower the electrode potential required to bring a positive ion to the electrode surface. Under such conditions higher electrode current densities may be employed than have been heretofore permissible with relatively cold type electrodes.
  • a second disadvantage is that such an electrode, being operated at a relatively high temperature is subject to the same sputtering eflects heretofore obtained with solid relatively cold type electrodes, and due to ,the relatively small size thereof, a materially shorter operating life 100 and efllciency than with the solid cold type electrodes is obtained.
  • the electrode at least in of thermionically active material, that 3'. may apply to the electrode a sumciently high currentdensity to efiect substantially an incandescence oi the surface of that portion thereof which is subjected to ion bombardment, to a temperature at which the electrode'material emits thermionic electron emission, which emission may thereby be utilized in improving the operating characteristics of the device.
  • the discharge device is comprised of a long tubular glass envelope 1 which is relatively small in diameter with respect to its length, having enlarged ends 2 within which are enclosed electrodes 3 integral with support incinber 4 passing through press 5 to make electrical connection with current carrying conductors 8.
  • the narrow tubular portion 1 is shaped in the form of a letter N and the enlarged portions 2 are bent at right angles to the plane of the narrow tubular portion 1.
  • Fig. 2 is a cross sectional view of the same showing the hollow tubular feature onthe electrode 3 and the relative depth and diameter of the recessed portion 7 therein.
  • I preferably comprise the electrode 301 .a solid coherent mass of metal, and drill the recessed portion '1 therein in any convenient manner.
  • electrode 8 may be,
  • a highly reactive thermionically active rare refractory metal such as thorium, zirconium, uranium and the like which metals are preferably prepared by the process set forth in copendlng application Serial No. 717,949 filed June 5, 1924 by J. W. Marden et al., entitled Ductile thorium and the method of making the same, which application is assigned to the same assignee as the present invention.
  • the solid thorium metal body for example, prepared as by the above identified copendlng application is substantially shaped to the form of a hodow cylindrical body having one end open which form may be most readily obtained by a hole in one end of a cylindrical mass of thorium, the specific size of the electrode and relative size and depth of the opening therein being dependent upon the particular discharge device within it is to be incorporated, the desired characteristics oi the electrode, the gas pressure employed, the desired electrode voltages, and the like factors.
  • a common size electrode which is useful in the type device illustrated in Fig. 1 is approximately .15 inches in diameter, about inches in length, in one end of which is drilled a hole of about .075 inches diameter to a depth of about inch.
  • This electrode is then mounted in any convenient manner upon the electrode support wire 4 and sealed into the glass envelope 1 of the device in the usual manner.
  • the device is then exhausted by mechanical exhaust means, the glass envelope 1 being baked out for a period of time to eliminate deleterious adsorbed and absorbed gases.
  • the usual inert or monatomic gas filling is admitted and the device sealed oil.
  • the gases should first be thoroughly freed of deleterious atmospheric gases by well known prior art practices.
  • the device is then subjected to a s asoning operation wherein the electrodes are subjected to positive ion bombardment at relatively low current densities thereby effecting substantial cleanup of residual atmospheric gases within the device, the thorium electrodes acting as a "getter" for such gases. While it is expedient from a manufacturing standpoint to effect a prior purification of the inert gases, thorium electrodes will eifect the clean-up of relatively large amounts of atmospheric gases.
  • FIG. 3 An alternative electrode structure is shown in Fig. 3 wherein the hollow tubular electrode 3 is enclosed or coated superficially with an electrical- 1y insulating coating 9, which may be of dissimilar refractory metal oxide material than the metal of the electrode, such as for example, hollow tubular electrode 3 may be comprised of zirconium, or titanium and coating 9 may be comprised of thorium oxide.
  • an electrical- 1y insulating coating 9 which may be of dissimilar refractory metal oxide material than the metal of the electrode, such as for example, hollow tubular electrode 3 may be comprised of zirconium, or titanium and coating 9 may be comprised of thorium oxide.
  • Another specific combination of electrode material that may be employed in the practice of my invention is a thorium electrode coated superficially with refractory oxides of zirconium aluminum, magnesium and the like.
  • I may comprise the hollow electrode 3 of a highly refractory metal such as tungsten and coat the interior surface of the hollowed out portion with thermionically active material, such as thorium or I may incorporate the same as an alloyed or admixed constituent of the same.
  • a highly refractory metal such as tungsten
  • thermionically active material such as thorium
  • I may incorporate the same as an alloyed or admixed constituent of the same.
  • the test upon which these curves are based was made upon two identical glow discharge devices in one of which there was a solid electrode of thorium approximately inches long by .15 inches diameter, and in the other the same sized thorium electrode hollowed out or drilled a depth of one half inch with a hole approximately ,.076 inches diameter.
  • the electrodes were incorporated in opposite ends of a inch glass tubing a distance of 13 mm. apart and a gas pressure of about 10.3 mm. neon introduced.
  • the curves are identified as solid electrode and drilled electrode.
  • the glow discharge device incorporating the solid electrodes has a break down voltage of about 280 volts, and an operating voltage of about 1'70 volts.
  • the device incorporating the hollow electrode has a break down voltage of about 270 volts and an operating voltage of about 155 volts.
  • the electrode space charge sheath of a solid electrode entirely surrounds or encloses the electrode and it requires a certain minimum voltage for a positive ion to penetrate this sheath.
  • Increased electrode current density usually increases the depth of this electrode sheath and also requires increased voltages to penetrate the same. Any voltage in excess of the amount necessary to penetrate the sheath appears to impart added velocity to the positive ion, which is dissipated as heat at the surface of the electrode upon impact of the positive ion thereto and serves substantially as a means of raising the temperature of the electrode.
  • the positive ion bombardment gradually raises the temperature of the electrode to a point where electron emission is obtainable therefrom, with the resulting slight depression in the curve at A indicating increased efilciency.
  • the sputtering of the electrode is relatively high and the effective operating life of the device is materially shortened. It is found, however, that the beneficial effect of the thermionic emission is substantially lost at higher potentials as the depth of the cathode space charge sheath increases with increased current density and the thermionic emission from the surface of the electrode is insufficient in amount to materially reduce the cathode drop in potential at this higher current density.
  • the operating life of the device at these higher ciu'rent densities is materially shortened.
  • the cathode fall in potential increases initially with increased current density in an identical manner as when a solid cathode is employed.
  • the usual increase in cathode drop in potential with increased current density reaches a maximum, and with further increase in current density a decided drop in operating potential is obtained. This is believed due to the efi'ect of limiting the cathode space charge sheath within the confines of the recessed portion of the electrode. As a result of this-limitation a certain maximum voltage only is required to penetrate this sheath.
  • Electrode potentials in excess to that required to penetrate the sheath are converted into heat energy at the inner surface of the electrode through bombardment by positive ions, coining local thermionic emission spots, photo-electric effects, or by the use of the specific thermionically active material certain electrical effects not heretofore obtainable are developed.
  • the principal effect of thermionic emission as heretofore noted is to break down the electrode space charge sheath by the emission of a stream of negative electrons.
  • the cathode drop in potential across the device in directly efiected and a decrease thereof is obtained.
  • This decrease in cathode drop in potential continues to point D which is at approximately 110 milliamperes and the curve then flattens out and continues to remain so. It is believed that under these operating conditions the maximum neutralization of the space charge sheath by thermionic emission from the recessed portion of the electrode has been obtained. At currents much above 110 milliamperes the electrode sputtering is so great that the life of the device is materially shortened.
  • the electrode comprised substantially of refractory or substantially non-vaporizable rare refractory metals materially higher current densities may be employed.
  • current densities of from 8.5) to 9.! amperes per square decimeter of surface area have men employed without deleterious sputtering effects.
  • the specific maximum current density that may be applied will in part depend upon the electrode composition, and in part upon the depth and diameter of the recessed portion and upon the particular gas and gas pressure within the device.
  • hollow thorium electrode in the specific embodiment of the present invention, similar beneficial results may be obtained from employing hollow electrodes of the other thermionically active rare refractory metals uranium, zirconium, titanium, etc.
  • hollow refractory electrodes comprised for example or highly relractory metals such as tungsten, and tantalum, the recessed surface oi which may be coated superficially with a thermionically active material such as thorium, uranium, and the like.
  • Such refractory metal electrodes may also have the more reactive thermionically active metals incorporated therewith as an alloyed constituent or they may be also interiorly coated with other low temperature thermionically active material.
  • the exterior of the electrode may be coated with an electrically insulating material such as thorium oxide, aluminium oxide, magnesium oxide and the like, in accordance with the electrode structure set forth in Fig. 3 herein.
  • an electrode comprised of coherent thorium one face oi the electrode being recessed at least in part a substantial depth and the remaining faces being surfaced with refractory insulating material.
  • a gas discharge device comprising an enclosing glass envelope, an inert gas filling and at least one interior electrode, said electrode being comprised of an open ended hollow body of thorium.
  • a gas discharge device comprising an enclosing glass envelope, an inert gas filling and at least one interior hollow open ended electrode, said electrode being comprised at least interiorly of thorium and exteriorly surfaced with electrically insulating material.
  • a gas discharge device of the positive column type comprising an enclosing glass envelope, an inert gas filling and two open ended hollow spaced electrodes, said electrodes being comprised at least in part of thorium.
  • a gas discharge device the method of obtaining thermionic electron emission from relatively cold electrodes which comprises concentrating the positive ion bombardment during operation of said device upon a relatively small surface area of said electrode to efiect incandescence thereof to the temperature of active thermionic electron emission.
  • An open-ended hollow metal electrode comprised of a thermionically active metal body of the thorium group having one face thereof recessed a substantial depth.
  • An electrode comprised at least in part of a thermionically active metal body of the thorium group having one face thereof recessed a substantial depth and the remaining faces surfaced with a refractory insulating material.
  • a gas discharge device comprising an enclosing glass envelope, aninert gas filling and at least one interior hollow open-ended electrode. said electrode being comprised at least in part of a thermionically active metal of the thorium group.
  • a gas discharge device comprising an enclosing glass envelope, an inert gas filling and at least one interior hollow open-ended electrode, said electrode being comprised at least in part of a thermionically active metal of the thorium group and exteriorly surfaced with electrically insulative material.
  • a gas discharge .device of the positive column type comprising an enclosing glass envelope, an inert gas filling and two open-ended hollow spaced electrodes, said electrodes being comprised at least in part of a thermionically active metal body of the thorium group.
  • a gas discharge device of the positive column type comprising an enclosing glass envelope, an inert gas filling and two open-ended hollow spaced electrodes comprised substantially of a thermionically active metal of the thorium group, said device operating at relatively high electrode current densities with relatively low electrode potentials.
  • a gas discharge device comprising an enclosing glass envelope, an inert gas filling and at least onehollow open-ended electrode, said electrode having at least a part of its interior surface of a thermionically active material of the thorium group and exteriorly surfaced with electrically insulating material.
  • An electrode for a gas discharge device comprised of a tubular metallic body closed at one end and having at least a part of the interior surface coated with a thermionically active material.
  • An electrode for a gas discharge device comprised of a tubular metallic body closed at one end, a layer of a thermionically active material covering at least a portion of the interior surface and an electrically insulative material on the exterior surface of said body.
  • a cathode for a gas discharge device comprised of thorium, one face of said thorium cathodebeing recessed an appreciable depth and the remaining faces being surfaced with glow discharge suppressing sheathing material.
  • a cathode for a gas discharge device comprising an open ended hollow thorium metal body exteriorly sheathed with dielectric insulating material.
  • a cathode for a gas discharge device comprising an open ended hollow thorium metal body exteriorly sheathed with material of relatively higher electrode drop in potential.

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  • Discharge Lamp (AREA)
US417091A 1929-12-28 1929-12-28 Electrode positive column lamp Expired - Lifetime US1932025A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US417091A US1932025A (en) 1929-12-28 1929-12-28 Electrode positive column lamp
FR708351D FR708351A (fr) 1929-12-28 1930-12-24 Perfectionnements aux appareils à décharge dans un gaz
GB38992/30A GB376220A (en) 1929-12-28 1930-12-29 Improvements in or relating to gaseous discharge devices

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US417091A US1932025A (en) 1929-12-28 1929-12-28 Electrode positive column lamp

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US1932025A true US1932025A (en) 1933-10-24

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FR (1) FR708351A (fr)
GB (1) GB376220A (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2449113A (en) * 1944-07-22 1948-09-14 Fruth Hal Frederick Electric discharge device
US2716713A (en) * 1950-03-22 1955-08-30 Gen Electric Cold electrode pulse lamp structure
US2727169A (en) * 1950-03-22 1955-12-13 Gen Electric Thermionic electrode pulse lamp structure
US3205388A (en) * 1960-12-30 1965-09-07 Lany Beatrice Pearson De Drill hole type cathode with cooling means
US3614642A (en) * 1966-09-14 1971-10-19 Univ Maryland Gas laser
WO1988000758A1 (fr) * 1986-07-11 1988-01-28 Fox Leslie Z Lampe fluorescente a haute frequence
US5043627A (en) * 1988-03-01 1991-08-27 Fox Leslie Z High-frequency fluorescent lamp
EP0467713A3 (en) * 1990-07-19 1992-11-19 Tokyo Densoku Kabushiki Kaisha Discharge tube

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2449113A (en) * 1944-07-22 1948-09-14 Fruth Hal Frederick Electric discharge device
US2716713A (en) * 1950-03-22 1955-08-30 Gen Electric Cold electrode pulse lamp structure
US2727169A (en) * 1950-03-22 1955-12-13 Gen Electric Thermionic electrode pulse lamp structure
US3205388A (en) * 1960-12-30 1965-09-07 Lany Beatrice Pearson De Drill hole type cathode with cooling means
US3614642A (en) * 1966-09-14 1971-10-19 Univ Maryland Gas laser
WO1988000758A1 (fr) * 1986-07-11 1988-01-28 Fox Leslie Z Lampe fluorescente a haute frequence
US5043627A (en) * 1988-03-01 1991-08-27 Fox Leslie Z High-frequency fluorescent lamp
EP0467713A3 (en) * 1990-07-19 1992-11-19 Tokyo Densoku Kabushiki Kaisha Discharge tube

Also Published As

Publication number Publication date
GB376220A (en) 1932-07-07
FR708351A (fr) 1931-07-23

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