US2891188A - Gaseous discharge device - Google Patents

Gaseous discharge device Download PDF

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Publication number
US2891188A
US2891188A US496431A US49643155A US2891188A US 2891188 A US2891188 A US 2891188A US 496431 A US496431 A US 496431A US 49643155 A US49643155 A US 49643155A US 2891188 A US2891188 A US 2891188A
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United States
Prior art keywords
cathode
breakdown voltage
anode
gap
devices
Prior art date
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Expired - Lifetime
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US496431A
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English (en)
Inventor
Vivian L Holdaway
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AT&T Corp
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Bell Telephone Laboratories Inc
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Publication date
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US496431A priority Critical patent/US2891188A/en
Priority to CH340910D priority patent/CH340910A/de
Priority to BE545789A priority patent/BE545789A/fr
Priority to DEW18619A priority patent/DE1038657B/de
Application granted granted Critical
Publication of US2891188A publication Critical patent/US2891188A/en
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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
    • H01J17/02—Details
    • H01J17/30—Igniting arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/38—Cold-cathode tubes
    • H01J17/40—Cold-cathode tubes with one cathode and one anode, e.g. glow tubes, tuning-indicator glow tubes, voltage-stabiliser tubes, voltage-indicator tubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0064—Tubes with cold main electrodes (including cold cathodes)
    • H01J2893/0065—Electrode systems
    • H01J2893/0067—Electrode assembly without control electrodes, e.g. including a screen

Definitions

  • This invention relates to gaseous discharge devices, and more particularly to such devices especially suitable for usein switching networks.
  • the pd curve has a small slope so that slight variations in the gas density in the anode-'to-cathode' gap will not afiect the value of breakdown voltage. Thus stability of breakdown voltage can be readily attained within satisfactory limits.
  • this is the minimum breakdown voltage that can be applied to the device and accordingly the breakdown voltage stability has been attained by sacrificing another desirablecharacteristic for operation in gaseous discharge device switching networks,- namely, a high breakdown voltage. Accordingly, it has been proposed also to operate the device with a larger pd, and specifically with a larger main gap spacing, in order to increase the breakdown voltage.
  • a larger pd and specifically with a larger main gap spacing, in order to increase the breakdown voltage.
  • slight variations in spacing between devices or in the density in a given device due to a prior discharge in the device, give rise to large variations in the breakdown potential requisite 'to fire the tube, as the slope of the curve is large at these other points.
  • the anode-to-cathode spacing may also be initially determined during the manufacture of the device in other ways, known inthe art, such as by mechanical jigging and optical measurements.
  • the anode- 2,891,188 Patented June 16, 1959 pressure are chosen to attain a stable negative resistance characteristic at the current and frequency ranges at which it is intended to employ the device in a particular switching network, as further disclosed in Patent 2,804,565, of M. A. Townsend, issued August 27, 1957.
  • a device may be utilized in a subsequent connection or path through the network immediately upon extinction of a prior discharge in the device'and before the gas has had an opportunity to cool and the breakdown voltage of the tube return to its original and higher value.
  • a gaseous discharge device comprises a hollow cathode and an anode positioned opposite thereto and defining a gap therewith, the cathode, gap, and pressure being advantageously such that the device has a stable and usable negative resistance characteristic, as disclosed in the above-mentioned Townsend patent.
  • the cathode is mounted on a bimetallic support which is constructed so that on heating of the cathode, by the discharge, the variations in the gas density in the cathode-to-anode gap will @be compensated for by motion of the cathode away from the anode, thereby increasing the size of the gap. In this manner the breakdown voltage is maintained constant as the product pd remains constant.
  • the thermally responsive element supporting the cathode can readily be constructed to have a thermal characteristic so that it will provide precisely thisamount of motion of the cathode away from the anode for this decrease in gas density at thecathode or may, if desired, be designed to overcompensate slightly.
  • the cathode of a gaseous discharge device be supported by a thermally responsive element so constructed that motion of the cathode directly compensates for variation in the gas density adjacent the cathode to prevent decrease in the breakdown voltage of the device due to decrease in the gas density adjacent the cathode.
  • the breakdown voltage of a gaseous discharge device operated at other than thepd minimum of the Paschen curve be maintained constant with change of density in the anode, to-cathode gap due to heating of the cathode by the dish r ym n ns 1 c d Q 1 b me l ic s pv having a thermal characteristic such that the motion of I the cathode with relation to the anode exactly compen-v sates for the change in density in the anode-to-cathode gap.
  • Fig. 1 is a Paschen curve of breakdown voltage as a function of the pressure-distance product for an exemplary discharge device
  • Fig. 2 is a perspective view of one illustrative embodiment of this invention, a portion of the envelope being broken away to show the internal elements more clearly.
  • Fig. l is a typical plot of voltage breakdown V as a function of the pressure-distance product, pd.
  • the solid portion of the curve can be determined experimentally quite readily by maintaining the gas pressure constant and varying the spacing between the cathode and the anode. At some pressure and spacing corresponding to point on Fig. 1., breakdown occurs when the applied voltage is high enough so that each electron crossing the gap produces sufficient ionizations and'excitation in the gap to release another electron at the Cathode.
  • the number of collisions an electron can make in passing from the cathode to the anode become low enough to outweigh the aiding effect of the higher field strength at the cathode, resulting in an increase in the breakdown voltage
  • This portion of the curve is difiicult to find experimentally as the electrons will prefer to traverse a longer path from the cathode to the back of the anode or to the anode support wire, so that the actual distance d that is involved is, not definite. ,It can be measured however by using geometries which restrict these longer paths. With usual geometries, the actual breakdown voltage at these low values of pd is indicated by the dotted portion 13 of the curve and does not rise as greatly as theory indicates (due to these longer paths around the anode).
  • the breakdown voltage is also dependent on the particular gas and the cathode material, as well as on the pressure-distance product. In the particular devices for which this curve was plotted, as described more fully below, a molybdenum cathode was employed and the device was filled with neon.
  • Fig. 1 It canreadily be seen from Fig. 1 that one method of obtaining fairly constant breakdown voltage is to operate the device at the pd minimum point 11, as decrease. in density, due to heating of the cathode, will cause'the breakdown voltage to follow the dotted portion 13 of the curve.
  • this approach to the problem of maintaining the breakdown voltage constant requires that the breakdown voltage be a minimum and this may be very undesirable. It is therefore greatly to be preferred that the device be operated at some point to the right of the pd minimum, such as the point 15, with a breakdown voltage considerably higher than that at the Paschen minimum; in the embodiments for which this plot is descriptive the breakdown voltage at the Paschen minimum is volts and the breakdown voltage desired atpoint 15 is 220 volts or an increase of 30 volts.
  • a decrease in the gas density adjacent the cathode will in eflect cause the pa? product to decrease so that the breakdown voltage may be at a lower point on curve 10, such as point 16.
  • the breakdown voltage is only 200 volts, a drop of 20 volts from the breakdown voltage of the tube when cold.
  • a gaseous discharge device is provided which maintains the pressure-distance product constant so that the breakdown point of the device is always at the design point 15 regardless of the, prior operate or non-operate condition of the device.
  • FIG. 2 One specific illustrative embodiment of this invention is depicted in'Fig. 2 and comprises a wire anode 20 supported within a glass envelope 21 by a support lead 22.
  • the anode is positioned with its tip or end pointing towards a hollow cathode 24, which may be a helically coiled cathode as depicted, though other types of hollow cathodes may advantageously be employed.
  • the dimen: sions of cathode 24, the spacing between the cathode and the anode, and the gas pressure may advantageously be such that .theldevi'ce has a stable negative resistance characteristic over a usable current and frequency range, as further taught in Patent 2,804,565, of M. A.';Townsend, issued August 27, 1957.
  • the various types of cathodes disclosed in this Townsend patent may also all be employed, but this invention is not to be considered as limited to these or any particular cathode conf guration.
  • the baseof 'thecathode is secured, as by welding, near one end vof a bimetallicstrip comprised ,of plates 26 and 27. If desired, one end of the cathode coil may depend from the cathode and be secured to the bimetallic strip. Heat conduction from the cathode to the bimetallic strip is improved however by assuring a good thermal path therebetween.
  • the bimetallic strip is secured near its other end, as by welding, to a cathode support lead 28.
  • the cathode 24 and support lead 28 may be secured to the same or opposite sides of the bimetallic strip.
  • the two plates 26 and 27 which comprise the bimetallic strip or element are so arranged that heating of the plates, due to heating of the cathode 24, will cause the plates to bend, moving the cathode 24 farther away from the anode 20.
  • the plate 26 was a .010 x .050 x .187 inch molybdenum plate and plate 27 was a nickel plate with the same dimensions.
  • the operation of the bimetallic support to compensate for the change in density can readily be seen from consideration of a specific illustrative example.
  • the anode 20 was a .005 inch molybdenum wire mounted with its tip initially, i.e., in the cold condition, .012 inch from the hollow cathode 24, which was of molybdenum.
  • the envelope was filled with neon at 100 millimeters of pressure. In the cold state the temperature of both the cathode 24 and the envelope 21 was 25 C.
  • the device immediately after operation at a discharge current of .010 ampere would have the following characteristics.
  • the cathode temperature would be 250 C. and the average envelope temperature 75 C. causing the gas density at the cathode to decrease.
  • the pd product under these conditions corresponds to the point 16 on curve and a breakdown voltage of 200 volts.
  • the cathode is arranged to move away from the anode to increase the gap distance d an amount just suflicient to keep the pd product constant.
  • the bimetallic support provided a 6 mil movement when the tube had been operated at 0.010 ampere.
  • thermal compensating support using particular metals
  • various other types of such supports may be utilized.
  • the amount of motion required exactly to compensate for the change in density in the anode-to-cathode gap will of course depend on the specific device, the operating current, the original gas pressure, and the increase in temperature of the cathode due to the discharge.
  • the bimetallic element has been arranged exactly to compensate for the change in density so that the breakdown voltage is maintained constant.
  • it may be desirable, however, slightly to overcompensate thus giving an initial preference in the network to employing devices not immediately priorly employed in a connection through the network.
  • arranging the various devices so as to be slightly overcompensated will enable the design to be less critical.
  • the compensation aiforded by the thermal mounting of the cathode be somewhat less than required for exact compensation.
  • the anode may be also supported by a thermally responsive element, identical with that supporting the cathode, so that the anode moves to follow the oath ode and prevent ambient temperature changes aifecting the desired breakdown voltage characteristic.
  • a glow discharge device comprising an envelope, a gaseous filling in said envelope at a predetermined pressure, a hollow cathode within said envelope, a wire anode positioned with its end opposite to and directed towards the hollow portion of said hollow cathode and defining therewith a gap having an initial predetermined spacing, whereby said discharge device has initially a predetermined breakdown voltage, and means for maintaining said breakdown voltage constant with change in density of said gaseous filling in said gap due to .heating of said cathode by a discharge, said means comprising a bimetallic support for said cathode having a thermal characteristic such that the increase of spacing of said gap from said initial predetermined spacing exactly compensates for the decrease in density of said gaseous filling in said gap from said predetermined filling.
  • a glow discharge device for operation in a region where the breakdown voltage changes with density comprising an envelope, a gaseous filling within said envelope, an anode, a hollow cathode opposite said anode and de fining a gap therewith, said gap having a predetermined breakdown voltage, and means for preventing substantial decrease in said breakdown voltage on change in the gas density in said gap due to heating of said cathode by the glow discharge, said means comprising a bimetallic element supporting said cathode for motion towards and away from said anode and having a thermal characteristic such that said cathode moves away from said anode on heating of said cathode an amount compensating for the change in gas density in said gap on heating of said cathode.
  • a glow discharge device for operation at other than the pressure distance minimum of the Paschen curve comprising an envelope, a gaseous filling within said envelope, an anode, a cathode capable of maintaining a large glow discharge opposite said anode and defining a gap therewith, said gap having a predetermined breakdown voltage, and means for preventing said breakdown voltage decreasing on change in the gas density in said gap due to heating of said cathode by said glow discharge, said means comprising a bimetallic support for said cathode having a thermal characteristic such that the increase in the gap spacing on heating of said cathode is at least sufficient to prevent a decrease in the breakdown voltage of said gap.

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  • Gas-Filled Discharge Tubes (AREA)
  • Discharge Lamp (AREA)
  • Lasers (AREA)
US496431A 1955-03-24 1955-03-24 Gaseous discharge device Expired - Lifetime US2891188A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US496431A US2891188A (en) 1955-03-24 1955-03-24 Gaseous discharge device
CH340910D CH340910A (de) 1955-03-24 1956-01-24 Gasentladungseinrichtung
BE545789A BE545789A (fr) 1955-03-24 1956-03-05 Dispositif a decharge gazeuse.
DEW18619A DE1038657B (de) 1955-03-24 1956-03-09 Glimmentladungsroehre

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US496431A US2891188A (en) 1955-03-24 1955-03-24 Gaseous discharge device

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US2891188A true US2891188A (en) 1959-06-16

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US (1) US2891188A (de)
BE (1) BE545789A (de)
CH (1) CH340910A (de)
DE (1) DE1038657B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1203396B (de) * 1963-08-30 1965-10-21 Danfoss As UV-empfindliche Gasentladungsroehre nach dem Geiger-Mueller-Prinzip
US4329621A (en) * 1980-12-15 1982-05-11 Gte Products Corporation Starter and discharge lamp starting circuit

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1031796A (en) * 1910-10-08 1912-07-09 Westinghouse Electric & Mfg Co Lightning-arrester.
US1537680A (en) * 1923-12-21 1925-05-12 Gen Electric Incandescent-arc device
US1617065A (en) * 1923-03-17 1927-02-08 Westinghouse Lamp Co Intermittent glow lamp
US1640450A (en) * 1923-05-05 1927-08-30 Gen Electric Arc light
US2380496A (en) * 1943-11-29 1945-07-31 Rca Corp Electron discharge device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL72100C (de) * 1941-07-01
AT174660B (de) * 1951-12-17 1953-04-25 Adolf Ing Oberhuber Entladungsröhre

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1031796A (en) * 1910-10-08 1912-07-09 Westinghouse Electric & Mfg Co Lightning-arrester.
US1617065A (en) * 1923-03-17 1927-02-08 Westinghouse Lamp Co Intermittent glow lamp
US1640450A (en) * 1923-05-05 1927-08-30 Gen Electric Arc light
US1537680A (en) * 1923-12-21 1925-05-12 Gen Electric Incandescent-arc device
US2380496A (en) * 1943-11-29 1945-07-31 Rca Corp Electron discharge device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1203396B (de) * 1963-08-30 1965-10-21 Danfoss As UV-empfindliche Gasentladungsroehre nach dem Geiger-Mueller-Prinzip
US4329621A (en) * 1980-12-15 1982-05-11 Gte Products Corporation Starter and discharge lamp starting circuit

Also Published As

Publication number Publication date
CH340910A (de) 1959-09-15
BE545789A (fr) 1959-10-09
DE1038657B (de) 1958-09-11

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