US2595634A - Pressurized alkali-metal tube - Google Patents

Pressurized alkali-metal tube Download PDF

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Publication number
US2595634A
US2595634A US215579A US21557951A US2595634A US 2595634 A US2595634 A US 2595634A US 215579 A US215579 A US 215579A US 21557951 A US21557951 A US 21557951A US 2595634 A US2595634 A US 2595634A
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United States
Prior art keywords
cathode
metal
anode
vapor
fins
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Expired - Lifetime
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US215579A
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English (en)
Inventor
John L Boyer
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 Electric Corp
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Westinghouse Electric Corp
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Filing date
Publication date
Priority to BE509902D priority Critical patent/BE509902A/xx
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US215579A priority patent/US2595634A/en
Priority to FR1057082D priority patent/FR1057082A/fr
Application granted granted Critical
Publication of US2595634A publication Critical patent/US2595634A/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
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/20—Selection of substances for gas fillings; Specified operating pressures or temperatures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/28—Cooling arrangements

Definitions

  • My invention relates to vapor-electric devices or tubes, and particularly to a low-arcdrop hot-cathode arc-discharge device using a vaporizable discharge-metal selected from the alkali-metal group consisting of cesium, rubidium and potassium.
  • the present invention is an improvement over the vapor-electric devices which are described and claimed in an application of August P. Colaiaco and myself, Serial No. 144,354, filed February 15, 1950.
  • the breakdown-voltage of an evacuated or low-pressure gap-device is a function of the pd product, where p is the pressure and d the distance between electrodes. At extremely low values of this product, the breakdown-voltage is very high, up .into the thousands of volts, but as this product increases the breakdown-voltage rapidly falls until it reaches a minimum breakdown-voltage, after which any further increase in the pd product will cause the breakdown-Voltage to rise again, slowly at first, and later on more rapidly.
  • the minimum breakdown-voltage is of the order of some200 to 500 volts, depending upon the gaseous medium in the space separating the electrodes, and the pressure-distance value pd at which this minimum breakdown-voltage occurs is also variable, depending upon the gaseous material.
  • the pressure p, in the pd product will be the vapor-pressure of the metal at the coolest internal temperature of the tube, during the operation of the device, ,or the condensation-temperature of the dischargemetal.
  • the curve which plots the vapor-pressure of different metals, as a function of temperature is a characteristic curve ofthe metal, which differs according to the metal.
  • Mypresent invention in brief, involves, as its outstanding 'feature, the provision of a blastof alkali-metal vapor which acts as a diffusion pump 'or ejector 'for causing a greater vaporpressure in the space'in which the heated cath ode-surface-islocated, while using a lower vaporpressure in the region surrounding the anode, soas to make it' possible for the anode to hold a relatively high negative voltage, without breakdown, during the nonconducting periods of .theftube.
  • my invention consists-in the systems, combinations, structures, parts, and methods of design andoperation, hereinafter described, and illustrated in .the accompanying drawing, the single figure of which is a .somewhat diagrammatic simplified cross-sectional view of an exemplary-form of tube-structure embodying my present invention, with a diagrammatic representation of-an illustrative grid-control circuit which might be used.
  • my vapor-electric device has an evacuated container or enclosuremeans I including a metal anode-portion 2 at the top, and a metal cathode-portion 3 at the bottom.
  • the enclosure-means I will include an intermediate tubular side-wall portion 4 which carries a massive perforated metal barrier-grid 5 in good thermal and electrical contact therewith, said barrier-grid being disposed between the active portions of the anode and the cathode, respectively, as described and claimed in an applicationof .Robert J. Ballard :and myself, Serial No. 205,899, filed.January 13, 1951.
  • the enclosureemeans 1 includes insulating seals between the severalmetal parts, such as the anodeto;grid,seal 6 between the anode and grid portions 2 and 4, :and the grid-to-cathode seal 1 betweenthe grid and cathode portions 4 and '3.
  • the 'bottom'end-wall of the cathodeend ⁇ 3 of the-enclosure-means I is provided with a tubular re-entrant cathode-portion 8, which is provided with a hermetically closed inner end 9, which is spaced below the barrier or grid 5.
  • the tube contains a quantity of a vaporizable discharge-metal which is shown in the form of a pool or reservoir l l of an alkali-metal which is chosen from the group comprising cesium,
  • this pool or reservoir other heater-lead l may be connected to the closure-plate [3, which may be connected to the inner end of the heater 1? by means of a vertical rod I8.
  • the cathode As is common in the hot-cathode type of alkalimetal rectifier, the cathode is provided with a finned portion, for increasing the amount of active cathode-surface, which is concentrated in a relatively small space.
  • the cathode-fins are shown in the form of a large number of vertical radially extending cathode-fins 2B.
  • the cathode-fins 2:: must be in good thermal and electrical relation to the heated cathode-tube 8.
  • I in order to provide a chimney through which alkalimetal vapors can be supplied to the top end of the re-entrant cathode-tube 8, I preferably supply a second tubular hot-cathode member 2
  • the cathode-fins 2B are secured to the outer surface of the cathode-tube 2
  • the portion of the alkali-metal pool which surrounds the re-entrant cathode-tube 8 is heated to a vaporizing temperature by this tube, and in order to cause this vapor to rise upwardly in the space between the two cathode-tubes 8 and 2
  • a metal washer 24 secured to the bottom end of the cathode-tube 2
  • the heat from the re-entrant' cathode-tube 8 causes a high vapor-pressure which produces a blast of alkali-metal vapor which passes up to the top of the re-entrant tube 8, and at this point the direction of vapor-flow is changed, as by means of a dome-shaped metal cap 28, which is held spaced closely above the top edge of the cathode-tube 2!, as by means of one or more supporting-wires 29, so as .to provide a narrow annular space 36 through which the vapor-blast is directed downwardly at a high velocity, toward the cathode-fins 20, thus serving as a difiusionpump, or ejector for drawing the internal vapor, within the rectifier, down away from the upper region, in which the anode 2 and the grid 5 are located.
  • cooling-air or other coolingfluid
  • arrows 33 which are intended to illustrate any suitable means, either a natural chimney-draft, or blower-means (not shown), for causing an upward movement of cooling-air surrounding the rectifier.
  • this cooling-air is confined by a chimney-like enclosure 34 which surrounds the lower portion of the vertical cylindrical-wall portion 35 of the cathode-part 3 of the tube-enclosure, in closely spaced relation thereto, so as to cool the same.
  • the chimney 34 also extends upwardly beyond the top of the enclosure l, preferably being provided with an insulating tubular chimney section 35', to insulate the bottom chimney-portion 34 from the top chimney-portion 3B, which is shown in the form of a metal spinning.
  • the anode-portion 2 which is located at the top of the enclosure l, is preferably provided with a re-entrant metal anode-portion 42, having a closed bottom end 43 which constitutes the active anode-surface of the rectifier.
  • a massive upstanding copper pillar 44 Centrally secured to the active anode-plate 43 is a massive upstanding copper pillar 44 which has good thermal and electrical connection thereto, and an anodelead cable 44 is secured in the top of this copper pillar 44.
  • the copper pillar 44 carries a plurality of radially extending fins 45, which are in good thermal contact with the pillar 44, and which may also be in good thermal contact with the re-entrant anode-portion 42-43.
  • These fins 45 are illustrated as being provided with deep slots 46, extending down from their tops; and the metal spinning 36 of the air-directing chimney is provided with a bent-down portion 41 which enters down into these slots 46 and causes the cooling-air to circulate downwardly into the re-entrant anode-portion 42, and thence upwardly out of the device.
  • the cooling-air passes the lower cylindrical cathode-portion 35 first, it makes this portion the coolest point in the device, so that the alkali-metal vapor is condensed on the inner wall of this lower cylindrical cathode-member 35, from which point the condensed material returns to the cathode pool H.
  • the anode 42-43 is also cooled, but since the cooling-air is heated in passing over the cathode outer-wall surface 35, the anode 42-43 is not cooled to quite as low a temperature as the cathode wall-surface 35. It will be understood that any cooling-means, which serves the general purpose above outlined, will be satisfactory.
  • Any suitable grid-circuit means may be used.
  • a common form of grid-control is shown, whereby the grid 5 is connected to the cathode-lead 48 of the device, through a negative-bias means 49, an alternating-current grid-voltage source 50, and a grid-resistance R, so as to cause the grid 5 to permit the firing of the tube at a desired point in the positive voltage-Wave which is applied to the anode 42-43.
  • a strong blast of alkali-metal vapor is supplied from the alkalimetal pool or reservoir II to the diifuser-gap 3B, for producing a downwardly directed vapor-blast which causes a greater vapor-pressure in the space occupied by the cathode-fins 20 than in the space near the anode end of the device.
  • the upper halves of the cathode-fins 25 may be surrounded by a cylindrical heat-insulating shield 52, for preventing too much cooling of the vapor on the top part of the cathodefins 20.
  • the resulting high-pressure region around the cathodefins increases the maximum-current rating of the tube many times, for any given electronemitting cathode-surface area, thus enabling a given size of tube to carry much more current, or making it possible to make a tube of a given current-rating much smaller than heretofore.
  • the low vapor-pressure p in the region around the anode 43 and the grid 5 enables the tube to maintain a high breakdownvoltage for preventing backfiring during the nonconducting periods of the tube, when a high negative voltage is applied to the anode 42.
  • a vapor-electric device having an evacuated enclosure-means including a metal anode-portion of the enclosure-means at one end of the device, a metal cathode-portion oi the enclosure-means at the other end of the device, and an insulating sealing-means between said anode and cathode portions, said metal cathode-portion including i a metal tubular cathode-member and metal cathode-fins carried by said metal tubular cathodemember in good thermal and electrical relation thereto, said cathode-fins extending into the spac within the device to increase the effective cathode surface-area in the device, a quantity of a vaporizable discharge-metal within the device, said vaporizable discharge-metal being selected from the group comprising cesium, rubidium and potassium, means for heating said tubular cathode-member and said quantity of vaporizable discharge-metal, means for providing a vapor-duct from said quantity of vapor
  • a vapor-electric device having an evacuated enclosure-means including a metal anode-portion of the enclosure-means at the top of the device, a metal cathode-portion of the enclosuremeans at the bottom of the device, and an insulating sealing-means between said anode and cathode portions, said metal cathode-portion including a metal tubular cathode-member and metal cathode-fins carried by said metal tubular cathode-member in good thermal and electrical relation thereto, said cathode-fins extending into the space within the device to increase the efiective cathode surface-area in the device, a quantity of a vaporizable discharge-metal disposed at the bottom of the evacuated enclosure-means, said vaporizable discharge-metal being selected from the group comprising cesium, rubidium and potassium, means for heating said tubular cathode-member and said quantity of vaporizable discharge-metal, means for providing a vapor-
  • a vapor-electric device having an evacuated enclosure-means including a metal anode-portion of the enclosure-means at one end of the device, a metal cathode-portion of the enclosuremeans at the other end of the device, and an insulating sealing-means between said anode and cathode portions, the end-wall of said cathodeportion of the enclosure-means including a metal tubular re-entrant cathode-portion having a closed inner end which is spaced from the anodeportion of the device, cathode-fins disposed outside of said re-entrant cathode-portion in good thermal and electrical relation thereto, a quantity of a vaporizable discharge-metal within the device, said vaporizable discharge-metal being selected from the group comprising cesium, rubidium and potassium, means for heating said reentrant cathode-portion and said quantity of vaporizable discharge-metal, means for providing a vapor-duct from said quantity of vapor
  • a vapor-electric device having an evacuated enclosure-means including a metal anodeportion of the enclosure-means at the top of the device, a metal cathode-portion of the enclosuremeans at the bottom of the device, and an insulating sealing-means between said anode and cathode portions, the end-wall of said cathodeportion of the enclosure-means including a metal tubular re-entrant cathode-portion having a closed inner end which is spaced from the anodeportion of the device, means for heating the inside of said re-entrant cathode-portion, cathode-fins disposed in good thermal and electrical conducting-relation to said re-entrant cathode-portion, a quantity of a vaporizable discharge-metal disposed near the junction of said re-entrant portion with the end-wall of the cathode-portion of the enclosure-means whereby said dischargemetal is vaporized by the heat of said re-entrant portion, said discharge
  • a vapor-electric device having an evacuated enclosure-means including a metal anodeportion of the enclosure-means at the top of the device, a metal cathode-portion of the enclosuremeans at the bottom of the device, and an insu lating sealing-means between said anode and cathode portions, the end-wall of said cathodeportion of the enclosure-means including a metal tubular re-entrant cathode-portion having a closed inner end which is spaced from the anodeportion of the device, means for heating the inside of said re-entrant cathode-portion, a hot-cathode element having a tubular hot-cathode member surrounding said re-entrant cathode-portion in heat-exchanging relation thereto, the outside of said tubular hot-cathode member carrying cathode-fins in good thermal and electrical contact therewith, a quantity of a vaporizable dischargemetal disposed near the junction of said reentrant portion with the

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US215579A 1951-03-14 1951-03-14 Pressurized alkali-metal tube Expired - Lifetime US2595634A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE509902D BE509902A (en(2012)) 1951-03-14
US215579A US2595634A (en) 1951-03-14 1951-03-14 Pressurized alkali-metal tube
FR1057082D FR1057082A (fr) 1951-03-14 1952-03-14 Tubes à décharges électriques dans une vapeur, à métal alcalin

Applications Claiming Priority (1)

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US215579A US2595634A (en) 1951-03-14 1951-03-14 Pressurized alkali-metal tube

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US2595634A true US2595634A (en) 1952-05-06

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BE (1) BE509902A (en(2012))
FR (1) FR1057082A (en(2012))

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3460024A (en) * 1964-07-16 1969-08-05 Csf Gas-filled discharge tube and electrical energy generators using the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3460024A (en) * 1964-07-16 1969-08-05 Csf Gas-filled discharge tube and electrical energy generators using the same

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Publication number Publication date
BE509902A (en(2012))
FR1057082A (fr) 1954-03-04

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