US2516675A - Electrode structure for gas discharge devices - Google Patents

Electrode structure for gas discharge devices Download PDF

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Publication number
US2516675A
US2516675A US726608A US72660847A US2516675A US 2516675 A US2516675 A US 2516675A US 726608 A US726608 A US 726608A US 72660847 A US72660847 A US 72660847A US 2516675 A US2516675 A US 2516675A
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US
United States
Prior art keywords
grid
tube
shield
anode
control
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US726608A
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English (en)
Inventor
Gerald G Carne
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.)
RCA Corp
Original Assignee
RCA Corp
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Filing date
Publication date
Priority to BE480117D priority Critical patent/BE480117A/xx
Priority to FR957927D priority patent/FR957927A/fr
Application filed by RCA Corp filed Critical RCA Corp
Priority to US726608A priority patent/US2516675A/en
Priority to GB32176/47A priority patent/GB652742A/en
Application granted granted Critical
Publication of US2516675A publication Critical patent/US2516675A/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
    • H01J17/56—Thermionic-cathode tubes with one cathode and one anode having one or more control electrodes for preventing and then permitting ignition, but thereafter having no control

Definitions

  • One form of gas tube' employingagaseous atmosphere, preferably argon or Xenon, consists ofna thermionic cathode; an anode and a control particularly to electrode mountedzinalignment between the two.
  • Aimetal :shield encloses-the threeelectrodes and has a -portionforming-a screen grid between the anode and control electrode.
  • the controlgrid bias may be shift-ed in-apositive direction above this critical; voltage value by the application of a signal voltage so as to permit thetube to conduct In some applications oi these tubes it is desirable-to control-a power circuit by a small input
  • the use of a high grid resistance has presentedv some seriousproblems;
  • Anundesired flow of -cur rent :in thegridcircuit may be initiated by various conditionswithin the tube, the eiT'ects of which are-accumulative.
  • Thev gas. tube disclosed in iFig. 1 has 1 an envelope lfllclosed' atithe; bottom by. a glass ste portion, not shown. Projectingup from thest'r portion is :a glass press-i 2 upon-which are inount a. plurality of. electrodes: Aycathfodesleeve supported :from press; I2 is thermionically' heated; by a filament I 5.
  • the outer surface of the'cathod" sleeve ll this lcoveredsina wellknown manner wit an electron emissive c'oating
  • The'anode T6 is along narrowwplate mounted-axiallyparallel'to 1 the cathode-.-.sleeve T .l 4: Btween the cathode] 4f; andsthe.
  • anode l 6 is mounted a control grid l8 in Y theform ofan elongated metal ribbonloopj Asshown in- Figs- 1 and 'Z th e control grid i8 i 'formed with flat sides enclosi'nga longina rrowj aperture 1 I. This.
  • V lr H from the cathodejdto the anode
  • Thistle tron emission ionizesthegas ofjthetub e thereby establishing an-arc discharge vbetween the anode and cathode.
  • the ionization path and'consef rquently .thearc discharge are confined tyne metal. shie1ds
  • 9;.-.20 and 2 ltothe s'pace between t the anode; and cathode electrodes
  • This WeILd-I finedzarc discharge also passes essntially throiighl the-controlrgrid.aperture' H. T When a sufiiciently negative bias.
  • Fig. 3 discloses a relay circuit in which a relay 56 is energized by an increase in light falling upon a photoelectric tube 50.
  • electrical energy is derived from a source of alternating current applied to circuit terminals 32.
  • a positive voltage is supplied to the anode I6 of the gas control tube I during every other half cycle of line voltage when the circuit conductor 36 of the alternating current line is positive.
  • control grid I8 receives a negative bias through the resistance 44 which is connected to the negative conductor 38 of the circuit.
  • Contact46 on the resistance '44 is made adjustable so as to vary the negative value of this control grid bias.
  • Resistance 44 is part of a shunt 40 which includes a resistance 42 between the positive portion 36 and the negative portion 38 of the A. C. circuit.
  • resistance 42 may be around 20,000 ohms, while resistance 44 may be around 1,000 ohms.
  • the cathode l4 of the gas control tube ii) is connected to this shunt 40 at 43 a point between the resistance 42 and 44. With this arrangement, the IR, drop across resistance 42 determines the difference in potential between the cathode i4 and the anode H5.
  • the anode 52 of a phototube 50 is connected directly to the positive portion 36 of the A; C. circuit.
  • Aphotoelectron emitting cathode 54 of the phototube 58 is connected directly to the negatively biased grid circuit 45.
  • a large resistance 48- preferably of from oneto megohms is inserted into the control grid circuit 45.
  • a relay 56 is connected in series and is adapted to be operated whenever there is a current flow or arc discharge between the cathode I4 and the anode l6 of tube ill.
  • the filament for heating the cathode l4 of tube In derives its source of energy from the secondary of a transformer 58 whose primary is connected in the alternating current circuit.
  • This circuit arrangement of Fig. 3 utilizes the gas tube ID as a control for the operation of relay 56.
  • the conduction of tube i0 and thereby the energization of relay 56 is governed by an increase of light impinging upon the photoelectron emitting cathode 54 of the phototube 50.
  • Contact of the control grid circuit 45 may be adjusted so that as long as illumination upon the cathode 54 is less than a certain value the control grid I8 will remain sufl'iciently negative to prevent conduction of tube It.
  • the IR dropacross resistance 48 reduces the negative potential of the control grid i8 above the critical cut-off value and the tube 10 then conducts to operate relay 56.
  • control grid 18 In order to retain proper control of the gas tube In, in such applications as shown in Fig. 3, the negative bias of the control grid 18 should remain constant. This is possible as long as the negative charge on control electrode [8 is not diminished in any undesired manner. However, the
  • negative value of the charge on grid I8 may be reduced by neutralization due to the flow of positive gas ions to the control electrode and due to escape or leakage of electrons from the control electrode.
  • the presence of the high resistance 48 in the grid circuit 45 prevents the maintenance of the desired negative grid bias if the factors neutralizing the grid are sufliciently large. In this latter case there would result a shift of the grid potential toward the positive and a consequent loss of grid control.
  • This phenomenon of grid neutralization may be produced by a plurality of factors. Some of these factors are well recognized and have been eliminated or counteracted by various Ways. Ionization of the gas in control tube it, may occur between exposed leads within the tube or due to electronic emission between grid 18 and anode l6. Electron leakage from the control grid l8 may occur because of high difference of potential between this electrode and the anode I6. Electron emission from the grid l8 may also occur from its bombardment by positive gas ions and as its temperature increases during tube operation.
  • Emission from control grid [8 can be reduced by lowering the grid operating temperature or in increasing the work function of grid electrode 18.
  • control grid emission such as gold plating the control electrode l6; using for grid la a magnonickel wire which has a low electron emission; and the provision of heat radiating fins upon grid I8.
  • all of these expediencies helped to reduce the value of the positive grid shift only by approximately one-third. The situation was improved but in no way solved. I felt that it was quite possible that electron emission could be taking place from'the shield grid 25 or from some other portion of the shield 20. However, this was not obvious as several attempts which I made to measure a current flow to the shield failed.
  • My invention is a means to reduce shift in control voltage of the control grid by reducing shield emission through lowering the temperature of the shield 20 and of the space enclosed by this shield.
  • This means is a provision of a dull roughened surface 23 on the outside of the grid 20. This great increase in surface area due to the roughening 23 results in a large increase in heat radiation by the shield 20.
  • the best method of reducing the shift in the grid characteristic was by spraying the shield 20 with a coating of nickel oxide which when reduced by hydrogen firing presented a dull rough nickel surface 23.
  • the nickel oxide was mixed with a nitrocellulose binder.
  • This coating mixture can be applied to the shield 20 by several ways such as painting, spraying, or dragging.
  • the coated shield is air dried and then placed in a hydrogen furnace for approximately 10 minutes at 1000 C. During this hydrogen firing the nickel oxide is reduced to finely divided nickel particles. At this furnace temperature, the nitrocellulose binder is burned on" and the nickel particles sintered to the surface of the metal shield 20.
  • the time of firing and the furnace temperatures are not critical as the same reaction can take place at lower temperatures such as 700 over a longer period of time.
  • This method of providing a roughened nickel coating 23 to the shield electrode 20 has resulted in reducing the grid voltage shift from approximately volts to less than 0.5 volt, a point where the grid shift is not a problem.
  • This improvement of tube operation but undoubtedly the greatest contributing factor is reduction of the operating temperature within the interelectrode space enclosed by the tube shield 20. It is apparent that the increased surface of radiation of the shield, as well as its dull coloration, lowers the temperature of grid 26 and shield 20 to a point where a gas ionizing electron emission from the shield grid 26 or any part of the shield 20 to anode I 6 is at a minimum.
  • An electron discharge device comprising a sealed envelope, a gaseous medium within said envelope, an anode electrode mounted within said envelope, an electron emitting electrode spaced within said envelope from said anode electrode, a non-emitting control electrode mounted between said anode and said electron emitting electrodes, a tubular metal shield within said envelope enclosing all of said electrodes, said shield having an apertured portion extending between said anode and said control electrode, said shield having a rough coating of nickel metal particles sintered to the outer surface thereof to minimize electron emission between any portion of said shield and said anode electrode.
  • a gaseous discharge device comprising a sealed envelope, an anode mounted within said envelope, an electron emitting cathode spaced within said envelope from said anode, a shield electrode within said envelope adapted to be negatively biased relative to said anode and having a portion extending between said anode and cathode electrodes, a rough coating of nickel metal particles sintered to a portion of the surface of said shield electrode to minimize electron emission between said shield and said anode electrode.
  • a shield assembly adapted to be disposed at a negative bias within the sealed envelope of a gaseous electron discharge device, comprising a tubular metal body portion for enclosing the electrodes of said tube and a metal plate closing each end of said tubular body to confine the gaseous discharge of the tube in the space within said tubular body portion, a rough coating of nickel metal particles sintered to the outer surface of said cylindrical body portion to minimize electron emission from said shield.

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  • Physical Or Chemical Processes And Apparatus (AREA)
  • Microwave Tubes (AREA)
US726608A 1947-02-05 1947-02-05 Electrode structure for gas discharge devices Expired - Lifetime US2516675A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE480117D BE480117A (US07122603-20061017-C00294.png) 1947-02-05
FR957927D FR957927A (US07122603-20061017-C00294.png) 1947-02-05
US726608A US2516675A (en) 1947-02-05 1947-02-05 Electrode structure for gas discharge devices
GB32176/47A GB652742A (en) 1947-02-05 1947-12-05 Gaseous electron discharge device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US726608A US2516675A (en) 1947-02-05 1947-02-05 Electrode structure for gas discharge devices

Publications (1)

Publication Number Publication Date
US2516675A true US2516675A (en) 1950-07-25

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US726608A Expired - Lifetime US2516675A (en) 1947-02-05 1947-02-05 Electrode structure for gas discharge devices

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US (1) US2516675A (US07122603-20061017-C00294.png)
BE (1) BE480117A (US07122603-20061017-C00294.png)
FR (1) FR957927A (US07122603-20061017-C00294.png)
GB (1) GB652742A (US07122603-20061017-C00294.png)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2770751A (en) * 1953-02-27 1956-11-13 Rca Corp Construction of gas-filled tubes, particularly shielding
US2777966A (en) * 1954-03-08 1957-01-15 Rca Corp Gas discharge devices
US2797364A (en) * 1954-01-26 1957-06-25 Niles Breger Apparatus for dimming automobile head lights
US2813217A (en) * 1952-03-18 1957-11-12 Rca Corp Electrode arrangement for gas tubes
US2853652A (en) * 1953-10-12 1958-09-23 Gen Electric Light responsive system
US3084282A (en) * 1961-01-03 1963-04-02 Space Technology Lab Inc Trigger circuit

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1794315A (en) * 1924-10-09 1931-02-24 Gen Electric Electron-discharge apparatus
US2040883A (en) * 1935-05-29 1936-05-19 Solomon Guillermo Electronic tube
US2160086A (en) * 1936-12-05 1939-05-30 Bell Telephone Labor Inc Electron discharge device
US2203639A (en) * 1939-08-26 1940-06-04 Electrons Inc Vacuum tube construction
US2431237A (en) * 1945-10-19 1947-11-18 Westinghouse Electric Corp Control circuit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1794315A (en) * 1924-10-09 1931-02-24 Gen Electric Electron-discharge apparatus
US2040883A (en) * 1935-05-29 1936-05-19 Solomon Guillermo Electronic tube
US2160086A (en) * 1936-12-05 1939-05-30 Bell Telephone Labor Inc Electron discharge device
US2203639A (en) * 1939-08-26 1940-06-04 Electrons Inc Vacuum tube construction
US2431237A (en) * 1945-10-19 1947-11-18 Westinghouse Electric Corp Control circuit

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2813217A (en) * 1952-03-18 1957-11-12 Rca Corp Electrode arrangement for gas tubes
US2770751A (en) * 1953-02-27 1956-11-13 Rca Corp Construction of gas-filled tubes, particularly shielding
US2853652A (en) * 1953-10-12 1958-09-23 Gen Electric Light responsive system
US2797364A (en) * 1954-01-26 1957-06-25 Niles Breger Apparatus for dimming automobile head lights
US2777966A (en) * 1954-03-08 1957-01-15 Rca Corp Gas discharge devices
US3084282A (en) * 1961-01-03 1963-04-02 Space Technology Lab Inc Trigger circuit

Also Published As

Publication number Publication date
GB652742A (en) 1951-05-02
FR957927A (US07122603-20061017-C00294.png) 1950-02-28
BE480117A (US07122603-20061017-C00294.png)

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