US1946076A - Electron discharge tube - Google Patents

Electron discharge tube Download PDF

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Publication number
US1946076A
US1946076A US611272A US61127232A US1946076A US 1946076 A US1946076 A US 1946076A US 611272 A US611272 A US 611272A US 61127232 A US61127232 A US 61127232A US 1946076 A US1946076 A US 1946076A
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US
United States
Prior art keywords
cathode
heater
discharge tube
support
electron discharge
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Expired - Lifetime
Application number
US611272A
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English (en)
Inventor
Jonker Johan Lodewyk Hendrik
Karel Marinus Van Gessel
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RCA Corp
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RCA Corp
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Publication date
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/22—Heaters

Definitions

  • the invention relates to electron discharge tubes and more particularly to tubes comprising an indirectly heated cathode.
  • a cathode commonly consists of a cylindrical metal body,
  • the cathode body proper within which is arranged the heater which may consist of a hairpin-shaped wire of refractory material such, for example, as tungsten.
  • the cathode body usually consists of a nickel cylinder which surrounds the heater at some distance, if desired with the interposition ofan insulating material, and the outer surface of which is covered with a strongly electron emitting layer, for example, with barium oxide. It is usual to mount a cathode thus constructed within the tube with the aid of supports secured to the upper end and to the lower end of the cathode body. Oneof these supports may simultaneously to the cathode.
  • the invention has for its object to remove this drawback by a plain construction of an electric discharge tube comprising an indirectly heated cathode.
  • An electron discharge tube comprises an indirectly heated cathode, he heater and the cathode body of which are so shaped that the amount of heat developed per unit of the cathode surface by that portion of the heater which is located in the neighborhood of a point at which the cathode is supported, is larger than the amount of heat developed per unit of the cathode surface by a portion of the heater which is not located in the neighborhood of a point of support of the cathode. It is possible to obtain in this manner a uniform or substantially uniform distribution of the temperature over the whole surface of the cathode, which results in a better emission than with the indirectly heated cathode hitherto used.
  • the cathode body it is advantageous to constitute the cathode body by a small tube and to give the tube portion located in the neighborhood of the points of support a smaller diameter than the other por tion.
  • This portion located in the neighborhood of a point of support may be given for this purpose, for example, the shape of a cone.
  • Very satisfactory results are obtained by giving a portion of the heater of the cathode which is located in the neighborhood of a point of support per unit of length of the cathode a greater length than a portion of'this heater which isnot 'located in the neighborhood of a pointof support; -Very good results may also be obtained by giving the heater and the points located in the neighborhood of a point of support of the cathode a higher resistance than the points of this heater which are not located in the neighborhood-of a point of support of the cathode. found that with these constructions a substantially uniform temperature of the cathode body can always be obtained.
  • the amount of heat produced by a determined portion of the heater per unit of the oathode surface is meant this: a portion limited by two parallel planes perpendicular to the longitudinal axis of the cathode must be assumed to be removed from the latter.
  • a determined portion of the heater When the heater is traversed by a current, a certain amount of heat will be developed in this portion of the heater.
  • the cathode portion under consideration has a certain emitting surface the size of which can be determined. When determining the quotient of the amount of heat produced and the size of this surface, one obtains an amount of heat which is produced by the heater portion under consideration per unit of the cathode surface.
  • this quotient depends on the intensity of the current flowing through the heater.
  • the quotient valid for a determined cathode portion of the cathode may directly be compared with the quotient found for another cathode portion because one may start in this case from the same current intensity in the whole heater.
  • Figure 1 represents one embodiment of a discharge tube according to the invention
  • Figure 2 represents the cathode utilized in this tube
  • FIGS 3 and 4 are and Figure 5 is another form according to the invention.
  • 1 denotes the bulb of a discharge tube with a reentrant stem 2 and a pinch or press 3.
  • the tube contains an anode 4, a grid 5 and a cathode 6.
  • the latter consists of a cathode body 7 which may be constituted, for example, by a nickel tube which is coated with a strongly electron emitting layer, for example with barium oxide and within which is located the heater which may consist, for example, of a hairpinshaped wire of refractory material.
  • FIG. 2 distinctly shows the shape the cathode body and the heater may have according to the invention.
  • '7 denotes again the cathode body and 8 the heater whereas at 9' and 10 is shown the shape which the cathode body and the heater may havein order to obtain a satisfactory functioning according to the invenion.
  • the oathode sleeve 7 is shown as having the same form as that-shown in Figure 2, but the internal heater element; 8 is of such construction, as above described, that those portions thereof such as 9' and 10' which are in the neighborhood of points of support of the cathode with supports 11 and 11! are of ,higher resistance per unit of length
  • the cathode body is secured at its lower end to than other heater portions that are not in the neighborhood of a cathode support.
  • the invention is applicable to dischargetubes comprising an oblique or horizontal electrode system or to discharge tubes comprising more than one electrode system or a plurality of electrodes fulfilling the same function.
  • An indirectly heated cathode for an electron discharge tube comprising an electron emitting element, a heater adjacent to and substantially coextensive with said emitting element, and a support connected to said emitting element, the resistance of that portion of the heater which is'adjacent the point of connection between support and electron emitting element being greater than any other equal portion of the heater.
  • An indirectly heated cathode for an electron discharge tube comprising an electron emitting element, a support connected thereto, and a filamentary heater of the hairpin type adjacent, to and substantially coextensive with said emitting element and of uniform resistivity except for that portion which is adjacent the point of connection between support and electron emitting element which has a higher resistivity than all other equal portions of the heater.

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  • Discharge Lamp (AREA)
US611272A 1931-05-01 1932-05-14 Electron discharge tube Expired - Lifetime US1946076A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE384136X 1931-05-01

Publications (1)

Publication Number Publication Date
US1946076A true US1946076A (en) 1934-02-06

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Application Number Title Priority Date Filing Date
US611272A Expired - Lifetime US1946076A (en) 1931-05-01 1932-05-14 Electron discharge tube

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US (1) US1946076A (en))
BE (1) BE387951A (en))
FR (1) FR735516A (en))
GB (1) GB384136A (en))

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE739182C (de) * 1935-01-12 1943-09-14 Philips Patentverwaltung Verfahren zur Herstellung einer indirekt beheizten Kathode fuer elektrische Entladungsroehren
DE904570C (de) * 1940-10-30 1954-02-18 Henry Kershaw Verfahren zur Herstellung einer mantelfoermigen Kathode fuer Elektronenroehren

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Publication number Publication date
GB384136A (en) 1932-12-01
FR735516A (fr) 1932-11-10
BE387951A (en))

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