US2340631A - Secondary electron amplifier - Google Patents

Secondary electron amplifier Download PDF

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Publication number
US2340631A
US2340631A US407735A US40773541A US2340631A US 2340631 A US2340631 A US 2340631A US 407735 A US407735 A US 407735A US 40773541 A US40773541 A US 40773541A US 2340631 A US2340631 A US 2340631A
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Prior art keywords
anode
cathode
emitter
electron
electrode
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Expired - Lifetime
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US407735A
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English (en)
Inventor
Adrianus J W M Van Overbeek
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Individual
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Individual
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/02—Tubes in which one or a few electrodes are secondary-electron emitting electrodes

Definitions

  • This invention relates to an electron discharge tube comprising a secondary emission electrode having a surface which has the property of emitting secondary electrons when struck by a stream of primary electrons.
  • the principal object of this invention is to provide a simple and sturdy secondary electron emission tube which has low interelectrode capacitance and in which .the internal resistance does not change materially, even when the tube is used for short Waves.
  • an electron discharge tube comprises an electrode system including a cathode or similar source of primary electrons, at least one secondary emission electrode, and an anode, preferably a rod or strip, so placed that as viewed from the oathode it is behind a shield member, preferably a rod parallel to and in front of the edge of the anode.
  • the shield member is maintained at a constant, preferably cathode, potential.
  • the primary electron stream may be controlled by a control grid near the cathode.
  • the secondary emission electrode is concave or recessed, facing the cathode and surrounding the greater part of the anode, so that the secondary electrons go directly to the flat sides of the anode.
  • the concave secondary emission electrode surrounds the anode, save on the side facing the cathode, and the primary electrons are formed into a beam by beam forming means, such as a number of rod-shaped members, preferably near the anode shield rod.
  • beam forming means such as a number of rod-shaped members, preferably near the anode shield rod.
  • the drawing shows an electron discharge tube having a source of primary electrons, such as an indirectly heated oxide coated thermionic cathode i, near which is a conventional control grid 7 2.
  • a conventional screen grid 3 may be used, and
  • an output electrode or anode 4 preferably a flat strip or slat set edgewise to the cathode.
  • a secondary emission electrode or emitter 5 preferably concave or recessed, which partly surrounds the anode 5 and is open to the cathode I.
  • a shielding member such as a rod 6 which is interposed between the cathode and the edge of the slat anode and protects the anode from the primary electron stream indicated by heavy arrows.
  • the rod 6 is maintained at constant potential, such as cathode potential, either by a direct connection to the cathode inside the tube or by an external connection.
  • the inner or emitting surfaces of the concave emitter are the walls of a recess in which is the slat anode with its fiat sides directly exposed to the emitting surfaces, substantially none of the secondary electrons from the emitter return to the vicinity of the control and screen grids.
  • the beam forming rods i may be parallel to and beside the shield rod 6, which splits the beam into two parts, each of which impinges on an emitting surface of the emitter 5.
  • Figures 2 and 3 show in more detail a tube made in accordance with the invention and comprising a highly evacuated bulb l0 enclosing the electrode assembly, which in general is of conventional construction, with the electrodes held between a pair of mica spacers secured to support rods. It is desirable, as shown in these figures, to provide by sheet metal shields good electrostatic shielding between the electrode leads and for the upper ends of the grid rods.
  • the shields may conveniently be attached to electrodes 6 and 1, which may operate at ground potential.
  • the emitters may to advantage be approximately V-shaped in cross-section, and blackened on the outer surface, for example, by carbonizing, to facilitate heat radiation and thereby keep the emitters comparatively cool during operation.
  • the inner surface of the emitters 5 may be made to have high secondary electron emissivity by well known expedients, such as oxidizing the surface and then caesiating it, or by coating the surface with a very thin film of alkaline earth oxide.
  • the emitter 5 may be made of copper, with the emitting surfaces oxidized and subjected to an atmosphere of caesium vapor. Such an emitter has good stability and is only slightly affected by material thrown off from the oxide coated cathode I during operation of the tube.
  • the accompanying drawing shows schematically only part of the electrode system, but obviously several parts, each comprising a secondary emission electrode and an anode, can be provided for a common cathode and on one electrode assembly.
  • An electron discharge device comprising a cathode, an emitter including two divergent surfaces of high secondary electron emission constituting the walls of a recess open to said cathode, a slat anode edgewise to said cathode and in said recess, with the flat sides of said slat anode directly exposed to said surfaces, a rectilinear shielding member aligned with and between said cathode and said anode, and a grid electrode between said shield member and said cathode.
  • An electron discharge device comprising a planar cathode, an elongated concave secondary electron emitter facing said cathode, a rectilinear anode parallel to and within the confines of said emitter, and three parallel spaced rods between said anode and said cathode, the middle rod being in alignment with said anode and said cathode.
  • An electron discharge device comprising a planar cathode, an emitter including two divergent surfaces of high secondary electron emission constituting the walls of a recess open to said cathode, a slat anode edgewise to said cathode and in said recess, with the flat sides of said slat anode directly exposed to said surfaces, electrode means for forming the electron discharge from said cathode to said emitter into a beam which passes said anode, and a control grid near said cathode.
  • An electron discharge device comprising a planar thermionic cathode, a planar anode, a grid electrode between said cathode and said anode, a curved secondary electron emitter partly surrounding said anode and having toward said cathode an opening wider than said anode, a straight shielding rod parallel with said cathode and anode and in front of and parallel to said anode, and a conductor connecting said rod and said cathode together.
  • An electron discharge device as defined in claim 4 having a pair of rods parallel to and on opposite sides of the shielding rod and directly connected to it.
  • An electron discharge device comprising a planar cathode, an elongated concave secondary electron emitter open to said cathode with its longitudinal axis parallel to said cathode, a slat anode inside said emitter with its edge parallel to and facing said cathode, three spaced rods parallel to said cathode with the middle rod aligned with said cathode and anode, a conductor connecting said rods and said cathode together, and a grid electrode between said cathode and said rods.
  • An electron discharge device comprising, a cathode having a plurality of surfaces each of which emits a stream of primary electrons, shield means positioned along the path of each stream of primary electrons to direct the stream in two predetermined beams, secondary electron emitter means positioned in the paths of the primary electron beams and an anode positioned between the paths of the secondary electrons, the secondary electron emitting surface of said emitter means facing said anode to direct the secondary electrons to substantially the entire surface of the anode.
US407735A 1939-06-06 1941-08-21 Secondary electron amplifier Expired - Lifetime US2340631A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL217330X 1939-06-06

Publications (1)

Publication Number Publication Date
US2340631A true US2340631A (en) 1944-02-01

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ID=19779131

Family Applications (1)

Application Number Title Priority Date Filing Date
US407735A Expired - Lifetime US2340631A (en) 1939-06-06 1941-08-21 Secondary electron amplifier

Country Status (7)

Country Link
US (1) US2340631A (de)
BE (1) BE440174A (de)
CH (1) CH217330A (de)
DE (1) DE1074764B (de)
FR (1) FR868395A (de)
GB (2) GB544225A (de)
NL (1) NL52549C (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2530743A (en) * 1942-04-17 1950-11-21 Hartford Nat Bank & Trust Co Secondary emissive electric discharge tube
US2585057A (en) * 1939-07-28 1952-02-12 Int Standard Electric Corp Electron discharge apparatus
US2674661A (en) * 1948-08-12 1954-04-06 Rca Corp Electron multiplier device
US2675431A (en) * 1949-08-18 1954-04-13 Nat Union Radio Corp Transit time compensated multiplier tube
US2909702A (en) * 1948-10-01 1959-10-20 Siemens Ag Discharge vessel cooled by radiation

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2585057A (en) * 1939-07-28 1952-02-12 Int Standard Electric Corp Electron discharge apparatus
US2530743A (en) * 1942-04-17 1950-11-21 Hartford Nat Bank & Trust Co Secondary emissive electric discharge tube
US2674661A (en) * 1948-08-12 1954-04-06 Rca Corp Electron multiplier device
US2909702A (en) * 1948-10-01 1959-10-20 Siemens Ag Discharge vessel cooled by radiation
US2675431A (en) * 1949-08-18 1954-04-13 Nat Union Radio Corp Transit time compensated multiplier tube

Also Published As

Publication number Publication date
GB544225A (en) 1942-04-02
FR868395A (fr) 1941-12-29
DE1074764B (de) 1960-02-04
BE440174A (de)
GB629881A (en) 1949-09-29
NL52549C (de)
CH217330A (de) 1941-10-15

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