US3167679A - Cathode structure - Google Patents

Cathode structure Download PDF

Info

Publication number
US3167679A
US3167679A US95677A US9567761A US3167679A US 3167679 A US3167679 A US 3167679A US 95677 A US95677 A US 95677A US 9567761 A US9567761 A US 9567761A US 3167679 A US3167679 A US 3167679A
Authority
US
United States
Prior art keywords
cathode
wires
slots
tubular member
wire
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
US95677A
Other languages
English (en)
Inventor
Laurence G Lyon
John W West
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.)
AT&T Corp
Original Assignee
Bell Telephone Laboratories Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to FR1317679D priority Critical patent/FR1317679A/fr
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US95677A priority patent/US3167679A/en
Priority to GB7962/62A priority patent/GB990690A/en
Priority to DEW31839A priority patent/DE1298645B/de
Application granted granted Critical
Publication of US3167679A publication Critical patent/US3167679A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/04—Cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/04—Cathodes
    • H01J23/05—Cathodes having a cylindrical emissive surface, e.g. cathodes for magnetrons
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J3/00—Details of electron-optical or ion-optical arrangements or of ion traps common to two or more basic types of discharge tubes or lamps
    • H01J3/02—Electron guns
    • H01J3/027—Construction of the gun or parts thereof

Definitions

  • This invention relates to electron discharge devices and, more particularly, to a cathode structure for use in electron discharge devices of, for example, the traveling wave tube type.
  • Traveling wave tubes in general, utilize the interaction between an electron beam and an electromagneti wave traveling in close proximity to the beam to produce amplification of the wave.
  • Such devices are well adapted for use in communications systems by virtue of the fact that they give high gain over an exceptionally broad band of frequencies in the microwave range. Because of these virtues, traveling wave tubes have proven to be quite useful tools in radio relay systems operating in the microwave range.
  • the cathode assembly comprises a hollow tubular member having at one end thereof an electron emitting cap. Within the tubular member is an insulated heating coil for heating the cap to emission temperature. Surrounding the tubular member and spaced therefrom is a hollow metallic shell within which is mounted a slotted support member which also surrounds the tubular member.
  • tubular member is supported by the support member by means of very fine wires which pass through the slots in the support member, through slots at the cap end of the tubular member, through slots in the support member, and through slots at the other end of the tubular member thereby forming a loop of wire.
  • Each wire thus wound is fixed at its ends to the support member.
  • the wires are wound under a high degree of tension, but suiticiently within the yield limit of the material of which the wires are made that thermal expansion and contraction of the wires and the tubular member do not perinanently deform the wires.
  • the angle that the wires rnalre with the axis of the tubular member is such that the wires are subjected substantially exclusively to tension and compression forces during operation, under which conditions the wires extending between the support member and the tubular member elfectively act as columns.
  • wires are or" a material having very low thermal conductivity, so that the principal heat losses are through radiation only.
  • FIG. 1 is a sectional view of the electron gun end of a traveling wave tube showing the location or" the cathode structure of the invention
  • FIG. 2 is a sectional view of the cathode structure of the invention.
  • FIG. 3 is an exploded perspective view of one portion of the cathode structure of the invention.
  • FIG. 4 is an exploded perspective view of another portion of the cathode structure of the invention.
  • FIG. 5 is a diagrammatic view of the cathode structure indicating its behavior under varying thermal conditions.
  • FIG. 1 there is depicted the electron gun end ll of a traveling wave tube for purposes of illustrating the position of the cathode assembly of the present invention.
  • That portion 11 of the traveling wave tube which is shown comprises a metallic envelope portion 13 within which is mounted, by means of a mounting member M, the electron gun assembly 16.
  • Gun assembly 16 comprises a cathode shield 17, within which is mounted the cathode assembly 12 of the present invention, and further comprises a beam forming electrode 13 and an acceleratint anode 19 which is maintained in spaced relation to the beam forming electrode by mem er 2 ⁇ ; and post 22.
  • the base end of the envelope portion 13 is sealed by means of plate 23 of glass or other suitable material and tubulation 24.
  • the gun end of member 11 is sealed to a glass envelope portion 26 which contains the helix, not shown, of the traveling wave tube.
  • FIG. 2 there is shown in detail a section through the cathode assembly 12 of the present invention. inasmuch as a sectional view, while adequate for showing the various elements and parts of the cathode structure, does not give a three-dimensional aspect to the structure, which in the case of the present invention is highly desirable, in the following description of FIG. 2 reference should also be made to FIGS. 3 and 4 35 so that a clear understanding of the cathode structure may be had.
  • Cathode assembly 12 comprises a tubular member 31 of nickel or other suitable material at the upper end of which, as viewed in FIG. 2, is attached a cap 32.
  • the surface 33 of cap 32 is coated with electron emissive material such as barium and strontium carbonate.
  • Cap 32 is attached to member 31 preferably by welding.
  • Tubular member 31 is provided with enlarged portions 34 at each end thereof, which are bored out to form shoulders 36 at both the upper and lower ends of member 31.
  • Enlarged portions 34 have a plurality of slots 37 therein which are best seen in FIG. 3 where, in the embodiment shown, each enlarged portion 34 has four slots.
  • Cap member 32 likewise has four slots 38, which are circumferentially disposed so as to mate with slots 37 when member 31 and member 32 are assembled and welded.
  • a core 39 of molybdenum or other suitable material which has an insulating coating 41 of aluminum oxide thereon, and has an enlarged flange portion 42 which butts against shoulder 36 of member 31.
  • Flange 42 is welded to member 31 to maintain core 39 in proper position.
  • a double helix heater 43 of tungsten or other suitable material, having an insulating coating of aluminum oxide thereon.
  • One lead 44 of heater 43 passes through an aperture 46 in flange 42 and through an aperture 47 in a washer 43, the purpose of Which will be explained more fully hereinafter.
  • the other lead, not shown, of heater 43 may be attached to member 31 as by Welding or it may be brought out through flange 42 and washer 48 in the same manner as lead 44.
  • a plate 49 rests on shoulder 36 and is Welded to member 31 in the same manner as flange 42.
  • a washer 51 is likewise situated in the bore of the enlarged portion 34 of member 31.
  • a shell 52 of molybdenum or other suitable material Surrounding the tubular member 31 and cap 32 is a shell 52 of molybdenum or other suitable material, which, as best seen in FIG. 4, comprises a member having a large slot 53 cut in one side thereof to a depth extending past the center line of the cylinder, thereby forming a first cylindrical portion 54 which surrounds members 31 and 32, and a second cylindrical portion 56 through which the necessary voltage leads extend. Portion 54 is bored out to form a first shoulder 57 and a second smaller shoulder 58.
  • mounting member 61 Within member 54 and resting on shoulder 57 is a mounting member 61, which will be discussed more fully hereinafter.
  • Mounting member 61 has a pair of keyways 62 cut therein, as best seen in FIG. 4, and resting upon mounting member 61 is a retaining ring 63 which has a pair of keys 64 which mate with keyways 62.
  • Retaining ring 63 is, in turn, retained in position by a castellation 66, which comprises a ring of nickel having a plurality of lugs 67 which are bent over and reside in slots 68 in member 63.
  • Castellation 66 rests upon shoulder 58 in member 52 and is joined to member 52 as by welding.
  • Support member 61 as best seen in FIG. 4, comprises a cylindrical member of molybdenum which has a pcripheral V-shapcd groove 69 located midway between the two end faces of the member.
  • Each end face of the member 61 has a pair of diametrically opposed keyways 62, the purpose of which has already been pointed out.
  • each end face of member 61 has two pairs of diametrically opposed V-shaped slots 71.
  • Each pair of slots 71 may be oriented 90 degrees with respect to the other, or any other suitable angle may be chosen depending upon the ease of fabrication. The angle between the pairs of slots should not, however, be too small.
  • each of the slots 71 and longitudinally of the member 61 Extending from each of the slots 71 and longitudinally of the member 61 is a V-shaped groove 72, which extends to the other end face or" the member 61 so that each slot 71 on one end face 'is joined to ing slot 71 on the other end face.
  • Tubular member 31 is supported within the supporting member 61 by means of fine support wires 73 and 74, which are of a material such as Nilvar which has a low thermal conductivity and a high tensile strength.
  • the manner in which the wires 73 and 74 act as a support can best be understood by a brief explanation of the manner in which they are wound relative to member 61 and member 31.
  • Wire 73 for example, is welded at one end to support member 61 at the bottom thereof, as best seen in FIG. 2. The wire is then passed through a longitudinally extending V-shaped slot 72, through the corresponding V-shaped slot 71 on the left-hand end face of member 61, as viewed in FIG. 4.
  • a molybdenum wire is wound in groove 69 in member 61 to compress the wires 73 and 74 slightly within the groove 69, thereby increasing the tension on wires 73 and 74 to the desired value.
  • the tension on the wires should be sufiiciently less than the yield point of the material to allow for thermal expansion and contraction of the wire without deformation.
  • the base portion 56 of member 52 has mounted therein three metallic lead lugs 76, 77 and 78, as seen in FIG. 2.
  • Lug 76 serves as a lead-in conductor for heater lead 44 and is joined thereto by means of a lead 79.
  • Either of lugs 77 or 78 may be used as another lead-in conductor for the other heater lead if it is so desired, although in the embodiment here shown, as pointed out before, the other heater lead is simply joined to the member 31.
  • lugs 77 and 78 are connected by means of thermal couple leads 81 and 82, respectively, to the member 31.
  • the thermal couple leads permit monitoring of the cathode temperature so that the precise the correspondrelationship between power drain and cathode temperature for each individual tube may be readily determined. Other than this, the thermal couple leads are not used.
  • FIG. 5 there is depicted schematic-ally the tubular member 31, the support member 61 and wire 73 for purposes of illustrating some of the operational stresses which the elements undergo during various stages of fabrication and during operation.
  • the member 31, the support 61 and the wire 73 are oriented relative to each other as shown by the solid lines.
  • the members 31 and 61 and the wire '73 will all expand to the position shown by the dotted lines and the wire will extend along the path A, B, C, D, E, F, G and H.
  • the member 61 does not expand but the member 31 does and the wire 73 will lie along the path A, B, C, D, E, P, G, H.
  • the cathode of the present invention achieves the objects for which it was made.
  • the Nilvar Wires because of their small diameter and the low heat conductivity of Nilvar, present very high impedance paths to heat flow and the principal heat losses in the cathode are due to radiation, whereas in conventional cathodes conduction losses are at least eighty percent of the total heat loss.
  • the power drain of the cathode is quite small, in the actual structures thus far made a power of one watt is sufiicient to heat the cathode to well over 700 degrees C. which is the operating temperature of the cathode.
  • Conventional cathode structures used in travelling Wave tubes require from five to ten watts of power to heat the cathode to this operating temperature.
  • the structural strength of the cathode assembly surpass the strength of most conventional cathode structures. Tests thus far have proven the cathode structure of the present invention to be capable of withstanding acceleration forces greater than 40 Gs at frequencies between 50 c.p.s. and 3,000 c.p.s. Because of the plate 32 being mounted at one end of the member 31 and no compensating weight being mounted at the other end of member 31, the center of gravity of the assembly of members 31, 32, 39 and 43 is toward the emission end. Ordinarily this would make the assembly more susceptible to vibration than if the center of gravity were exactly centered in the assembly, but inasmuch as each of the wires 73 and 74 passes over the upper end of member 31, as viewed in FIG. 2, twice, thereby in effect giving eight columnar supports for the upper end and a consequent greater rigidity, vibrational etfects are minimized.
  • the core member 39 and its insulating coating 41 are of a diameter such that the heater coil 43 is closer to the core than to the inside walls of member 31. T herefore, if the heater vibrates during operation it cannot vibrate sufficiently far to strike the walls of member 31.
  • a cathod structure comprising a tubular member having an electron emissive surface at one end thereof, a heater within said tubular member, and a supporting structure for said tubular member comprising a slotted annular member surrounding said tubular member and spaced therefrom, and a plurality of stressed wires, each of said wires extending from the slots in said annular member to both of the ends of said tubular member, the ends of said wires being secured to said annular member.
  • a cathode structure comprising a tubular member having an electron emissive surface at one end thereof and a plurality of slots in said tubular member adjacent the electron emissive end and at the opposite end thereof, a heater within said tubular member, and a supporting structure for said tubular member comprising a slotted annular member surrounding said tubular member and spaced therefrom, and a plurality of stressed wires each of said wires extending from the slots in said annular member and through the slots in both of the ends of said tubular member the ends of said wires being secured to said annular member.
  • a cathode structure as claimed in claim 2 wherein said wires are of a material having sufiicient resistance to the conduc tion of heat to minimize heat losses and having a tensile strength suflicient to prevent deformation due to thermal expansion and contraction.
  • a cathode structure comprising a tubular member having a plurality of slots at each end thereof, an electron emissive cap ember having slots therein which match with the slots in one end of said tubular member, said cap member being affixed to said one end, a heater within said tubular member, and a support structure for said tubular member comprising a slotted annular member surrounding said tubular member and spaced therefrom, and a plurality of stressed wires each of said wires extending from the slots in said annular member through the slots at each end of said tubular member, and a cylindrical shell of metallic material within which said support member is mounted, the ends of said wires being secured to said annular member.
  • a cathode structure comprising a cylindrical member having an electron emissive surface mounted on one end thereof and a supporting structure for said cylindrical member comprising a slotted annular member surrounding said cylindrical member and spaced therefrom, and a plurality of stressed wires each of said wires extending from the electron emissive end of said cylindrical member through the slots in said annular member, the ends of said wires being affixed to said annular member.
  • a cathode structure as claimed in claim 5 wherein said wires are of a material having suiiicient resistance to the conduction of heat to minimizing heat losses and having a tensile strength sufficient to prevent deformation due to thermal expansion and contraction.
  • a supporting structure for an electron emissive cathode comprising a cathode, a plurality of wire loops, the wires of said loops passing through slots in an annular member surrounding said cathode whereby said wires are held under tension, the cathode being mounted within said loops and in contact therewith adjacent the ends of said cathode.
  • wires forming said loops are of a material having sufficient resistance to the conduction of heat to minimize heat losses and having a tensile strength sufficient to traction.
  • a cathode structure comprising a hollow cylindrical member having an electron emissive cap mounted at one end thereof, a heater within said cylindrical member, and a supporting structure for said cylindrical member and said cap comprising a slotted annular member surrounding said cylindrical member and spaced therefrom, and a plurality of stressed Wires extending from the slots in said annular member to both of the ends of said cylindrical member at an angle to said cylindrical member, the angle formed between said wires and said cylindrical member being so chosen that said Wires are subjected to tensile and compressive stresses only during the operation of said cathode, each of said Wires being secured to said annular member.

Landscapes

  • Microwave Tubes (AREA)
US95677A 1961-03-14 1961-03-14 Cathode structure Expired - Lifetime US3167679A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
FR1317679D FR1317679A (enrdf_load_stackoverflow) 1961-03-14
US95677A US3167679A (en) 1961-03-14 1961-03-14 Cathode structure
GB7962/62A GB990690A (en) 1961-03-14 1962-03-01 Cathode structure for use in electron discharge devices
DEW31839A DE1298645B (de) 1961-03-14 1962-03-13 Kathodenanordnung, insbesondere fuer Laufzeitroehren

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US95677A US3167679A (en) 1961-03-14 1961-03-14 Cathode structure

Publications (1)

Publication Number Publication Date
US3167679A true US3167679A (en) 1965-01-26

Family

ID=22253101

Family Applications (1)

Application Number Title Priority Date Filing Date
US95677A Expired - Lifetime US3167679A (en) 1961-03-14 1961-03-14 Cathode structure

Country Status (4)

Country Link
US (1) US3167679A (enrdf_load_stackoverflow)
DE (1) DE1298645B (enrdf_load_stackoverflow)
FR (1) FR1317679A (enrdf_load_stackoverflow)
GB (1) GB990690A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3766487A (en) * 1969-11-27 1973-10-16 Lasers Co Ind Des Discharge tube with dismountable electrode

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE22378E (en) * 1943-09-21 Electron gun structure and method
US2397233A (en) * 1943-12-14 1946-03-26 Philco Radio & Television Corp Grid structure for vacuum tubes and the like
US2861211A (en) * 1954-06-29 1958-11-18 Int Standard Electric Corp Pre-stressed grids for electron tubes
US2874209A (en) * 1953-01-21 1959-02-17 Philips Corp Support or stay member for parts of the electrode systems of electric discharge tubes
DE1098622B (de) * 1956-07-25 1961-02-02 Egyesuelt Izzolampa Impraegnierte Vorratskathode oder L-Kathode
US3105165A (en) * 1960-08-08 1963-09-24 Sylvania Electric Prod Electrode spacer

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE22378E (en) * 1943-09-21 Electron gun structure and method
US2397233A (en) * 1943-12-14 1946-03-26 Philco Radio & Television Corp Grid structure for vacuum tubes and the like
US2874209A (en) * 1953-01-21 1959-02-17 Philips Corp Support or stay member for parts of the electrode systems of electric discharge tubes
US2861211A (en) * 1954-06-29 1958-11-18 Int Standard Electric Corp Pre-stressed grids for electron tubes
DE1098622B (de) * 1956-07-25 1961-02-02 Egyesuelt Izzolampa Impraegnierte Vorratskathode oder L-Kathode
US3105165A (en) * 1960-08-08 1963-09-24 Sylvania Electric Prod Electrode spacer

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3766487A (en) * 1969-11-27 1973-10-16 Lasers Co Ind Des Discharge tube with dismountable electrode

Also Published As

Publication number Publication date
GB990690A (en) 1965-04-28
FR1317679A (enrdf_load_stackoverflow) 1963-05-10
DE1298645B (de) 1969-07-03

Similar Documents

Publication Publication Date Title
US2414785A (en) High-frequency tube structure
US2353743A (en) High-frequency electronic discharge device
US2367332A (en) Cathode
US2815467A (en) High frequency tube
US2914694A (en) Cathode assembly
US2282392A (en) Electron discharge device
US2335818A (en) Cathode assembly
US3134923A (en) Plural parallel electron-guns
US2542639A (en) Electrode structure for electric discharge devices
US2513277A (en) Electron discharge device, including a tunable cavity resonator
US3167679A (en) Cathode structure
US4558250A (en) Cathode structure of electron tube
US2111506A (en) Cathode structure
US3813571A (en) Insulated cathode gun device
US2321886A (en) Electron discharge device
US2818528A (en) Electron discharge device
US2412800A (en) Electron discharge device
US2081415A (en) Electron emitter
US2428609A (en) High-frequency electric discharge device
US3145318A (en) Cathode grid assembly for electron gun
US2860285A (en) Electron discharge devices
US2423161A (en) Electron discharge device of the plural cavity resonator type
US3814976A (en) Thermionic emission device having thermal expansion compensating means
US2580988A (en) Electron discharge device
US2411523A (en) Electron discharge device