US3806755A - Electron collector having means for reducing secondary electron interference in a linear beam microwave tube - Google Patents

Electron collector having means for reducing secondary electron interference in a linear beam microwave tube Download PDF

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Publication number
US3806755A
US3806755A US00258305A US25830572A US3806755A US 3806755 A US3806755 A US 3806755A US 00258305 A US00258305 A US 00258305A US 25830572 A US25830572 A US 25830572A US 3806755 A US3806755 A US 3806755A
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United States
Prior art keywords
collector
electrons
tube
impact surface
downstream end
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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
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US00258305A
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English (en)
Inventor
E Lien
M Levin
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Varian Medical Systems Inc
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Varian Associates Inc
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Publication date
Application filed by Varian Associates Inc filed Critical Varian Associates Inc
Priority to US00258305A priority Critical patent/US3806755A/en
Priority to FR7318691A priority patent/FR2186729B1/fr
Priority to JP6077173A priority patent/JPS576657B2/ja
Priority to DE2327665A priority patent/DE2327665C2/de
Priority to CA172,734A priority patent/CA973635A/en
Priority to GB2604273A priority patent/GB1394042A/en
Priority to NLAANVRAGE7307637,A priority patent/NL183373C/xx
Application granted granted Critical
Publication of US3806755A publication Critical patent/US3806755A/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
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/027—Collectors

Definitions

  • the approaches for eliminating or significantly reducing the number and effect of high speed secondary electrons returning from the collector fall into three categories: (1) reduction of the number of high speed secondary electrons produced by beam impact within the collector; (2) reduction of the percentage of high speed secondary electrons produced in the collector which can escape into the interaction section of the tube; (3) reduction of themodulation on the secondary electrons, or at least that portion of it which falls within the frequency range of interest.
  • the measures introduced according to the present invention attack the secondary electron problem along each of these three lines.
  • collector having a domed end surface portion.
  • the collector is dimensioned in such a way that beam divergence causes impact well up on the virtually cylindrical sidewall of the collector.
  • collector designs are known in which the end wall of of the collector is a portion of a sphere, particularly a hemisphere. However, in each of these designs known to applicant, a substantial portion of the electrons impact on the cylindrical sidewall of the collector.
  • the efiect on the performance of linear beam microwave tubes of secondary electrons emanating from the collector can be eliminated or substantially reduced by providing, at the downstream end of the collector, an electron impact surface which is substantially the locus of points equidistant from the constricted upstream mouth of the collector.
  • the percentage of the secondary electrons that are produced within the collector and which can return'to the interaction section of the tube is reduced, because the e gion wherein these secondary electrons are generated is removed as far as possible from the mouth of the collector.
  • modulation of the beam of electrons which causes a proportional degree of spreading of the beam within the collector at the modulation frequency, does not result in a corresponding modulation of the secondary electrons.
  • a significant reduction in the total number of high speed secondary electrons produced is realized by coating the impact surface portion of the collector with a material of low atomic weight.
  • the principal object of the present invention is to provide an improved linear beam microwave tube in which the number and effect of secondary electrons returning from the collector region to the interaction region of the tube is significantly reduced.
  • OBJECTS comprises a peripheral truncated conical surface having the large end facing upstream and an end plate closing the downstream end.
  • FIG. 1 is a cross sectional view partly in schematic line diagram form of a prior art UHF multicavity klystron amplifier
  • FIG. 2 is an enlarged detailed view of an electron collector illustrating theprinciples of the present invention.
  • the tube 1 includes a conventional electron gun assembly 2 for forming and projecting a beam of electrons 3 over an elongated beam path 4 to the conventional beam collector assembly 5.
  • An input signal to be amplified is fed into the input cavity resonator 6 via input coupling loop assembly 7 and input coaxial line 8.
  • a segmented drift tube tunnel 9 through which beam 3 passes, communicates between successive cavity resonators 6.
  • the mutually opposed ends of the drift tube tunnel segments, projecting 7 into each of the cavity resonators 6, define electronic interaction gaps 11.
  • An input signal supplied to the input cavity resonator 6 excites resonance of the input cavity 6, developing an alternating electric field across input gap 11'.
  • the electric field of gap 11 velocity modulates the beam 3.
  • this velocity modulation is converted within the drift space to current density modulation which excites resonance of the next two driver cavities 6".
  • These two succeeding driver cavities further velocity modulate the beam 3 which velocity modulation is converted in drift tunnel 9 into increased current density modulation of the beam 3 as the electrons move toward the collector 5.
  • the electron gun tube produced a beam 3 having a beam voltage of 18 kv. and 4.8 amperes with a perveance of 2 X 10".
  • the cathode emitter 17 had an emission density of 0.8 amps/centimeter sq. of emitting surface.
  • the cavities 6 were cylindrical with an inside diameter of 8 inches and a length of 5.4 inches.
  • the drift tube tunnel segments 9 were of copper and had an internal diameter of 0.875 inches and an outside diameter of 1.475 inches.
  • the collector 5 comprises a solid cylindrical block, as of copper, having a central cylindrical bore 18 terminating in a tapered end portion 19, the whole being insulatedly mounted from the main body of the tube 1.
  • the collector would typically be operated at ground (0v) potential, and would be provided with a liquid cooling means surrounding its exterior surface (not shown). Since the collector region comprises an electric-field-free space which additionally has a very low value of magnetic field strength, the beam rapidly diverges upon entering the collector region under the influence of space charge forces.
  • the beam electrons Upon striking the collector surface 18 19, the beam electrons give rise to a certain percentage of secondary (impact-produced) electrons which are liberated in the collector region space with varying velocities and directions. However, for reasons of no concern to the present invention, these electrons are rather sharply divided into a high speed group and a low speed group. A certain percentage of the high speed electrons will have sufficient energy and will be released in the proper direction to return to the interaction section of the tube, following a reverse path to that of the beam electrons. a
  • the density and velocity of elecrons arriving at the collector varies greatly with time.
  • the beam density is very high and/or the axial velocity low at the collector mouth, the beam diverges rapidly in its travel down the collector under the influence of rather large space charge forces, in addition to the radial deflection produced at the exit from the magnetic focusing field. Accordingly, a relatively large number of electrons from the beam will strike the collector near the mouth as illustrated by the path marked A.
  • any high speed secondary electrons generated by the impact of beam electrons following the path A will be released relatively close to the mouth of the collector and will have a relatively high probability of returning to the interaction section of the tube 1. Conversely, at instants of time when the beam density arriving at the collector is very low, or the axial electron velocity high, the beam divergence will be less, resulting in electron trajectories more nearly along the path B in FIG. 1. High speed secondary electrons generated by beam electrons on path B will have a relatively low probability of returning to the interaction section of the tube. Since, as noted, the density of primary electrons will be modulated at both the rf and signal frequencies,-it is clear from the above that the points at which the beam electrons hit the cylindrical surface 18 of the collector will vary in response to both frequencies.
  • the collector 5 comprises a front plate 20 which is insulatedly and vacuum tightly. joined to the body of tube 1 and defines a constricted central entrance opening 21 which is supported in registration with a tapered output drift tube tunnel section 22 of the tube 1.
  • a front plate 20 To the downstream face of a front plate 20 are joined in succession a series of three substantially cylindrical ring members 23.
  • an end wall assembly 24 closes the open end of member 23.
  • Members 20, 23 and 24 may be made of oxygen-free high conductivity copper brazed together.
  • the end wall assembly 24 is fundamentally comprised of a peripheral portion 25 which is substantially a right truncated.
  • the end wall assembly 24 is dimensioned and positioned with respect to the remaining parts of the tube such that under conditions of the maximum beam divergence to be encountered in the tube, indicated by limiting lines L, still all of the electrons of the beam will impact upon portion 24. Practically speaking, this means simply that the further assembly 24 is positioned from mouth portion 21, the larger assembly 24 must be.
  • a (second) design criterion is that all of the points on impact surface portion 24 should insofar as practicable lie on the locus of points equidistant from point C which is at the center of the midplane of the constricted mouth portion 21 of the collector.
  • the importance of this criterion may be appeciated in view of the foregoing discussion of modulation of secondary electrons in particular when different degress of beam divergence within the collector 5 result in the generation of electrons over a relatively large range of distances from the mouth of the collector as in the prior art collector 5 of FIG. 1 those secondary electrons that are generated close to the mouth of the collector will have a substantially higher probability of returning to the tube.
  • beam divergence is a function of modulating frequency and also of the rf carrier frequency, it is important to avoid a situation where the distance of impact points from the mouth of the collector also varies at the rf and modulating frequencies. According to the present invention, this is accomplished by insuring that under all conditions of beam divergence electron impact occurs on a surface which is substantially equidistant from the mouth of the collector.
  • such a surface would have the configuration of a sphere centered at point C and such an imaginary surface has been indicated by line S drawn at a radius R from point C.
  • R has been chosen in FIG. 2 such that the deviations A of the actual impact surface portion 25 are identical'so that S can be considered as the trace of a median sphere representing an idealized impact surface.
  • This improved collector design avoids large changes in the distance between the electron impact point on the collector surface and the mouth of the collector as the beam divergence varies. Also, by causing the impact surface portion to form the end of the collector, all beam impaction occurs at a point significantly further removed from the mouth of the collector than in previous designs. Therefore, the quantity of secondary electrons returning to the tube is reduced. The quantity of secondary electrons can moreover be further reduced by applying a coating to the inner surface'portions of impact portion 24 consisting of a material of a low atomic weight such as carbon.
  • a linear beam electron discharge device including, means for forming and projecting a beam of electrons over an elongated beam path extending from an upstream end of said device to a downstream end thereof, means forming a wave-beam interaction circuit arranged axially coextensive with and adjacent to a portion of said beam path for electronic interaction with the beam to.
  • collector means located at a downstream end of said device for collecting said beam of electrons and dissipating the energy thereof, said collector means including an impact surface portion at the downstream end thereof substantially aligned with said beam of electrons, and a constricted entrance portion at the upstream end thereof through which said beam of electrons enters said collector means, said impact surface being within 15 percent of the locus of points equidistant from the center of the mid plane of said constricted entrance portion, said impact surface portion being dimensioned and positioned to receive substantially all of the electrons of said beam.
  • said impact surface portion comprises a peripheral truncated conical surface portion having the large end thereof facing upstream, and an end plate portion closing the downstream end thereof.
  • said electron discharge device is a multicavity amplifier tube
  • said wave-beam interaction circuit comprises a plurality of cavity resonators aligned with and encompassing the beam path, and further including a series of axially aligned drift tube tunnels interconnecting adjacent cavities of said cavity resonator in alignment with the beam passing therethrough, said drift tube tunnels having mutually opposed end portions extending reentrantly into said cavity resonators to define electronic interaction gaps therebetween, and means at an upstream end of said wave-beam interaction circuit for introducing an input signal to be amplified.
  • a linear electron beam microwave tube designed for operation within predetermined specifications; means for forming and projecting said beam of electrons over an elongated path extending to a downstream end thereof; means for velocity modulating said beam; and collector means located at the downstream end of said tube for collecting said velocity modulated beam of electrons, said collector means having a given longitudinal axis, electrons in said beam being dispersed in said collector means transversely of said axis according to the velocity modulation of said beam, said beam dispersal having a maximum for tube operation within said predetermined specifications, said collector means including an impact surface at the downstream end thereof, said surface being intersected by said axis, said collector means further including a constricted entrance at the upstream end thereof through which said beam of electrons enters said collector means, said impact surface being defined by the locus of points substantially equidistant from the center of the midplane of said entrance and extending transversely of said axis for a selected distance in proportion to said maximum beam dispersion, said collector means further including means for mounting said

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US00258305A 1972-05-31 1972-05-31 Electron collector having means for reducing secondary electron interference in a linear beam microwave tube Expired - Lifetime US3806755A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US00258305A US3806755A (en) 1972-05-31 1972-05-31 Electron collector having means for reducing secondary electron interference in a linear beam microwave tube
FR7318691A FR2186729B1 (enrdf_load_stackoverflow) 1972-05-31 1973-05-23
JP6077173A JPS576657B2 (enrdf_load_stackoverflow) 1972-05-31 1973-05-30
DE2327665A DE2327665C2 (de) 1972-05-31 1973-05-30 Auffangvorrichtung für einen Elektronenstrahl
CA172,734A CA973635A (en) 1972-05-31 1973-05-30 Electron collector having means for reducing secondary electron interference in a linear beam microwave tube
GB2604273A GB1394042A (en) 1972-05-31 1973-05-31 Electron collector having means for reducing secondary electron interference in a linear beam microwave tube
NLAANVRAGE7307637,A NL183373C (nl) 1972-05-31 1973-06-01 Inrichting voor het afgeven van een lineaire elektronenbundel.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00258305A US3806755A (en) 1972-05-31 1972-05-31 Electron collector having means for reducing secondary electron interference in a linear beam microwave tube

Publications (1)

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US3806755A true US3806755A (en) 1974-04-23

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US00258305A Expired - Lifetime US3806755A (en) 1972-05-31 1972-05-31 Electron collector having means for reducing secondary electron interference in a linear beam microwave tube

Country Status (7)

Country Link
US (1) US3806755A (enrdf_load_stackoverflow)
JP (1) JPS576657B2 (enrdf_load_stackoverflow)
CA (1) CA973635A (enrdf_load_stackoverflow)
DE (1) DE2327665C2 (enrdf_load_stackoverflow)
FR (1) FR2186729B1 (enrdf_load_stackoverflow)
GB (1) GB1394042A (enrdf_load_stackoverflow)
NL (1) NL183373C (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3925701A (en) * 1973-11-08 1975-12-09 Siemens Ag Electron beam collector electrode for an electron beam tube
US3936695A (en) * 1974-04-26 1976-02-03 Varian Associates Electron collector having means for trapping secondary electrons in a linear beam microwave tube
DE3334520A1 (de) * 1982-09-27 1984-03-29 Varian Associates, Inc., 94303 Palo Alto, Calif. Linearstrahl-elektronenroehre
US5942852A (en) * 1997-06-05 1999-08-24 Hughes Electronics Corporation Efficient, highly linear traveling wave tube using collector with high backstreaming current under saturated drive
US20050130550A1 (en) * 2001-12-20 2005-06-16 Pascal Ponard Method for making electrodes and vacuum tube using same
US20050189881A1 (en) * 2004-02-27 2005-09-01 E2V Technologies Limited Collector arrangement
US20150060052A1 (en) * 2013-09-04 2015-03-05 Qmast Llc Sheet beam klystron (sbk) amplifiers with wrap-on solenoid for stable operation

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103808990B (zh) * 2014-03-06 2016-09-21 中国科学院电子学研究所 具有减小电场畸变功能的容性探针装置
CN103794449B (zh) * 2014-03-06 2016-02-03 中国科学院电子学研究所 电子注轴向速度测量系统

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2949558A (en) * 1957-10-21 1960-08-16 Bell Telephone Labor Inc High efficiency velocity modulation devices
US3116435A (en) * 1959-07-28 1963-12-31 Eitel Mccullough Inc Velocity modulation tube
US3388281A (en) * 1964-08-07 1968-06-11 Thomson Houston Comp Francaise Electron beam tube having a collector electrode insulatively supported by a cooling chamber
US3421036A (en) * 1965-09-21 1969-01-07 Siemens Ag Varying inner diameter collector electrode for an electron beam tube,particularly high powered travelling-wave tubes
US3662212A (en) * 1970-07-15 1972-05-09 Sperry Rand Corp Depressed electron beam collector

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1137415A (fr) * 1955-07-13 1957-05-28 Thomson Houston Comp Francaise Paroi, ou surface anodique pour tube à vide fonctionnant par impulsions
DE1491325A1 (de) * 1962-09-07 1969-06-04 Philips Patentverwaltung Elektronenstrahlroehre mit Zylinderfeldfokussierung
US3368104A (en) * 1964-03-17 1968-02-06 Varian Associates Electron beam tube included depressed collector therefor
US3448325A (en) * 1966-09-06 1969-06-03 Varian Associates Linear beam tube having a beam collector cooled by radiation through an infrared window
US3450930A (en) * 1966-11-14 1969-06-17 Varian Associates Permanent magnet focused linear beam tube employing a compensating magnet structure between the main magnet and the beam collector
US3426230A (en) * 1967-04-18 1969-02-04 Webb James E Direct radiation cooling of the collector of linear beam tubes
US3644778A (en) * 1969-10-23 1972-02-22 Gen Electric Reflex depressed collector

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2949558A (en) * 1957-10-21 1960-08-16 Bell Telephone Labor Inc High efficiency velocity modulation devices
US3116435A (en) * 1959-07-28 1963-12-31 Eitel Mccullough Inc Velocity modulation tube
US3388281A (en) * 1964-08-07 1968-06-11 Thomson Houston Comp Francaise Electron beam tube having a collector electrode insulatively supported by a cooling chamber
US3421036A (en) * 1965-09-21 1969-01-07 Siemens Ag Varying inner diameter collector electrode for an electron beam tube,particularly high powered travelling-wave tubes
US3662212A (en) * 1970-07-15 1972-05-09 Sperry Rand Corp Depressed electron beam collector

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3925701A (en) * 1973-11-08 1975-12-09 Siemens Ag Electron beam collector electrode for an electron beam tube
US3936695A (en) * 1974-04-26 1976-02-03 Varian Associates Electron collector having means for trapping secondary electrons in a linear beam microwave tube
DE3334520A1 (de) * 1982-09-27 1984-03-29 Varian Associates, Inc., 94303 Palo Alto, Calif. Linearstrahl-elektronenroehre
US5942852A (en) * 1997-06-05 1999-08-24 Hughes Electronics Corporation Efficient, highly linear traveling wave tube using collector with high backstreaming current under saturated drive
US20050130550A1 (en) * 2001-12-20 2005-06-16 Pascal Ponard Method for making electrodes and vacuum tube using same
US7812540B2 (en) * 2001-12-20 2010-10-12 Thales Method for making electrodes and vacuum tube using same
US20050189881A1 (en) * 2004-02-27 2005-09-01 E2V Technologies Limited Collector arrangement
US20060279219A1 (en) * 2004-02-27 2006-12-14 E2V Technologies (Uk) Limited Collector arrangement
US7230385B2 (en) 2004-02-27 2007-06-12 E2V Technologies (Uk) Limited Collector arrangement
US20150060052A1 (en) * 2013-09-04 2015-03-05 Qmast Llc Sheet beam klystron (sbk) amplifiers with wrap-on solenoid for stable operation
US10490381B2 (en) * 2013-09-04 2019-11-26 Qmast Llc Sheet beam klystron (SBK) amplifiers with wrap-on solenoid for stable operation

Also Published As

Publication number Publication date
FR2186729A1 (enrdf_load_stackoverflow) 1974-01-11
DE2327665C2 (de) 1984-05-03
CA973635A (en) 1975-08-26
GB1394042A (en) 1975-05-14
NL7307637A (enrdf_load_stackoverflow) 1973-12-04
JPS4957762A (enrdf_load_stackoverflow) 1974-06-05
NL183373C (nl) 1988-10-03
FR2186729B1 (enrdf_load_stackoverflow) 1977-02-18
NL183373B (nl) 1988-05-02
JPS576657B2 (enrdf_load_stackoverflow) 1982-02-05
DE2327665A1 (de) 1973-12-13

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