US3390301A - Cavity resonator having alternate apertured drift tubes connected to opposite end walls - Google Patents

Cavity resonator having alternate apertured drift tubes connected to opposite end walls Download PDF

Info

Publication number
US3390301A
US3390301A US512678A US51267865A US3390301A US 3390301 A US3390301 A US 3390301A US 512678 A US512678 A US 512678A US 51267865 A US51267865 A US 51267865A US 3390301 A US3390301 A US 3390301A
Authority
US
United States
Prior art keywords
cavity
resonator
gap
cavity resonator
end walls
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
US512678A
Other languages
English (en)
Inventor
Sawada Ryoka
Kaneko Yoichi
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.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
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
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Application granted granted Critical
Publication of US3390301A publication Critical patent/US3390301A/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
    • H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
    • H01J23/18—Resonators
    • H01J23/20—Cavity resonators; Adjustment or tuning thereof

Definitions

  • This invention relates to cavity resonators.
  • Cavity resonators previously used in klystron amplifiers for microwave frequency bands and particularly for relatively low frequencies have generally been very large in size, having a considerably large outside diameter even in cases of klystrons of relatively low power level. This naturally has resulted in increase in size of the focusing coil to economical disadvantage and, even with high power tubes, it has been extremely difficult to minimize their external dimensions without detracting from their efficiency.
  • Mere reduction in size of cavity resonators may possibly be realized by the method of increasing the electrostatic capacitance of the gaps, where the electron beam and the electric field of the cavity resonator interact, while reducing their inductance. Cavity resonators so designed, however, would be impractical because of reduction in characteristic impedance and increase in power loss.
  • multicavity resonators have also been in use which correspond to a combination of a multitude of single-cavity resonators and have advantages such as increase in frequency bandwidth and reduction in power loss.
  • the multicavity type of resonator provides modes of operation corresponding in number to the cavities included in the resonator and this requires separation of any unwanted modes other than the principal one and thus causes a difficult design problem.
  • This form of cavity resonator includes two posts 2 formed with aligned axial holes 3 for passage therethrough of an electron beam, and carried on opposite conductor walls, which are integral with a hollow conductor casing 1 enclosing the posts.
  • reduction in size of the cavity results in proportional reduction in inductance L and in capacitance C of the resonator.
  • the capacitance C must be increased for the resonator to maintain the same basic resonant frequency.
  • the present invention has for its primary object to provide a cavity resonator reduced in outside diameter.
  • Another object of the present invention is to provide a cavity resonator which provides no unwanted modes of operation in the vicinity of its basic resonant frequency.
  • a further object of the present invention is to provide a cavity resonator which is relatively limited in loss and gives a high gain when employed, for example, in velocity modulation tubes.
  • FIGURES la and 1b provide longitudinal and transverse sectional views, respectively, of a known cavity resonator
  • FIGURES 2a and 2b illustrate one form of multiplegap cavity resonator embodying the present invention
  • FIGURES 3a and 3b illustrate another form of multiple-gap cavity resonator embodying the invention
  • FIGURE 4 illustrates a further form of cavity resonator embodying the present invention
  • FIGURES 5a, 5b, and 5c illustrate various forms of equivalent circuits of the multiple-gap cavity resonator embodying the present invention
  • FIGURES 6 and 7 represent diagrams illustrating the operation of the inventive cavity resonator.
  • FIGURE 8 illustrates a velocity modulation tube for amplification use incorporating a number of cavity resonators embodying the present invention.
  • Reference numeral 5 indicates apertured members formed each with an axial aperture for passage therethrough of an electron beam. These apertured members 5 constitute a modification for multiple-gaps formation of the posts 2 used in the conventional single-gap cavity resonator shown in FIGURES la and 1b and are alternately interconnected by a pair of supporting conductors 6, with a working gap 4 formed between each two adjacent opposing ones of the ape'rtured members. Though the embodiment shown in FIG. 2a has three gaps, it is to be understood that cavity resonators including a greater number of working gaps can also be readily realized.
  • FIG. 5a The equivalent circuit of the cavity resonator shown in FIG. 2a is illustrated in FIG. 5a.
  • Reference characters C C and C indicate the electro-static capacitance of the respective gaps of the resonator, including any additional electro-static capacitance appearing in regions adjacent to the respective gaps.
  • Characters L and L represent the inductances of the respective supporting conductors 6; L represents the inductance of the cavity; and r a series resistance corresponding to the cavity loss. In cases where the inductances L and L of the supporting conductors are relatively limited, the equivalent circuit is approximately illustrated as in FIGS. 5b and 50.
  • the entire capacitance apparently is three times as large as the one for any single gap and, therefore, the cavity inductance L, can be reduced to one-third of that of an equivalent singlegap resonator.
  • this form of cavity resonator can be greatly reduced in cavity size.
  • any unwanted modes other than the basic resonant frequency can be avoided owing to the single-cavity structure of the resonator.
  • FIG. 6 illustrates the electric field distribution in the working gaps 4 of the inventive cavity resonator at an instant during operation, in the case where the resonator has three gaps, as illustrated in FIG. 2a.
  • the distribution of the electric field E is alternately reversed in phase for the successive gaps and the high-frequency exciting fields taking place in the respective gaps have substantially the same amplitude since the apertured members interconnected by either of the supporting conductors are held at substantially the same potential.
  • the magnitude of the voltage appearing in the intermediate gap has been approximately twice as large as those appearing in the remaining gaps.
  • the operation of the cavity resonator when used for velocity modulation of an electron beam will be described, assuming that the resonator includes an odd number 11 of gaps identical in voltage amplitude and alternately reversed in phase of the electric field distributed therein and that the electron transit angle from gap to gap is identical throughout the resonator.
  • V represents the beam voltage
  • Ve represents the highfrequency exciting voltage for each gap
  • [i represents the beam coupling coefficient
  • the power requirement for the multiple-gap cavity, allowing the largest power loss can be substantially equal to that for a single-gap cavity, moreover, with cavity resonators of such structure, an advantage is obtained that for some applications the operable frequency bandwidth can be increased approximately 11 times owing to the low Q of the cavity.
  • FIGURES 3a and 3b illustrate another embodiment of the present invention and in which reference numerals 1, 2, 3, 4 and 6 indicate parts corresponding to those of the embodiment shown in FIGURES 2a and 2b carrying the same reference numerals.
  • each set of alternate apertured members are interconnected by two supporting members, as illustrated.
  • Such structure is not only desirable from the standpoint of mechanical strength but is a so effective to reduce the inductance of the circuit including the effective members compared to the previously described structure, in which alternate apertured members are interconnected by a single supporting conductor.
  • the present invention may also be embodied in various modified forms.
  • supporting conductors associated with any one of the apertured members have not necessarily the same axial length nor are required to be symmetrical.
  • the supporting conductors may have any appropriate configuration while obtaining substantially the same effect as the previously described cavity structures as long as the apertured members arranged alternately are electrically interconnected.
  • appropriate reticulate grid means may be employed to maintain the entire aperture area in an equipotential surface.
  • the cavity resonator according to th present invention has various advantageous features including compactness in size, relatively limited power loss, a wide operational frequency range, lack of unwanted modes is the vicinity of the basic resonant frequency and high gain.
  • FIG. 8 illustrates a velocity modulation tube employing a number of multiple-gap cavity resonators according to the present invention.
  • an input cavity resonator 9, a bunching cavity resonator 10 and an output cavity resonator Ii are arranged in axial alignment in the order named between an electron gun 7 for emitting an electron beam and a collector 8 for collecting the latter after its passage through the resonators.
  • Each of the cavity resonators is constructed ac cording to the present invention and includes a frequency control mechanism 12 in the form of a plate which is disposed in the cavity in opposing relation to the working gaps.
  • the frequency control plate 12 provides an additional capacitance to the gaps and is adjustable to vary the resonant frequency of the resonator.
  • An electromagnetic wave to be amplified is introduced through the coaxial input terminal 13 formed on the input cavity 9 to excite the cavity resonators, applying to the respective gaps exciting voltages alternately opposite in phase and substantially equal to each other.
  • the space between any two adjacent gaps is so established as to give an electron transit angle of approximately 1r radians.
  • velocity modulation can be elfected upon the electron beam with higher efficiency over a frequency range wider than that of a single-gap cavity.
  • the electron hcam is hunched for density modulation before entering the following cavity and,
  • the beam contains all the density modulation components caused in the respective preceding cavities.
  • the energy of the electron beam then leaves the coaxial output terminal 14 formed on the output cavity 11 to be supplied to the external load as a highfrequency exciting power.
  • the Q of the cavity is reduced to further extend the amplification bandwidth because of the positive loading.
  • a negative beam loading can be used as long as it causes no self-excitation by selecting an electron transit angle smaller than 1r radians thereby to further improve the output efficiency.
  • the present invention is applicable not only to amplifier tubes but also has many other applications including microwave oscillators, frequency multipliers, acceleration or deceleration of charged particles and phase focusing, with such advantageous features as compactness in size, high efficiency and wideband characteristics.
  • a cavity resonator comprising a hollow conductor casing including end walls extending at right angles to the axis of said casing, a number of apertured members arranged along the path of charged particles coincident with the axis of said casing so as to define a plurality of gaps therebetween and having aligned apertures for passage therethrough of the charged particles, and supporting conductors interconnecting alternate ones of said apertured members and connected at one end to the respective opposite end walls of said conductor casing in spaced parallel relation to each other to form in said gaps electric fields alternately opposite in phase.
  • a velocity modulation tube of the type including an electron gun for producing a beam of electrons, a collector for collecting said beam of electrons, input, bunching and output cavities arranged between said electron gun and said collector in the order named, a mechanism for introducing an electromagnetic wave into said input cavity, and an output circuit for taking out the electromagnetic Wave amplified, said tube being characterized in that at least one of said cavity comprises a hollow condoctor casing including end walls extending at right angles to the axis of said casing, a number of apertured members arranged along the path of charged particles coincident with the axis of said casing so as to define a plurality of gaps therebetween and having aligned apertures for passage therebetween of the charged particles, and supporting conductors interconnecting alternate ones of said apertured members and connected at one end to the respective opposite end Walls of said conductor casing in spaced and parallel relation to each other to form in said gaps electric fields alternately opposite in phase.

Landscapes

  • Microwave Tubes (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Particle Accelerators (AREA)
US512678A 1964-12-18 1965-12-09 Cavity resonator having alternate apertured drift tubes connected to opposite end walls Expired - Lifetime US3390301A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7106164 1964-12-18

Publications (1)

Publication Number Publication Date
US3390301A true US3390301A (en) 1968-06-25

Family

ID=13449614

Family Applications (1)

Application Number Title Priority Date Filing Date
US512678A Expired - Lifetime US3390301A (en) 1964-12-18 1965-12-09 Cavity resonator having alternate apertured drift tubes connected to opposite end walls

Country Status (4)

Country Link
US (1) US3390301A (fr)
DE (1) DE1491355B2 (fr)
FR (1) FR1459636A (fr)
GB (1) GB1087489A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3509413A (en) * 1966-12-09 1970-04-28 Philips Corp Klystron with added inductance in resonant cavity
US3521116A (en) * 1967-01-31 1970-07-21 Philips Corp Single high-frequency interaction gap klystron with means for increasing the characteristic impedance
US4049995A (en) * 1975-05-07 1977-09-20 English Electric Valve Co., Ltd. Resonant cavity tubes
CN102737929A (zh) * 2011-04-01 2012-10-17 中国科学院电子学研究所 一种滤波器加载宽频带三间隙耦合输出腔结构

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3509413A (en) * 1966-12-09 1970-04-28 Philips Corp Klystron with added inductance in resonant cavity
US3521116A (en) * 1967-01-31 1970-07-21 Philips Corp Single high-frequency interaction gap klystron with means for increasing the characteristic impedance
US4049995A (en) * 1975-05-07 1977-09-20 English Electric Valve Co., Ltd. Resonant cavity tubes
CN102737929A (zh) * 2011-04-01 2012-10-17 中国科学院电子学研究所 一种滤波器加载宽频带三间隙耦合输出腔结构

Also Published As

Publication number Publication date
DE1491355B2 (de) 1972-02-03
DE1491355A1 (fr) 1972-02-03
GB1087489A (en) 1967-10-18
FR1459636A (fr) 1966-11-18

Similar Documents

Publication Publication Date Title
US2725499A (en) High frequency amplifying device
US3221204A (en) Traveling-wave tube with trap means for preventing oscillation at unwanted frequencies
US3221205A (en) Traveling-wave tube with trap means for preventing oscillation at unwanted frequencies
US3324339A (en) Periodic permanent magnet electron beam focusing arrangement for traveling-wave tubes having plural interaction cavities in bore of each annular magnet
US2888597A (en) Travelling wave oscillator tubes
US3453483A (en) Microwave linear beam tube employing an extended interaction resonator operating on an odd pi mode
US3622834A (en) High-efficiency velocity modulation tube employing harmonic prebunching
US3195007A (en) Stagger-tuned klystron with cavities resonant outside passband
US3181024A (en) Traveling-wave tube with oscillation prevention means
CN110491752A (zh) 一种多电子束的绕射辐射振荡器
US2916658A (en) Backward wave tube
US3390301A (en) Cavity resonator having alternate apertured drift tubes connected to opposite end walls
US2952795A (en) Electron discharge device
US3205398A (en) Long-slot coupled wave propagating circuit
US3219873A (en) Microwave electron discharge device having annular resonant cavity
US3248597A (en) Multiple-beam klystron apparatus with periodic alternate capacitance loaded waveguide
US3594606A (en) Velocity modulation tube employing cascaded harmonic prebunching
US3846665A (en) Velocity modulation tube with frequency multiplication for the continuous generation of high power outputs
US3252104A (en) D.c. quadrupole structure for parametric amplifier
US3104340A (en) Broadband klystron
US3054964A (en) Low noise electron beam amplifier with low pump frequency
US3101449A (en) Parametric electron beam devices
US3375397A (en) Extended interaction klystron having inductive coupling means communicating between adjacent cavity resonators
US3594605A (en) Mode suppression means for a clover-leaf slow wave circuit
US3183399A (en) Traveling wave interaction device