US3628084A - Coupled cavity slow wave circuit and tube using same - Google Patents

Coupled cavity slow wave circuit and tube using same Download PDF

Info

Publication number
US3628084A
US3628084A US70197A US3628084DA US3628084A US 3628084 A US3628084 A US 3628084A US 70197 A US70197 A US 70197A US 3628084D A US3628084D A US 3628084DA US 3628084 A US3628084 A US 3628084A
Authority
US
United States
Prior art keywords
coupling slots
slow wave
cavity
slots
array
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
US70197A
Other languages
English (en)
Inventor
Robert J Butwell
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.)
Varian Medical Systems Inc
Original Assignee
Varian Associates 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
Application filed by Varian Associates Inc filed Critical Varian Associates Inc
Application granted granted Critical
Publication of US3628084A publication Critical patent/US3628084A/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
    • H01J23/24—Slow-wave structures, e.g. delay systems

Definitions

  • a plurality of generally radially directed coupling slots are cut through the common wall between adjacent resonators to form a plurality of axially aligned arrays of coupling slots angularly displaced around the beam path.
  • Each axial array of slots is angularly displaced about the beam path from the adjacent array by 360/N degrees where N is the number of axially aligned arrays of slots.
  • Each axially aligned array of coupling slots includes a web portion of the common wall for blocking off a iine-of-sight path parallel to the beam through at least a portion of each array of coupling slots to inhibit cumulative electromagnetic interaction [between undesired beamlets in the arrays of slots and the fields of the slow wave circuit, whereby the efficiency and stability of the tube are increased.
  • cloverleaf slow wave circuits for microwave tubes have included eight arrays of axially aligned coupling slots disposed at 360l8 or 45 intervals about the beam path.
  • the slots provide wave energy communication through an array of cavity resonators sequentially arranged along the beam path to form a slow wave circuit.
  • Such a slow wave circuit is disclosed and claimed in US. Pat. No. 3,233,139 issued Feb. 1, I966 and assigned to the same assignee as the present invention.
  • the angular positioning of the coupling slots in adjacent cavities is rotated by a relatively small angle as of 3 such that each of the arrays of coupling slots transcribes a spiral path rather than a line-of-sight path parallel to the beam through the coupled cavity circuit. Since the electrons are constrained to a straight path parallel to the beam path, due to the magnetic beam focusing field, each of the beamlets is effectively blocked.
  • the principal object of the present invention is the provision of an improved coupled cavity slow wave circuit and microwave tubes using same.
  • One feature of the present invention is the provision, in a coupled cavity slow wave circuit of a microwave tube having N number of angularly displaced axially aligned arrays of coupling slots being equally spaced around the beam path, of N number of end walls having less than N full-sized coupling slots therein, such N number of end walls being angularly arranged for blocking off a line of sight path parallel to the beam path, through at least a portion of each of said axial arrays of coupling slots, whereby undesired beamlets through the coupling slots are blocked to inhibit cumulative electromagnetic interaction between the beamlets and the fields of the slow wave circuit.
  • Another feature of the present invention is the same as the preceding feature wherein there are eight arrays of axially aligned coupling slots disposed at 45 intervals about the beam path and wherein at least eight of the cavity end walls have only seven full-sized coupling slots therein with a solid web portion disposed between the first and seventh coupling slot in each end wall, and wherein the web portions are angularly displaced from the other web portions to block off a line-of-sight path parallel to the beam path through each of the eight axial arrays of coupling slots to interrupt the beamlets therein.
  • each of the coupled cavities comprises a cloverleaf cavity having a generally cloverleaf shape with four inwardly directed nose portions disposed at 45 degree intervals about the axis of the beam.
  • FIG. 1 is a longitudinal sectional view, partly in schematic form, of a prior art microwave tube
  • FIG. 2 is an enlarged sectional view of that portion of the structure of FIG. ll taken along line 22 in the direction of the arrows,
  • FIG. 3 is a plot of power output versus time depicting the waveform for an output pulse derived from the output of the tube of FIG. ll,
  • FIG. 4 is an exploded side elevational view of a portion of the structure of FIG. 1 delineated by line 4-4 and modified to incorporate features of the present invention
  • FIGS. 5A to 5H a series of sectional view of the structure of FIG. 4 taken along section lines A-H, respectively.
  • the microwave tube 1 includes an electron gun assembly 2 for forming and projecting a beam of electrons 3 over an elongated beam path to a beam collector structure 4.
  • a coupled cavity cloverleaf slow wave circuit 5 is disposed along the beam path intermediate the gun 2 and collector 4 for electromagnetic interaction with the beam to produce an am plified output signal.
  • a beam focus solenoid 6 is coaxially disposed of the slow wave circuit 5 for producing an axially directed magnetic field in the beam path 3 for focusing the electron beam through the slow wave circuit 5 to the collector 4.
  • the slow wave circuit 5 includes a plurality of axially aligned cloverleaf coupled cavity resonators 7 successively arranged along the beam path for cumulative electromagnetic interaction with the beam 3.
  • Each cloverleaf cavity 7 includes a pair of axially spaced end walls 8 with an inwardly protruding scalloped sidewall to provide four conductive nose portions 9 inwardly projecting at 45 intervals around the beam path toward the beam axis (see FIG. 2).
  • Adjacent cavity resonators 7 share a common end wall structure 8.
  • the inwardly projecting nose portions 9, in adjacent cavity resonators 7, are angularly displaced about the beam path by 45.
  • a pair of radially directed elongated inductive coupling slots 11 are disposed on opposite sides of the nose portions 9 to provide negative mutual inductive coupling between adjacent cavity resonators 7.
  • the coupling slots 11 are radially elongated for increasing the inductive coupling between adjacent cavities.
  • the inductive coupling slots 11, in the prior art, were axially aligned along a path parallel to the beam path and the eight arrays of coupling slots were located at 45 intervals about the beam path 3.
  • Wave energy to be amplified is applied to the upstream cavity 7 via the intermediary of an input waveguide 12 having a wave permeable vacuumtight window 13 sealed thereacross for maintaining a vacuum within the evacuated microwave circuit 5.
  • the circuit includes a circuit sever 14 which comprises a solid centrally apertured conductive disk without coupling slots to prevent wave energy communication between the upstream slow wave circuit portion and a downstream slow wave circuit portion 16.
  • the disk 14 is centrally apertured to permit passage of the electron beam 3 therethrough.
  • Wave attenuative members 19 and were coupled to the downstream cavity 7 of the upstream circuit portion and the upstream cavity of the downstream portion 16 for absorbing wave energy coupled into the cavities on opposite sides of the sever 14.
  • the microwave energy applied to the upstream cavity establishes a wave on the circuit which cumulatively interacts with the beam to produce bunching thereof.
  • the bunched beam passes from the upstream circuit portion 15 into the downstream circuit portion 16 for exciting a growing wave in the downstream circuit portion 16.
  • the wave in the downstream portion 16 cumulatively interacts with the bunched beam to produce a growing wave on the downstream circuit portion 16.
  • Output wave energy is extracted from the downstream end of the downstream circuit portion 16 via an output waveguide 17 which is sealed by a wave-permeable gastight window assembly 18.
  • the RF output energy extracted from the waveguide 17 is fed to a suitable load, not shown.
  • each of the slotted end walls 8 includes only seven of the eight inductive coupling slots 11.
  • the seven slots 11 are arranged in axial alignment with the eight arrays of slots, i.e., one every 45 of are about the axis of the beam with the exception that one of the slots is omitted in each of the end walls 8.
  • the successive cavities 7 are stacked into the longitudinal array with the nose portions 9 in adjacent resonators angularly displaced relative to each other about the axis of the beam 3 by 45.
  • the cavities 7 and end walls 8 are aligned on eight aligning rods passing through aligning apertures 23 provided in the outer margin or lip of the cavity resonators 7 and end walls 8. In this manner precise angular alignment of the successive cavities 7 and end walls 8 is obtained.
  • the common end walls 8 are all identical but the angular position of the missing slot portion 22 is displaced relative to the other end walls in the set of eight such that the missing slot 22 takes up each of the eight possible positions according to eight angular positions of the individual axial arrays of coupling slots 11, such as to efiectively block a line-of-sight path through each of the eight axial arrays of coupling slots 11.
  • the angular position, about the axis of the beam for the missing slot 22 advances by 45 for each of successive resonators 7 taken in the direction of the beam through the longitudinal array of resonator 7. In this manner the missing slot advances in a spiral position throughout the array of resonator 7.
  • the number of missing slots 22 per resonator be reduced to a minimum, such as one missing slot 22 per end wall 8, in order to maintain the inductive coupling between successive resonators at as high a value as possible.
  • the preferred embodiment for an eight-slot coupled cavity array, employs seven slots 11 in each of the common end walls 8, as shown in FIGS. 4 and 5.
  • FIGS. 4 and 5 for blocking the beamlets through the coupled cavity slow wave circuit 5 is particularly advantageous because all of the end walls 8 are identical and merely assembled in different angular positions to define the composite coupled cavity slow wave circuit 5.
  • the missing slot web portion 22 need not cover the entire missing slot but may, in an alternative embodiment, adequately serve the purpose by blocking off the inner half of the slot 11.
  • the missing slot portion of web 22 may comprise only a partial missing slot.
  • the electric fields of the wave decrease in intensity.
  • the requirement for blocking off the individual arrays of coupling slots decreases. Therefore, the missing slot web portion 22 in the end walls 8 may be omitted near the upstream end of the slow wave circuit 5, such as in the upstream circuit portion 15.
  • the upstream portion 15 of the slow wave circuit 5 is replaced by a succession of klystron-type buncher cavities.
  • the downstream circuit portion 16 serves as the output circuit.
  • the missing slot web portion of the present invention is used to advantage to increase efficiency and to prevent arcing in such a hybrid tube.
  • slow wave circuit means for projecting a beam of electrons over an elongated beam path, slow wave circuit means disposed along the beam path in electromagnetic energy exchanging relation with the beam, said slow wave circuit means including an array of cavity resonators arranged successively along the beam path with adjacent ones of said cavity resonators having common end wall structures, said common end wall structures having a plurality of generally radially directed elongated inductive coupling slots therein providing wave energy communication through said common end walls, said coupling slots being arranged in N angularly displaced axially aligned arrays around the beam path, each array being angularly displaced by 360/N where N is an integral number greater than 2, and wherein at least N number of end walls have less than N number of full-sized coupling slots therein defining a missing slot web portion of each of said end walls, said N number of end walls being arranged for blocking off at least a portion of a line-of-sight path parallel to the beam path through each of said slow wave circuit means including an array of cavity reson
  • N 8 and eight end walls have seven coupling slots therein and wherein the web portion of each of the common walls between the first and the seventh coupling slots in each end wall is angularly displaced by n 360IN relative to each of the other eight end walls, where n is an integral number.
  • each cavity resonator includes four conductive nose portions protruding radially into said cavity resonator from the sidewall thereof, said nose portions being angularly displaced about the beam axis from the adjacent noses by 90 to form a generally cloverleaf cavity geometric configuration, and said nose portions in adjacent cavity resonators being angularly displaced about the beam axis by 45 4.
  • a tube employing a coupled cavity slow wave circuit, means for projecting a beam of electrons over an elongated beam path, slow wave circuit means disposed along the beam path in electromagnetic energy exchanging relation with the beam, said slow wave circuit means including an array of cavity resonators arranged successively along the beam path with adjacent ones of said cavity resonators having common end wall structures, said common end wall structures having a plurality of generally radially directed elongated inductive coupling slots therein providing wave energy communication through said common and walls, said coupling slots being arranged in N angularly displaced axially aligned arrays around the beam path, each array being angularly displaced from the adjacent array by 360IN where N is an integral number greater than 2, and wherein a plurality of said end walls have less than N number of full-sized coupling slots therein defining a missing slot web portion of each of said end walls, said plurality of end walls being arranged such that said missing slot web portions blocking off at least a portion of a line-of-sight path parallel
  • N 8 and eight end walls have seven coupling slots therein and wherein the web portion of each of the common walls between the first and the seventh coupling slots in each end wall is angularly displaced by n 360/N relative to each of the other eight end walls, where n is an integral number.
  • each cavity resonator includes four conductive nose portions protruding radially into said cavity resonator from the side wall thereof, said nose portions being angularly displaced about the beam axis from the adjacent noses by to form a generally cloverleaf cavity geometric configuration, and said nose portions in adjacent cavity resonators being angularly displaced about the beam axis by 45.

Landscapes

  • Microwave Tubes (AREA)
US70197A 1970-09-08 1970-09-08 Coupled cavity slow wave circuit and tube using same Expired - Lifetime US3628084A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US7019770A 1970-09-08 1970-09-08

Publications (1)

Publication Number Publication Date
US3628084A true US3628084A (en) 1971-12-14

Family

ID=22093761

Family Applications (1)

Application Number Title Priority Date Filing Date
US70197A Expired - Lifetime US3628084A (en) 1970-09-08 1970-09-08 Coupled cavity slow wave circuit and tube using same

Country Status (6)

Country Link
US (1) US3628084A (fr)
CA (1) CA939812A (fr)
DE (1) DE2142869A1 (fr)
FR (1) FR2107128A5 (fr)
GB (1) GB1361833A (fr)
IL (1) IL37440A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150171502A1 (en) * 2008-08-12 2015-06-18 Lockheed Martin Corporation Mode suppression resonator

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3010047A (en) * 1959-03-09 1961-11-21 Hughes Aircraft Co Traveling-wave tube
US3153767A (en) * 1960-06-13 1964-10-20 Robert L Kyhl Iris-loaded slow wave guide for microwave linear electron accelerator having irises differently oriented to suppress unwanted modes
US3205398A (en) * 1960-04-18 1965-09-07 Matthew A Allen Long-slot coupled wave propagating circuit
US3324340A (en) * 1963-10-08 1967-06-06 Csf Linear travelling wave particle accelerator having spaced shaped apertures

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3010047A (en) * 1959-03-09 1961-11-21 Hughes Aircraft Co Traveling-wave tube
US3205398A (en) * 1960-04-18 1965-09-07 Matthew A Allen Long-slot coupled wave propagating circuit
US3153767A (en) * 1960-06-13 1964-10-20 Robert L Kyhl Iris-loaded slow wave guide for microwave linear electron accelerator having irises differently oriented to suppress unwanted modes
US3324340A (en) * 1963-10-08 1967-06-06 Csf Linear travelling wave particle accelerator having spaced shaped apertures

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150171502A1 (en) * 2008-08-12 2015-06-18 Lockheed Martin Corporation Mode suppression resonator
US9768486B2 (en) * 2008-08-12 2017-09-19 Lockheed Martin Corporation Mode suppression resonator

Also Published As

Publication number Publication date
GB1361833A (en) 1974-07-30
IL37440A (en) 1974-01-14
IL37440A0 (en) 1971-11-29
FR2107128A5 (fr) 1972-05-05
DE2142869A1 (de) 1972-03-16
CA939812A (en) 1974-01-08

Similar Documents

Publication Publication Date Title
US3668459A (en) Coupled cavity slow wave circuit and tube using same
US2320860A (en) Electron discharge apparatus
US3558967A (en) Linear beam tube with plural cathode beamlets providing a convergent electron stream
USRE25329E (en) Periodically focused traveling wave tube
US3221204A (en) Traveling-wave tube with trap means for preventing oscillation at unwanted frequencies
GB1562162A (en) Variable energy highly efficient linear accelerator
US4395655A (en) High power gyrotron (OSC) or gyrotron type amplifier using light weight focusing for millimeter wave tubes
US8242696B1 (en) Vacuum electronic device
US3278791A (en) Electron discharge device having a plurality of emissive surfaces
CA1135860A (fr) Circuit a ondes lentes pour tubes a ondes progressives
US3365607A (en) Electron discharge device
US3628084A (en) Coupled cavity slow wave circuit and tube using same
US3684913A (en) Coupled cavity slow wave circuit for microwave tubes
US3205398A (en) Long-slot coupled wave propagating circuit
US3576460A (en) Impedance match for periodic microwave circuits and tubes using same
US3611166A (en) Accelerator for relativistic electrons
US3594606A (en) Velocity modulation tube employing cascaded harmonic prebunching
US3454817A (en) Coupled cavity high-frequency electron discharge device with means for reducing the q at undesired regions without overloading the q in the operating regions
US3846664A (en) Coupled cavity travelling wave tubes
US3305749A (en) Electron discharge device having plural electron beams, slow wave structures, and r.f. signals, each signal interacting with a plurality of beams
US3466576A (en) Impedance matched periodic slow wave structure
US3594605A (en) Mode suppression means for a clover-leaf slow wave circuit
US3248597A (en) Multiple-beam klystron apparatus with periodic alternate capacitance loaded waveguide
US3289032A (en) Microwave hybrid tube apparatus
US3292033A (en) Ultra-high-frequency backward wave oscillator-klystron type amplifier tube