US3529204A - Electron beam discharge tube having a retarding structure with a tuning device - Google Patents

Electron beam discharge tube having a retarding structure with a tuning device Download PDF

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Publication number
US3529204A
US3529204A US721487A US3529204DA US3529204A US 3529204 A US3529204 A US 3529204A US 721487 A US721487 A US 721487A US 3529204D A US3529204D A US 3529204DA US 3529204 A US3529204 A US 3529204A
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United States
Prior art keywords
tuning
electron beam
retarding structure
tube
cavity resonators
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Expired - Lifetime
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US721487A
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English (en)
Inventor
Bernardus Bastiaan Van Iperen
Wilhelmus Kuypers
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US Philips Corp
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US Philips Corp
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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
    • H01J23/16—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
    • H01J23/207—Tuning of single resonator
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
    • H01J25/10—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator
    • H01J25/12—Klystrons, i.e. tubes having two or more resonators, without reflection of the electron stream, and in which the stream is modulated mainly by velocity in the zone of the input resonator with pencil-like electron stream in the axis of the resonators

Definitions

  • An electron beam tube having a retarding structure including at least three substantially identical cavity resonators arranged successively in the direction of length of the tube and coupled electromagnetically, the retarding structure also including a device for tuning the retarding structure which is directly coupled to at least one cavity resonator which is substantially at the center of the series of cavity resonators.
  • This invention relates to an electron beam tube having a retarding structure comprising a series of at least three substantially identical cavity resonators succeeding in the direction of length of the tube and firmly coupled electromagnetically, leaving a substantially rectilinear longitudinal passage for the electron beam, which retarding structure includes a tuning device intended for tuning the retarding structure as a whole and directly coupled to a fraction of the total number of cavity resonators.
  • An electron beam tube having a retarding structure comprising a series of electromagnetically-coupled cavity resonators leaving a rectilinear passage for the electron beam is used for amplifying or generating microwaves.
  • Such tubes preferably include means of changing the tuning of the retarding structure, in order to meet with wide tolerances and permit a certain frequency range to be governed. Means such as are sometimes present in tubes intended for meter waves and decimeter waves, which permit each cavity resonator to be tuned individually, become impracticable in tubes intended for the microwave spectrum.
  • the last-mentioned tubes can, however, include a practical means of tuning the structure as a whole.
  • Such tubes having a large number of substantially identical cavity resonators succeeding in the direction of length of the tube and firmly coupled electromagnetically are known in which a tuning device for tuning the structure as a whole is directly coupled to one of the end cavity resonators of the series.
  • a tuning device for tuning the structure as a whole is directly coupled to one of the end cavity resonators of the series.
  • the energy transmission between the electron beam and the electromagnetic field in the retarding structure is a maximum.
  • the resulting variations in the field will cause a decrease in the energy transmission between the electron beam and the electromagnetic field.
  • This frequency interval may be referred to as the tuning range.
  • the disadvantage of such a tube is that the energy transmission between the electron beam and the electromagnetic wave varies comparatively rapidly as a function of frequency, in other words the retarding structure has a comparatively small tuning range.
  • An object of the invention is to provide an electron beam tube having a wider tuning range.
  • an electron beam tube having a retarding structure comprising a series of at least three substantially identical cavity resonators succeeding in the direction of length of the tube and firmly coupled electromagnetically, leaving a substantially rectilinear passage for the electron beam,
  • which retarding structure includes a tuning device intended for tuning the retarding structure as a whole and directly coupled to a fraction of the total number of cavity resonators, said tuning device is directly coupled to at least one cavity resonator which is located substantially at the center of the series of cavity resonators.
  • the energy transmission between the electron beam and the standing electromagnetic waves in the retarding structure in this tube will take place substantially as a result of the interaction between the beam and one of the spatial harmonics of the electric field in the z-direction, for example the m harmonic with a phase constant 13
  • the argument B z of this m harmonic per cavity resonator will increase in the z-direction by a constant value ,fi L if L is the length of a cavity resonator.
  • the m harmonic of the electric field in the z-direction which occurs after a change of tuning will have an argument E z which increases per cavity resonator in the z-direction by a constant amount TJ L which differs from ,B L.
  • the change of tuning will cause an average variation in argument of approximately /2 (E -B )L. If the cavity resonators adjacent the end cavity resonators are neither coupled directly to the tuning device, the average variation therein will be -fl )L. Passing from a cavity resonator situated at the end of the retarding structure towards the nearest cavity resonator to which the tuning device is directly coupled, the variation of the argument in succeeding cavity resonators steadily increases by (F -B )L.
  • B )L is always small so that the field variation in succeeding cavity resonators, passing from a cavity resonator situated at the end of the retarding structure towards the (nearest) cavity resonator to which the tuning device is directly coupled, steadily increases. Consequently, greater field variations occur as the largest number of cavity resonators between one end of the structure and the tuning device is larger, this largest number being minimum if the tuning device is directly coupled to the retarding structure exactly at the center thereof.
  • the tube according to the invention exhibits a smaller deformation of field, and hence a smaller variation in transmitted energy, than a tube in which a cavity resonator located at the end of a similar retarding structure is directly coupled to the tuning device. With unchanged requirements with respect to the transmitted energy, the tuning of a tube according to the invention can thus be changed over a larger frequency band, in other words: this tube has a wider tuning range.
  • the tuning device preferably comprises a wavepipe section transversed to the path of the electron beam and divided by a vacuum window into two parts one of which is directly coupled through a coupling aperture to the cavity resonator(s) situated at the center of the series of cavity resonators and the others of which includes an adjustable tuning member and has at least one aperture so that the tuning device can also be used for coupling to an external Wavepipe circuit.
  • FIGS. 1, 2, 3, 4 and 5 serve to clarify the occurence of and improvement in the tuning range of a retarding structure comprising succeeding cavity resonators by coupling the tuning device directly to a cavity resonator at the center of the retarding structure, where FIG. 1 schematically shows a known retarding structure comprising a plurality of succeeding identical cavity resonators which cannot be tuned;
  • FIG. 2 schematically shows a known device comprising the retarding structure of FIG. 1 in which one end cavity resonator is provided with a tuning derive;
  • FIG. 3 schematically shows a device comprising the retarding structure of FIG. 1 in which, in accordance with the invention, the central cavity resonator is provided with a tuning device;
  • FIG. 4 is a graph showing a component of the axial electric field at the dots indicated in FIGS. 1, 2 and 3;
  • FIG. 5 is a graph showing the relationship between the frequency and the phase constants of the waves occurring in the retarding structure of FIG. 1.
  • FIGS. 6, 7 and 8 show to scale one embodiment of a section of the electron beam tube according to the invention, where FIG. 6 ShOWs a longitudinal section of the electron beam tube;
  • FIG. 7 is a sectional view of the electron beam tube, taken on the line VIIVII of FIG. 6, and
  • FIG. 8 is a sectional view taken on the line VIIIVIII of FIG. 7.
  • a retarding structure 1 comprises a plurality of identical cavity resonators 2 of the reentrant type having nozzles 3 which determine a substantially rectilinear passage for the electron beam through apertures 4.
  • the path of the electron beam extends along the longitudinal axis of the structure, which is indicated as the z-axis.
  • the cavity resonators 2 have coupling slots 5 for their electromagnetic coupling.
  • Dots 6 located at the centers of the cavity resonators 2 are indicated on the z-axis.
  • the axial resonant electric field in the retarding structure 1 may be written as the sum of. an infinite number of spatial harmonics having phase constants fi which, on the ground of their periodicity, satisfy the relationship:
  • phase constant ,8 of the fundamental wave satisfies the condition for resonance where k is an integer and N is the total number of cavity resonators.
  • the retarding structure 1 of FIG. 1 is provided with a piston 7 in FIG. 2 and with a piston 8 in FIG. 3.
  • this piston By means of this piston the tuning of the sturcture may be changed.
  • the tuning of the structure 1 is changed by means of an effective reduction in length AL, then a field is produced which satisfies the specified relationship (A) between the phase constants of the spatial harmonics and the said condition for resonance (B), but with the understanding that NL in these relationships has been replaced by NLAL.
  • the field of the m harmonic at the dots between the end of an end cavity resonator which is not directly coupled to the tuning device then varies by a factor which harmonically depends upon the distance from this end and has a phase constant A,8. From the limiting conditions it follows that said factor must have a maximum at this end.
  • the vertical coordinate indicates the value of the electric field E in the z-direction and the horizontal axis is the z-axis.
  • the dots located on the line I indicate the amplitudes E of the field at the dots 6 of the structure 1 of FIG. 1 the tuning of which has not been changed. These values of the field are asumed simultaneously and vary harmonically in time.
  • the dots located on the full line II indicate the amplitudes of the field at the dots 6 of the structure 1 the tuning of which has been changed by an effective reduction in length AL by means of a device as shown in FIG. 2.
  • both devices are to fulfill the condition that, upon changing the tuning, the amplitudes of the field strength at the dots 6 are allowed to decrease not more than up to a fraction fE of E, then the said harmonic factor at the dots 6 must be greater than 1, which may be written as follows:
  • the curve of FIG. 5 shows the relationship between at and ⁇ 5 for a retarding structure as shown in FIG. 1.
  • the curve is periodic with a period 21r/L.
  • AB phase constant variations
  • Aw variations
  • the said maximum variations (AM and (Am) are as shown in FIG. 5, such small variations, so that the maximum variation (Aw) corresponding to (Am is more than thirteensevenths times as great as the permissible variation (Aw) corresponding to (AM
  • FIG. 6 shows, inside a tube body 11, a retarding structure comprising six identical re-entrant cavity resonators 12 bounded by sleeves 13 and discs 14.
  • the nozzles 15 determine a rectilinear passage for the electron beam, the path of which is indicated by 16.
  • the cavity resonator discs 14 have coupling slots 17.
  • the end cavity resonators are closed by covers 18 and 20, respectively, having apertures 19 and 21, respectively, to allow passage of the electron beam.
  • the central cavity resonators are coupled through an aperture 22 to a wavepipe section 23 having a window 25 and an aperture 27 and provided with a threaded ring 28 for coupling to an external wavepipe circuit.
  • a pin 29 for changing the tuning extends into section 23.
  • FIG. 7 shows that each cavity resonator disc 14 exhibits three coupling slots 17 at positions relatively rotated by 120".
  • the figure also shows that the pin 29 is set in a holder 31 which is pushed against a tuning screw 33 by a spring 32.
  • the tuning screw 33 is screwed into a cover 34 of a housing 35 which is secured to the tube body 11.
  • the tuning range of the retarding structure in the embodiment above described is approximately four times as large as that in a device having a similar retarding structure in which the tuning device is coupled to one of the end cavity resonators.
  • An embodiment as above described which can be constructed in a comparatively simple manner, may be used, for example, as a self-oscillating modulator in a tube for generating sub-millimeter waves.
  • An electron beam tube having a retarding structure comprising a series of at least three substantially identical cavity resonators succeeding in the direction of length of the tube, means firmly coupling said cavity resonators electromagnetically, leaving a substantially rectilinear longitudinal passage for an electron beam, and a tuning device for tuning the retarding structure as a whole and directly coupled to a fraction of the total number of cavity resonators, said tuning device being directly coupled to at least one cavity resonator located substantially at the center of the series of cavity resonators.
  • tuning device comprises a wavepipe section transversed to the path of the electron beam and divided by a vacuum window into two parts one of which is directly coupled through a coupling aperture to the cavity resonators of the said fratcion and the other of which includes an adjustable tuning member and has at least one aperture for coupling to an external wavepipe circuit.

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US721487A 1967-05-04 1968-04-15 Electron beam discharge tube having a retarding structure with a tuning device Expired - Lifetime US3529204A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6706280A NL6706280A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1967-05-04 1967-05-04

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US (1) US3529204A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE1766134A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
FR (1) FR1570076A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
GB (1) GB1171876A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
NL (1) NL6706280A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2449331A1 (fr) * 1979-02-13 1980-09-12 Sits Soc It Telecom Siemens Dispositif pour l'accord de tubes a micro-ondes
US5469023A (en) * 1994-01-21 1995-11-21 Litton Systems, Inc. Capacitive stub for enhancing efficiency and bandwidth in a klystron
US6259207B1 (en) 1998-07-27 2001-07-10 Litton Systems, Inc. Waveguide series resonant cavity for enhancing efficiency and bandwidth in a klystron

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3322997A (en) * 1963-06-14 1967-05-30 Varian Associates Permanent magnet focused klystron
US3360679A (en) * 1964-02-21 1967-12-26 Varian Associates Electron discharge device having lossy resonant elements disposed within the electromagnetic field pattern of the slow-wave circuit
US3441783A (en) * 1964-12-07 1969-04-29 English Electric Valve Co Ltd Travelling wave amplifier tubes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3322997A (en) * 1963-06-14 1967-05-30 Varian Associates Permanent magnet focused klystron
US3360679A (en) * 1964-02-21 1967-12-26 Varian Associates Electron discharge device having lossy resonant elements disposed within the electromagnetic field pattern of the slow-wave circuit
US3441783A (en) * 1964-12-07 1969-04-29 English Electric Valve Co Ltd Travelling wave amplifier tubes

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2449331A1 (fr) * 1979-02-13 1980-09-12 Sits Soc It Telecom Siemens Dispositif pour l'accord de tubes a micro-ondes
US5469023A (en) * 1994-01-21 1995-11-21 Litton Systems, Inc. Capacitive stub for enhancing efficiency and bandwidth in a klystron
US6259207B1 (en) 1998-07-27 2001-07-10 Litton Systems, Inc. Waveguide series resonant cavity for enhancing efficiency and bandwidth in a klystron

Also Published As

Publication number Publication date
NL6706280A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1968-11-05
FR1570076A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1969-06-06
DE1766134A1 (de) 1971-06-03
GB1171876A (en) 1969-11-26

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