US3708764A - Travelling wave tubes - Google Patents

Travelling wave tubes Download PDF

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Publication number
US3708764A
US3708764A US00108778A US3708764DA US3708764A US 3708764 A US3708764 A US 3708764A US 00108778 A US00108778 A US 00108778A US 3708764D A US3708764D A US 3708764DA US 3708764 A US3708764 A US 3708764A
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Prior art keywords
cathode
high frequency
ultra
delay line
tube
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Expired - Lifetime
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US00108778A
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English (en)
Inventor
P Guenard
B Epsztein
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Thales SA
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Thomson CSF SA
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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
    • H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy
    • H01J23/54—Filtering devices preventing unwanted frequencies or modes to be coupled to, or out of, the interaction circuit; Prevention of high frequency leakage in the environment

Definitions

  • an M type tube is a travelling wave tube (direct or backward) comprising, in addition to the elements present in other travelling wave tubes, an electrode, known as sole, and means for providing a magnetic field, perpendicular to the electric field prevailing between the delay line of the tube and this sole and to the direction of propagation of the wave and of the electron beam, in the space bounded by the delay line and the sole.
  • these tubes generally comprise microwave input and output, connected to the delay line at its ends.
  • travelling wave amplifiers or M type TWT
  • phase locked oscillators such as the well-known Carpitron (Registered trade mark) operating on backward mode.
  • the density modulation above referred to has nothing in common with the usual modulation.
  • triodes of the known art operating at a wave length outside the microwave range, that is to say higher than 40 to cm, among the devices, provided with periodic delay circuits to pick up the energy from the electrons of the beam.
  • the tubes with which the present invention is concerned substantially differ from all the tubes of the prior art, and even from those involving periodic structures.
  • the diocotron effect occurs in the remaining space of the electron gun extending between the grid and the beginning of the periodic delay structure of the tube. In this zone, the Diocotron effect appears in the beam, as already explained, achieving an amplification of the injected signal together with the noise signal. It is to be noted that there is no change, during this amplification, in the signal-to-noise ratio. The only and other outstanding result is the reduction in the input power needed to operate the tube at the rated output characteristics, this reduction due to the Diocotron gain.
  • an M- type'microwave tube including a cathode, means for modulating the electron beam at the output of said cathode, and ultra-high frequency input means for feeding modulating ultra-high frequency energy to said modulating means.
  • FIGS. 1 and 2 schematically illustrate, in partial section, two embodiments of a microwave tube in accordance with the invention, given in the case of an amplifier.
  • FIG. 1 relates to a linear M type tube. It comprises an evacuated enclosure defined by an envelope 30 an indirectly heated cathode 2 with a filament 1, a modulating grid 3 a delay line 5 for example of the vane type, a sole 4 a beam focussing electrode 6 and an electrode 7 for magnetically screening the, beam.
  • a magnetic field is applied on the tube perpendicularly to the figure plane.
  • This tube differs from a conventional M type travelling wave amplifier tube equipped with a conventional current control electrode, in terms of the following features the input of the device for density modulating the beam (schematically illustrated by a wire in FIG. 1), is a microwave input the delay line terminates, at the electron gun end, in a matched load, in order to avoid any internal reflections, but has no localized absorbing attenuation or sever.
  • the matched load 14 which is here shown outside the envelope 30 can equally well be located inside the evacuated enclosure. It may be of any conventional kind, a carbon charge, a water wedge, or, if it is inside the tube, an absorbing deposit at the end of the delay line which is located near the electron gun.
  • the connection between the delay line and the load should be made extremely carefully in order to prevent any reflection phenomena; all the line has a uniform structure up to the high frequency output.
  • the operation of the tube will be explained by means of FIG. 1 in which it is simply the tube input connection arrangement which has been shown, the other supply arrangements being conventional.
  • the base 4 carries a negative potential with respect to the cathode, while the delay line is earthed along with the positive terminal of the high-voltage source, the negative terminal of the source being taken to the cathode.
  • the grid 3 is at a potential equal to or close to that of the cathode, thanks to an auxiliary voltage supply 11.
  • a choke can be arranged in the circuit.
  • the microwave signal to the amplifier is produced by a microwave source, for example an oscillator 9.
  • the signal is applied to the grid 3 by means of a capacitor 8 which isolates the oscillator 9 from the high voltage applied to the grid 3.
  • the microwave input signal the amplitude of which exceeds largely that of the parasitic signals or noise components present in the beam, modulates said beam in density.
  • this microwave signal experiences very substantial gain along the beam in the space defined between the grid and the delay. line, this amplification, in accordance with the hypothesis set out hereinbefore being due to the Diocotron effect.
  • the beam subsequently induces its power into the delay line which supplies it to the useful load 16 in the same way as in a conventional M type travelling wave tube.
  • a collector l7 finally picks up the beam.
  • the improvement in accordance with the invention besides its features of gain and signal-to-noise ratio improvements has other advantages, namely suppression of localized attenuation or sever usually needed in conventional M-type amplifier tubes, with consequently a substantial reduction in the length of the delay line by the length of the localized attenuation arrangement, and by the necessary length of the line section preceding this attenuation, and finally a substantial reduction of the overall size of the tube excellent decoupling between tube low level input and power output.
  • the device for density modulating the beam at the cathode comprises 'a coaxial section 21 into which the high frequency signal is injected. Its end forms a T which is terminated on the one hand in a cathode 2 the latter being carried by the internal conductor 20 of the coaxial section, and on the other hand in a grid 27 which is carried by the external conductor 22 of the coaxial section, a space separating grid and cathode the length of the coaxial section is selected so that the microwave signal modulating the beam has a maximum amplitude at the cathode U.I-I.F. traps 23 of M4 type 0 being the wavelength of the high frequency signal modulating the beam), isolate the high voltage on cathode 2 and grid 27, from the rest of the coaxial section.
  • the circuit in accordance with the invention is applicable to an oscillator circuit utilizing a locked M type tube of the backward-wave kind.
  • the tube differs from a Carpitron equipped with a device for low-frequency modulation of the beam at the cathode, in that the input of the modulation device will be a microwave input, and in that at the collector end, the delay line is terminated not by the usual absorbing zone of limited attenuation of a Carpitron, which eliminates only partially the reflections at the end of the line, but by a matched load.
  • a traveling wave tube of the M-type including: a delay line, an electrode substantially parallel thereto and raised to a potential which is negative relative to the potential of the delay line whereby an electric field is provided between the delay line and the electrode, means for providing within said tube a magnetic field normal to the electric field, and a cathode for propagating an electron beam normal to both of the fields, said tube further comprising: means for modulating the electron beam being located at the immediate vicinity of the cathode and being energized both by a negative biasing potential and ultra-high frequency energy which is the energy to be propagated along the delay line.
  • the traveling wave tube of the M-type according to claim 2 comprising: further ultra-high frequency input means for feeding ultra-high frequency energy to the delay line.
  • the traveling wave tube of the M-type according to claim 1 comprising: means for collecting ultra-high frequency energy at an end of said delay line which is remote from said cathode, and matched absorbing means coupled to the other one of said ends.
  • the traveling wave tube of the M-type according to claim 1, comprising: means for collecting ultra-high frequency energy at an end, of said delay line. which is near said cathode, and matched absorbing means coupled to the other one of said ends.
  • said means for modulating the electron beam at the cathode comprises a coaxial guide, one end thereof terminated by the cathode, supported by an internal conductor of the coaxial section separated from the cathode by a selected space terminating the other end thereof; and a grid supported by an external conductor of the coaxial section.

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  • Microwave Amplifiers (AREA)
  • Amplifiers (AREA)
  • Particle Accelerators (AREA)
US00108778A 1970-01-26 1971-01-22 Travelling wave tubes Expired - Lifetime US3708764A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7002643A FR2076723A5 (enrdf_load_stackoverflow) 1970-01-26 1970-01-26

Publications (1)

Publication Number Publication Date
US3708764A true US3708764A (en) 1973-01-02

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US00108778A Expired - Lifetime US3708764A (en) 1970-01-26 1971-01-22 Travelling wave tubes

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US (1) US3708764A (enrdf_load_stackoverflow)
DE (1) DE2103608C2 (enrdf_load_stackoverflow)
FR (1) FR2076723A5 (enrdf_load_stackoverflow)
GB (1) GB1344385A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4253068A (en) * 1979-05-21 1981-02-24 Barnett Larry R Cyclotron maser using a spatially nonlinear electrostatic field
RU2187880C1 (ru) * 2001-04-04 2002-08-20 Государственное унитарное предприятие Государственный Рязанский приборный завод - дочернее предприятие государственного унитарного предприятия Военно-промышленного комплекса "МАПО" Передатчик свч

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9322934D0 (en) * 1993-11-08 1994-01-26 Eev Ltd Linear electron beam tube arrangements

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2702370A (en) * 1953-03-18 1955-02-15 Csf Pulse-modulated traveling wave tube with crossed electric and magnetic fields
US2704350A (en) * 1953-03-18 1955-03-15 Csf Traveling wave tubes which have intersecting electric and magnetic fields and are pulse modulated
US2888597A (en) * 1952-12-13 1959-05-26 Csf Travelling wave oscillator tubes
US2922918A (en) * 1955-01-17 1960-01-26 Csf Traveling wave oscillators
US3008093A (en) * 1957-01-24 1961-11-07 Csf M-type backward wave oscillator
US3072864A (en) * 1958-09-04 1963-01-08 Csf Frequency modulation systems
US3114886A (en) * 1960-11-01 1963-12-17 Sperry Rand Corp Pulse regulating system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2237878A (en) * 1939-02-02 1941-04-08 Rca Corp Electron discharge device
GB582526A (en) * 1943-01-22 1946-11-20 Sperry Gyroscope Co Inc Improvements in or relating to ultra high frequency electron discharge devices

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2888597A (en) * 1952-12-13 1959-05-26 Csf Travelling wave oscillator tubes
US2702370A (en) * 1953-03-18 1955-02-15 Csf Pulse-modulated traveling wave tube with crossed electric and magnetic fields
US2704350A (en) * 1953-03-18 1955-03-15 Csf Traveling wave tubes which have intersecting electric and magnetic fields and are pulse modulated
US2922918A (en) * 1955-01-17 1960-01-26 Csf Traveling wave oscillators
US3008093A (en) * 1957-01-24 1961-11-07 Csf M-type backward wave oscillator
US3072864A (en) * 1958-09-04 1963-01-08 Csf Frequency modulation systems
US3114886A (en) * 1960-11-01 1963-12-17 Sperry Rand Corp Pulse regulating system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4253068A (en) * 1979-05-21 1981-02-24 Barnett Larry R Cyclotron maser using a spatially nonlinear electrostatic field
RU2187880C1 (ru) * 2001-04-04 2002-08-20 Государственное унитарное предприятие Государственный Рязанский приборный завод - дочернее предприятие государственного унитарного предприятия Военно-промышленного комплекса "МАПО" Передатчик свч

Also Published As

Publication number Publication date
DE2103608A1 (de) 1971-08-05
FR2076723A5 (enrdf_load_stackoverflow) 1971-10-15
DE2103608C2 (de) 1982-09-16
GB1344385A (en) 1974-01-23

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