US2623129A - Thermionic tube for amplification of ultrashort electric waves - Google Patents

Thermionic tube for amplification of ultrashort electric waves Download PDF

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Publication number
US2623129A
US2623129A US95188A US9518849A US2623129A US 2623129 A US2623129 A US 2623129A US 95188 A US95188 A US 95188A US 9518849 A US9518849 A US 9518849A US 2623129 A US2623129 A US 2623129A
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electrons
cathode
tube
wave
helix
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Expired - Lifetime
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US95188A
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English (en)
Inventor
Lerbs Alfred
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Thales SA
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CSF Compagnie Generale de Telegraphie sans Fil SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/34—Travelling-wave tubes; Tubes in which a travelling wave is simulated at spaced gaps
    • H01J25/36—Tubes in which an electron stream interacts with a wave travelling along a delay line or equivalent sequence of impedance elements, and without magnet system producing an H-field crossing the E-field

Definitions

  • My invention relates to anew type of: tubes called progressive-wave tubes which, although they are more particularly used as amplifiers, can also be used for producing and receiving ultra-short electric waves.
  • tubes of this type comprise an input terminal E and an output terminal S between which extends a delay line through which a progressive-wave travels at a phase velocity u which is parallel to the delay line and the direction of which is the same as that of the phase of the progressive wave, is located throughout its travel from E to S in the high-frequency field produced by the progressive wave.
  • the velocity in of the electrons it is necessary for the velocity in of the electrons to be equal to the phase velocity Up.
  • the delay line is formed by a wire wound in the shape of a cylindrical helix H, in order to. decrease the phase velocity u it would be necessary to reduce the distance a between the convolutions, or increase their diameter d (see Fig. 1 in which the arrow shows the direction of the electron beam and of the phase of the progressive wave, Q is the cathode, E and S are respectively the input and the output terminals of the delay line).
  • Fig. 1 in which the arrow shows the direction of the electron beam and of the phase of the progressive wave, Q is the cathode, E and S are respectively the input and the output terminals of the delay line).
  • these two means produce a decrease in the necessary energy exchange between the electron beam and the progressive wave, because a decrease in the distance a causes the field of the progressive wave to shift in the direction of the contraction of the helix and an increase in the diameter d increases the distance between the axis of the elec' tron beam and the delay line.
  • My invention enables the said drawbaclrs to be obviated, since therein the voltage of the anode is independent of the phase veiocity. No o n ne h r e be taken of t at e oc ty in choosing the distance between the convolu- The electron beam, the path of tions, so that the exchange of energy between the field of the progressivewave and the electrons can be considerably increased. Furthermore, it procures the advantage of not having to use special electron optical devices and of enabling without difficulty considerable currents to be made to flow through the tube according to the invention.
  • My invention has for its object a tube which procures such advantages and which comprises an emitting cathode and an anode constructed in the shape of a delay line provided with an input terminal and an output terminal, a wave being adapted to travel progressively through said line, and an electric field which extends between the, cathode and the anode and is directed towards the anode.
  • the emitting cathode and the anode are arranged coaxially so that the axis of the cathode extends in the direction of propagation of the wave in the anode, said anode and said cathode both being preferably of linear shape.
  • the essential difference between the new tube and those heretofore used consists in the fact that there need not be a movement of electrons in the direction oi the phase of the progressive wave, but that there is a periodic reciprocating movement of the electrons in a direction at right angles to that of said phase.
  • the exchange of energy between the electrons and the progressive wave is effected by means of the transverse component of the high-freduencyfield.
  • Fig. 2 shows the instantaneous distribution of the highfrequency field produced by the progressive wave of said transverse component as it propagates along the cylindrical helix H.
  • the line a- -a1 indicates the position of the longitudinal component and the direction of the movement of the electrons in the tubes heretofore used.
  • transverse component of the field use is made of the transverse component of the field, said transverse component being at right angles to said line and producing a periodic reciprocating movement of the electrons parallel to b-b1.
  • the necessary energy for the movement of the electrons is supplied by a source of direct current. If suitable means are chosen so that the largest possible number of electrons can transfer the energy obtained from the source of direct current to the high frequency field and that on the. other hand a mall number o e ec receive highfrequency energy, an amplification of the progressive wave takes place.
  • Fig. 1 shows a diagrammatic arrangement of th known progressive-wave tube.
  • Fig. 2 shows the distribution of the field.
  • Figs. 3 and 31 show the diagrammatic arrangement and Fig. 3a the practical construction of the tube according to the invention.
  • Fig. 4 shows the distribution of the field in such a tube.
  • Fig. 5 is intended to enable a known magnetron to be compared with Fig. 32).
  • Fig. 6 shows a distribution of the field.
  • Figs. '7, 8, 9, 10, 11 and 12 show diagrammatically modifications of electrode and supply arrangements.
  • a tube according to the invention is shown diagrammatically in longitudinal section and in transverse section in Fig. 3 and in a more complete manner in Fig. 3a.
  • E and S denote the input terminal and the output terminal of the delay line which, in this embodiment, is of the shape of a cylindrical helix.
  • the cathode C heated by the auxiliary battery Ch.
  • the invention also provides, according to a modification, a constant magnetic field B, the direction of which is shown by the arrow B and is parallel to the axis.
  • Fig. 3 shows a more complete view of such a tube, wherein the same reference numerals denote the same elements.
  • the input E and the output S of the delay line are effected by means of coaxial cables L1 and 1.2 through the vacuum-tight bulb V of the tube.
  • B1 and B2 show schematically the pole-pieces of an electromagnet adapted to produce the magnetic field B parallel to the cathode.
  • U1 and U2 denote the leading-in wires of the cathode C which are intended to be connected to the terminals of a cathode heating battery, the helix H and the cathode C being connected to a source Vd of direct current voltage according to Fig. 3 and not shown in Fig. 3a.
  • Fig. 4 shows the instantaneous distribution of the high-frequency field of such a tube.
  • the lower curve shows the corersponding instantaneous values of the transverse component along the helix.
  • this diagram moves from E towards S, whereas the movement of the electrons takes place in the same transverse section in which they were emitted by the cathode.
  • the transverse component of the high-frequency field which acts on the electrons, therefore varies in cadence with the high-frequency. Consequently, during their pendular movement between H and C, the electrons are subjected to almost the same conditions as in a magnetron with a non-slotted anode, which is shown diagrammatically in Fig. 5.
  • A is the anode, in the axis of which the cathode C is located; B denotes the magnetic field; I, 2, 3 are the trajectories of the electrons.
  • the oscillating circuit represented by the capacitors C1, C2 and the inductance L is located between C and A; in the. radial direction.
  • A is the length of the progressive wave in centimetres, measured in air
  • K is a coefilcient of about 12,000, which may vary within certain limits according to the distribution of the field in the discharge space.
  • the magnetic field is therefore determined by the wavelength, while the anode voltage U... which exists between H and C can be approximately calculated if the value of B and the radii of the transverse sections of H and of C are known:
  • Fig. 6 shows such a distribution of the field.
  • the dotted lines represent the lines of force.
  • the voltage is so chosen that the helix can be considered as an equipotential electrode, the distribution of the field remains constant in the direction of the axis and corresponds to Fig. 7.
  • fields can be obtained of an intermediate shape between the shapes shown in Figs. 6 and 7.
  • the electrode P can be used to act on the electronic mechanism and to adjust same.
  • the cathode C and the outer cylinder P may also be permuted as shown in Fig. 8, so that use is made of the portion of the high-frequency field located outside the helix.
  • Such an ar rangement should be considered in particular if there is a considerable dissipation of energy in the tube and if an inadmissible heating of the cathode due to the bombardment of the electrons (retroactive heating) occurs.
  • the possibility can be readily obtained of making only a portion of the cathode operative for effecting the emission, for
  • the progressive-wave tube with a magnetic field hereinbefore described is only a non-limitative example of the embodiment of the idea of the invention. It is also possible to consider the use of electronic mechanisms in which a magnetic field is not necessary for obtaining an oscillatory movement of the electrons. Such a pendular movement can be obtained, for example in the device of Fig. '7, without needing a magnetic field, but by supplying the electrode P with a voltage which is negative with respect to the cathode, while the helix is supplied with a positive voltage. This system is shown in Fig. 10 which only differs from Fig. 7 by a permutation of the connections of the electrodes C, P, H.
  • the electrons are thus reflected by the negative electrode and oscillate between same and the cathode until they are collected by the helix 1-1.
  • a special grid A Fig. 11
  • the electrode P can be used in a similar manner to that hereinbefore described for the progressive- Wave tube with a magnetic field, but in this case said electrode would have to be supplied with. a high negative voltage.
  • the delay line of the shape of a single helix it is not essential to make the delay line of the shape of a single helix, its being possible, for example, for said line to be formed by a suitably chosen bifilary line. Similarly, it is not essential to choose a radially symmetrical shape for the electrode system.
  • the electrons can only transfer their energy to the A. C. field of the progressive wave, for low A. C. voltages, in small quantities and consequently it is necessary for there to be a large number of oscillations for each electron that transfers energy. It is therefore advisable to arrange for the period of oscillation of the electrons that transfer energy to be constant, independen ly of the amplitude, and for the electrons which are not of the requisite phase (i. e. those which absorb the energy from the A. C. field) to be converted into electrons of the correct phase.
  • the tubes are symmetrical is important for the practical Working. As a result thereof an amplification can take place both for a progressive wave which is propagated from E towards S and for a wave which is propagated in the opposite direction, from S towards E.
  • the input and the output can therefore be permuted. This may, if necessary, facilitate self-oscillation if, owing to the insuificient matching of the output apparatus at the output of the delay line, part of the energy is reflected and returns from S to E.
  • the tubes may be rendered asymmetrical by substantially reducing the undesirable amplification in the direction S-E with respect to the desired amplification in the direction E-S, as a result of which the input and the output can no longer be permuted.
  • a certain degree of asymmetry in the case of the tube with a magnetic field hereinbefore described is moreover already produced by the fact (not hereinbefore mentioned) that the electrons efiect a movement about the axis of the system of the tube, parallel to a convolution of the helix (see Figs. 3 and 9). This movement therefore takes place in the same direction or in the opposite direction to the direction of propagation of the progressive wave along the wire of the helix.
  • the said movement takes place in the same direction as the propagation of said wave from E to S, it is in the opposite direction to the direction of propagation from E to S of the reflected wave. Consequently, diiferent conditions are produced for the oscillation frequency of the electrons for the incident Wave and for the reflected wave. If this frequency is adjusted in the most advantageous manner for the progressive wave travelling from E to S, the conditions for the wave travelling in the opposite direction are less favorable.
  • the tube is thus asymmetrical.
  • the tubes have to be rendered asymmetrical by artificial means.
  • this result can be obtained by continuously or gradually varying the operating conditions along the tube, from E to S, in such a manner as to make them very advantageous near E for low A. C. voltages and for high voltages near S.
  • This can be effected in practice by using various methods. For example, the distance between the convolutions may be made comparatively great near E and be successively decreased towards S. In this case, an active exchange of energy with the electrons is only obtained in the presence of fairly high A. C. voltages, for a small spacing between the convolutions.
  • a composite refleeting electrode comprising a plurality of electrodes which are aligned between E and S and operate at difierent reflecting voltages.
  • the desired asymmetries can be obtained by gradually or continuously varying the distance between or the dimensions of the electrodes.
  • An ultra-short wave amplifying tube comprising a delay line having an input end and an output end, means coupled with said input end for feeding an electromagnetic wave into the delay line, means coupled with the output end for 8 removing amplified energy from the delay line, an emissive cathode extending coaxially with respect to the delay line, a direct potential source connected to the extremities of said cathode for passing a heating current therethrough, said cathode being traversed only by said heating current, means comprising a source of voltage connected between said line and said cathode for producing a time-constant electric field therebetween, and a magnet positioned with respect to said tube so as to produce a uniform time-constant magnetic field traversing the said tube in the direction of the common axis of the cathode and the delay line, whereby an oscillatory movement between said cathode and line is imparted to electrons emitted by said cathode.

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US95188A 1948-06-12 1949-05-25 Thermionic tube for amplification of ultrashort electric waves Expired - Lifetime US2623129A (en)

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US (1) US2623129A (fr)
DE (1) DE881532C (fr)
FR (1) FR967962A (fr)
GB (1) GB676630A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2758244A (en) * 1952-06-02 1956-08-07 Rca Corp Electron beam tubes
US2758243A (en) * 1952-06-02 1956-08-07 Rca Corp Electron beam tubes
US3029361A (en) * 1958-08-19 1962-04-10 Rca Corp High temperature plasma confinement using a travelling electromagnetic field
US3032676A (en) * 1957-02-19 1962-05-01 Raytheon Co Traveling wave tubes
US3076115A (en) * 1956-07-05 1963-01-29 Rca Corp Traveling wave magnetron amplifier tubes

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE973486C (de) * 1950-12-06 1960-03-03 Elektronik Ges Mit Beschraenkt Elektronenroehre fuer laengs einer wendelfoermigen Verzoegerungsleitung fortschreitende sehr kurze elektromagnetische Wellen
DE1026440B (de) * 1952-02-11 1958-03-20 Telefunken Gmbh Schaltung zum Betrieb einer elektrischen Entladungsroehre fuer sehr kurze elektrische Wellen
DE939586C (de) * 1952-11-27 1956-02-23 Siemens Ag Elektronenroehre fuer sehr hohe Frequenzen

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1877872A (en) * 1928-03-15 1932-09-20 American Telephone & Telegraph Production of short electric waves
US2122538A (en) * 1935-01-22 1938-07-05 American Telephone & Telegraph Wave amplifier
US2241976A (en) * 1940-04-25 1941-05-13 Gen Electric High frequency apparatus
US2300052A (en) * 1940-05-04 1942-10-27 Rca Corp Electron discharge device system
US2402184A (en) * 1941-05-03 1946-06-18 Bell Telephone Labor Inc Ultra high frequency electronic device contained within wave guides
US2439401A (en) * 1942-09-10 1948-04-13 Raytheon Mfg Co Magnetron oscillator of the resonant cavity type
US2511407A (en) * 1947-01-09 1950-06-13 Csf Amplifying valve of the progressive wave type
US2516944A (en) * 1947-12-18 1950-08-01 Philco Corp Impedance-matching device
US2541843A (en) * 1947-07-18 1951-02-13 Philco Corp Electronic tube of the traveling wave type

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB321306A (en) * 1928-10-17 1929-11-07 Richard Hindle An improved milling machine attachment

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1877872A (en) * 1928-03-15 1932-09-20 American Telephone & Telegraph Production of short electric waves
US2122538A (en) * 1935-01-22 1938-07-05 American Telephone & Telegraph Wave amplifier
US2241976A (en) * 1940-04-25 1941-05-13 Gen Electric High frequency apparatus
US2300052A (en) * 1940-05-04 1942-10-27 Rca Corp Electron discharge device system
US2402184A (en) * 1941-05-03 1946-06-18 Bell Telephone Labor Inc Ultra high frequency electronic device contained within wave guides
US2439401A (en) * 1942-09-10 1948-04-13 Raytheon Mfg Co Magnetron oscillator of the resonant cavity type
US2511407A (en) * 1947-01-09 1950-06-13 Csf Amplifying valve of the progressive wave type
US2541843A (en) * 1947-07-18 1951-02-13 Philco Corp Electronic tube of the traveling wave type
US2516944A (en) * 1947-12-18 1950-08-01 Philco Corp Impedance-matching device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2758244A (en) * 1952-06-02 1956-08-07 Rca Corp Electron beam tubes
US2758243A (en) * 1952-06-02 1956-08-07 Rca Corp Electron beam tubes
US3076115A (en) * 1956-07-05 1963-01-29 Rca Corp Traveling wave magnetron amplifier tubes
US3032676A (en) * 1957-02-19 1962-05-01 Raytheon Co Traveling wave tubes
US3029361A (en) * 1958-08-19 1962-04-10 Rca Corp High temperature plasma confinement using a travelling electromagnetic field

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GB676630A (en) 1952-07-30
DE881532C (de) 1953-07-02
FR967962A (fr) 1950-11-16

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