US3027487A

US3027487A - Electron discharge devices of the traveling wave type

Info

Publication number: US3027487A
Application number: US382024A
Authority: US
Inventors: Edward C Dench
Original assignee: Raytheon Co
Current assignee: Raytheon Co
Priority date: 1953-09-24
Filing date: 1953-09-24
Publication date: 1962-03-27
Anticipated expiration: 1979-03-27

Description

E. C. DENCH March 2 7, 1962 ELECTRON DISCHARGE DEVICES OF THE TRAVELING WAVE TYPE Filed Sept. 24, 1953 V v i i ELECT/EON BEAM OUTPUT v H QQ 4 NE viDQ Um F WC A C A W Y 5 E5 Pr 2 H 5 I a m w m a 5 r W w w, Z n 9 m 4 W 2 l n W 2V1 5V1 i gatgg 3,027,437 ELECTRON DliSCl-TARGE DEVKCES F THE TRAVELING WAVE TYPE Edward C. Dene-h, Needharn, Mass, assignor to Raytheon Company, a corporation of Deiaware Filed ept. 24, 1953, Ser. No. 382,024 24- Claims. (Cl. 315-395) This invention relates to a backward wave traveling wave tube oscillator and more particularly relates to means for producing oscillations in said tube of more than one frequency.

In United States Patent No. 2,863,092 of Edward C. Dench, issued December 2, 1958, a backward wave traveling wave oscillator is described which includes a periodic anode delay network of the strapped vane type, a continuous negative electrode spaced from and disposed substantially parallel to the anode network, and an electron gun for producing an electron beam which travels through the interaction space between the anode and the negative electrode.

The velocity of the backward component of a traveling wave varies with frequency in filter-type microwave structures, such as periodic loaded transmission lines (strapped vane structures, interdigital arrays, disk-loaded coaxial systems, etc.).

As the velocity of the electron beam is varied, substantial synchronism is obtained with the phase velocity of the first backward component of the traveling wave for a given frequency. As synchronism is obtained, oscillations will occur within the traveling wave tube. By varying the electron beam velocity, therefore, a variation in frequency of the traveling wave oscillator is obtained.

The average velocity of the electron beam is dependent upon the electric field E and the magnetic field B and is equal to the ratio E/B where E is further defined by the ratio of the anode-negative electrode voltage P to the distance d therebetween.

In accordance with one embodiment of this invention, the negative electrode of the traveling wave tube is inclined at an angle with respect to the periodic anode network so that the spacing d between the anode and negative electrode, instead of being uniform, gradually changes as the end of the tube remote from the output end is approached. As the distance d gradually changes, the strength of the electric field E, for a given anode-negative electrode voltage P, also varies. The beam velocity which is proportional to the value of E also varies over the length of the tube; since the frequency of oscillation of the tube is dependent upon the beam velocity, a band of frequencies is excited simultaneously. The width of this band is determined by the degree of slope of the negative electrode, while the mean frequency of the band is determined by the anode voltage P.

A voltage-tuned oscillator is thus provided which is capable of rapid adjustment to any mean frequency and of putting out a continuous band of frequencies in the vicinity of this mean frequency. The velocity may be varied by tapering the transverse magnetic field (if any), although it is somewhat more difficult in practice to control the distribution of the magnetic field B than the electric field. The magnetic field may be tapered regardless of whether or not the previously described method of varying the electric field 1's resorted to.

Also, in accordance with the invention, the negative electrode may be constructed so that the anode-negative electrode spacing is varied in discrete steps. In this case, frequencies corresponding to each discrete spacing of the anode from the negative electrode may be obtained. Moreover, the magnetic field (if any) likewise may be varied in discrete steps.

The foregoing and other features of the invention will become more apparent from the detailed description of certain specific embodiments which follows.

The description refers to the accompanying drawings wherein:

FIG. 1 is a curve illustrating certain operating principles of the traveling wave tube of the invention;

FIG. 2 is a central cross-sectional view of a traveling wave oscillator in accordance with the invention;

FIG. 3 is a schematic view of the traveling wave oscillator of FIG. 2;

FIG. 4 is an isometric view of a modification of the traveling wave oscillator of FIG. 2 in which the magnetic field is altered; and

FIG. 5 is a schematic view of a modification of the traveling wave oscillator of FIG. 2.

Referring to FIGS. 2 and 4 of the drawings, a traveling wave oscillator tube is shown which includes a periodic anode transmission network 10. This network includes an electrically-conductive backing plate 11 which extends lengthwise of the tube. A plurality of substantially rectangular anode vanes 12 is rigidly attached to backing plate 11 and extends perpendicular thereto, as shown in FIGS. 2 and 4. The free ends of vanes 12 are alternately connected by electrically-conductive straps 14 at points along the edges of said vane, in the manner in which magnetron-anode vanes are interconnected. The anode vanes 12, straps 14, backing plate 11, and the spaces bound thereby constitute a plurality of cavities or network sections which, in combination, constitute a signal wave transmission network having the characteristics of a bandpass filter.

The anode structure 10 is enclosed in an evacuated envelope comprising upper and

lower walls

17 and 18,

end walls

19 and 20 and side walls 21 and 22 (as shown in FIG. 4). Backing plate 11 is secured to wall 10 by soldering or by an appropriate fastening device.

An output coupling device 24 having inner and

outer conductors

25 and 26, respectively, extends through end wall 19 and is connected to anode structure 10. The outer conductor 24 is connected to the end of anode vane 12:: while the inner conductor 25 is attached to the adjacent anode vane 12b.

A cathode 28 is located adjacent the output end of the periodic anode network and has an electron emissive surface 29 presented to the free ends of the anode vanes. The cathode is supported by means of a compound cylindrical supporting member 31. An electrically-conductive wire or rod 32 connected at one end to the cathode heater coil extends through supporting member 31 exteriorly of the tube envelope. The details of this cathode and cathode supporting structure are set forth more fully in US. Patent No. 2,809,328 of E. C. Dench, issued October 8, 1957.

A collector electrode 33 is positioned in substantial alignment with the cathode at the end of the tube opposite from said cathode. This electrode, which intercepts the electrons of the electron beam traversing the interaction space, is supported with respect to wall 18 by supporting member 34 through which an electrical connection 35 external to the tube is brought.

A negative electrode 38, otherwise referred to as a. sole, is arranged coextensive with the free ends of anode vanes 12 and is spaced therefrom. Sole 38 comprises a substantially rectangular electrically-conductive plate positioned somewhat lower than the electron emissive surface 29 of the cathode. An aperture 39 slightly larger than the cathode is provided in the sole to permit the cathode structure to pass through. The sole may be provided with vertical sides which either approach or overlap the anode structure, as shown and described in the aforesaid (Ce U.S. Patent No. 2,809,328. These vertical edges serve to keep the electron beam centered in the system and keep the beam from diverting due to the mutual repulsion of the space charge along the tube length.

In accordance with the embodiment of the invention shown in FIGS. 2 and 3, the sole or negative electrode is inclined at an angle with respect to the anode so that the spacing between the anode and sole gradually decreases from d to d This feature will be enlarged upon subsequently. The sole is supported with respect to the tube envelope by means of a, pair of support rods 42 which extend through apertures in wall 18 and which are rigidly secured thereto by suitable connecting means 43. An electrical connection may be made to the sole by way of an extension 44 of rod 42.

A tapered attenuation is introduced into the region of the anode structure adjacent the far end thereof, as shown schematically in FIGS. 4 and 5. This attenuation may, as shown in FIG. 2, take the form of an attenuated coating 46 of a material such as graphite or iron which may be deposited by spraying, electroplating, or by other similar techniques. The eifect of introducing attenuation in a traveling wave oscillator is set forth more fully in a copending application of E. C. Dench for U8. Letters Patent, Serial No. 382,025, filed September 24, 1953.

A uniform transverse magnetic field is produced in a direction substantially perpendicular to the path of the electrons, that is, in a direction normal to the plane of the paper in FIG. 2, by means of a magnet, not shown in FIG. 2, which may be either of the permanent or the electromagnetic variety. For the device of FIG. 2 the magnet may be either a single magnet or a series of magnets of equal strength; for example, the magnet cores of FIG. 4, either with identical windings or with no winding at all, may be used in the tube of FIG. 2. The pole pieces of the magnet or magnets are positioned adjacent opposite side walls 21 and 22 of the tube of either FIG. 2 or FIG. 4.

There is no single predetermined phase velocity of propagation along a periodically loaded transmission network for any given frequency. Furthermore, the electric field associated with such networks does not vary sinusoidally with distance but must be analyzed as a set of Fourier components or space harmonics which travel in opposite directions with different phase velocities V where n is the number of the harmonic. The phase velocity V is given by wA lll+21rn where For filter circuits of this type there is an infinite number of space harmonics, some of which have positive phase velocities and some negative. When V is positive, the phase velocity is in the same direction as the energy or group velocity and the corresponding waves are referred to as forward or direct waves. When V is negative, the phase velocity is in a direction opposite to the energy velocity and the corresponding waves are referred to as reverse or backward waves. When the electron beam velocity is substantially equal to the phase velocity of some forward wave, energy carried by the traveling wave to the anode increases in the direction of motion of the beam and the device functions as an amplifier. When the electron velocity is synchronized with a backward wave, however, the traveling wave tube becomes an oscillator.

For a periodic structure such as shown in FIG. 2, and for most other signal wave transmission networks used in traveling wave tubes, t is a negative quantity. If it is and obviously is negative. Operation on the fundamental, therefore, is desirable in order to produce oscillations in the traveling wave tube.

The strength and direction of the magnetic field are such that electrons emitted from the cathode 28 and attracted toward the anode structure 10 (which is made positive relative to the cathode by insertion therebetween of a unidirectional source of voltage, not shown) move toward the collector electrode 33 along the path adjacent the free ends of anode vanes 12. Interaction of the electron beam with the proper space harmonic of the electromagnetic wave traveling along the periodic anode network will result in the production of oscillations within the traveling wave tube.

In FIG. 1, a typical dispersion curve 48 representative of a strapped vane periodic structure is shown. The phase velocity V normalized with respect to the velocity c of the light is plotted against wave length A.

Curve 48 is symmetrical about a straight line 49 of constant 1/, that is, 0:1. The portion lm of curve 48 above line 49 is that for the first space harmonic traveling in the same direction as the energy or group velocity while the portion mn of curve 48 represents the first backward harmonic (fundamental). The upper cutoff wave length is indicated as A If an electron beam at normalized velocity C/ V; is substantially synchronized with the phase velocity of a fundamental, oscillations will occur at a wave length M, as shown in FIG. 1. If the normalized beam velocity is changed to C/V oscillations will occur at a new wave length A and so forth.

The electron beam travels through the interaction space at an average velocity V given by where E is the electric field strength and B is the transverse magnetic field strength The electric field E, in turn, is given approximately by where The anode voltage P may be obtained by means of a source 50 of unidirectional voltage connected between the tube envelope (which is at the same potential as anode 10) and one of the connections 44 to sole 38, as shown in FIG. 2.

The distance d of the tube of FIGS. 2 and 4 varies gradually from d to d and the beam velocity V thus varies from E /B to E /B over the length of the tube. If B is held constant, either by using a permanent magnet or by maintaining fixed the excitation of one or more electromagnets, a change in the electrode spacing d will result in beam velocities V and V respectively. The normalized phase velocities C/V and C/V -which aresubstantially equal to the beam velocities V and V and therefore capable of producing the desired interac tioncorrespond, respectively, to wave lengths A and A at which oscillations are produced. In other words the traveling wave tube may be made to oscillate over a band of frequencies lying between A and A and the width of this band will depend upon the slope of the negative electrode with respect to the anode. The wider the band of operation the less gradual will be the change in spacing d with distance along the tube. The mean frequency of band is determined, of course, by the anode voltage P. By varying this voltage the velocity of the electron beam may be changed and the wave length, for any given distance a, is altered.

A voltage-tuned traveling wave oscillator is thus obtained which is capable of putting out a continuous band of frequencies in the vicinity of a readily variable mean frequency.

Although the distance d, as shown in FIGS. 2 and 3, is gradually decreasing as the end of tube remote from the output end is reached, the negative electrode 38 may equally well be tapered in the opposite direction so that d becomes gradually larger as the far end of the tube is approached.

Although the broad band oscillator thus far described depends upon the gradual variation of electric field strength E with distance along the tube, it is possible to gradually vary the distribution of the transverse magnetic field associated with the tube. This gradual variation of B with distance along the tube is achieved as shown in FIG. 4 in which a plurality of

U-shaped magnets

52a, 52b and 520 is arranged about the traveling Wave tube so that the pole pieces thereof lie adjacent opposite side walls of the tube. The magnets are shown as electromagnets energized by the application of a uni-directional source of voltage 56 applied in parallel across the terminals of windings 54a, 54b and so forth. The number of coil turns on successive magnets is gradually increased as the end of the tube remote from the output end is approached. In this way the fiux density B of each succeeding magnet is increased and a progressively increasing magnetic field is obtained. The uniformity of the taper of the magnetic field is partially determined by the number of magnets used, the spacing of the magnets, and the relative number of turns on the magnet coils. The progressively increasing magnetic field may also be obtained by the use of a plurality of permanent magnets of difiering values of flux density.

The mean frequency of operation of the traveling wave tube may be varied by varying the magnitude of the exciting voltage derived from source 56.

As in the case of the tapered electric field, previously described, the direction in which the magnetic field increases is immaterial and the strength of the transverse magnetic field may be increased as the output end of the tube is approached.

Both of the methods described of achieving oscillations over a considerable band width may be used concurrently rather than separately. For example, the negative electrode of the traveling wave tube of FIG. 4 may be inclined with respect to the anode structure in the manner shown in FIGS. 2 and 3.

In FIG. 5 a schematic illustration of a modification of the traveling wave tube of FIGS. 2 and 3 is shown. Instead of having a tapered negative electrode 38 which progressively approaches the anode, the negative electrode 38 consists of the discrete steps. One such step is shown in the negative electrode of FIG. 5 although any reasonable number of steps may be included therein. In FIG. 5 the negative electrode 33 is divided into two sections 38a and 38b spaced from the anode it) by distances al and d respectively. In this way, oscillations may be produced simultaneously at two frequencies corresponding, respec tively, to beam velocities E /B and E /B.

The same effect may obviously be produced by varying the transverse magnetic field strength B in two discrete steps. This may be accomplished for example, by use of two magnets of different strength of the type shown in FIG. 4, one positioned adjacent the region coextensive with step 38a of FIG. 5 and the other positioned adjacent the region corresponding to step 38b of the same figure.

Although the tubes thus far described have been of the magnetic type utilizing a transverse magnetic field, the principle of this invention is applicable to traveling wave tubes which have no such magnetic field.

This invention may be applied to other than linear traveling wave tubes. For example, a circular tube of the type shown in application for United States Letters Patent of Edward C. Dench, Serial Number 382,025, filed September 24, 1953, may be used. In such a tube, the tapered negative electrode would be of substantially spiral configuration so that the distance d between the negative electrode and the arcuate anode network may be progressively increased or decreased, as the case may be.

Although the tapered negative electrode of FIG. 1 has been shown as an auxiliary electrode or sole separate from the cathode, the negative electrode may take the form of a continuous cathode extending the length of the tube and similar to that described in United States Patent 2,651,001 of William C. Brown, issued September 1, 1953.

Finally, it is not essential that the electric or magnetic fields be varied continuously, so long as values of E and B corresponding to each of the desired frequencies in the band are obtained along the length of the tube.

This invention is not limited to the particular details of construction, material and processes described, as many equivalents will suggest themselves to those skilled in the art. It is, accordingly, desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

1. A wide band traveling wave electron discharge device comprising a periodic delay network for transmitting electromagnetic Wave energ output coupling means connected to one end of said periodic network, an electrode spaced from and substantially coextensive with said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with said wave energy including means for producing mutually perpendicular electric and magnetic fields in the .region of said path and substantially normal thereto, and means for varying the strength of said fields along said path for producing oscillations in said device at a plurality of frequencies.

2. A wide band traveling wave electron discharge device comprising a periodic delay network for transmitting electromagnetic Wave energy, output coupling means connected to one end of said periodic network, and means for introducing attentuation in a region adjacent the other end of said network, a cathode having an electron emissive surface, an auxiliary electrode spaced from and substantially coextensive with said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons originating from said cathode along a. path adjacent said network and in energy interacting relationship with said Wave energy including means for producing mutually perpendicular electric and magnetic fields in the region of said path substantially normal thereto, and means for varying the strength of said fields along said path for producing oscillations in said device at a plurality of frequencies.

3. A Wide band traveling Wave electron discharge device comprising a periodic delay network for transmitting electromagnetic wave energy, output coupling means con nected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a ne ative potential with rmpect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with said wave energy including means for producing an electric field in the region of said path substantially normal there to, and means for varying the strength of said field along said path for producing oscillations in said device at a plurality of frequencies.

4. A wide band traveling wave electron discharge device comprising a periodic delay network for transmitting 7. electromagnetic wave energy, output coupling means connected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with said wave energy including means for producing an electric field in the region of said path substantially normal thereto, and means for progressively varying the strength of said field along said path for producing oscillations in said device at a plurality of frequencies.

5. A wide band traveling wave electron discharge device compri-sing a periodic delay network for transmitting electromagnetic Wave energy, output coupling means connected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a. negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with said wave energy including means for producing an electric field in the region of said path substantially normal thereto, and means for varying in discrete steps the strength of said field along said path for producing oscillations in said device at a plurality of frequencies.

6. A wide band traveling Wave electron discharge device comprising a periodic delay network for transmitting electromagnetic wave energy, output coupling means connected to one end of said network, means for direct ing a beam of electrons along a path adjacent said periodic network and in energy interacting relationship with said wave energy, a continuous electrode arranged coextensive with said periodic network and maintained at a negative potential with respect thereto, said electrode having a plurality of discrete portions, each of which is spaced from said network by differing amounts.

7. A wide band traveling wave electron discharge device comprising a periodic delay network for transmitting electromagnetic wave energy, energy coupling means connected only to one end of said network, a source of electrons, means for directing a beam of said electrons along a path adjacent said periodic network and in energy interacting relationship with said wave energy, said coupling means providing for extraction of said wave energy from said network, an electrode arranged coextensive with said periodic network and maintained at a negative potential with respect thereto, said electrode being inclined at an angle with respect to said network.

8. A Wide band traveling wave electron discharge device comprising a periodic delay network for transmitting electromagnetic wave energy, energy coupling means connected only to one end of said network, means for directing a beam of electrons along a path adjacent said periodic network and in energy interacting relationship with said wave energy, said coupling means providing for extraction of said wave energy from said network, an electrode arranged coextensive with said periodic network and maintained at a negative potential with respect to said network, means for producing a magnetic field transverse to said path of said electrons and including a plurality of magnets each of different field strength positioned along said path.

9. A wide band traveling wave electron discharge device comprising a periodic delay network for transmitting electromagnetic wave energy, energy coupling means connected only to one end of said network, means for directing a beam of electrons along a path adjacent said periodic network and in energy interacting relationship with said wave energy, said coupling means providing for extraction of said wave energy from said network, a continuous electrode arranged coextensive with said periodic network and maintained at a negative potential with repect thereto, means for producing a magnetic field trans verse to said path and including a plurality of magnets of different field strength positioned along said path in the order of their respective field strengths.

10. A wide band traveling wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said periodic network, an electrode spaced from and substantially coextensive with said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with said wave energy including means for producing mutually perpendicular electric and magnetic fields in the region of said path and substantially normat thereto, and means, for varying the strength of said fields along said path for producing oscillations in said device at a plurality of frequencies.

11. A wide band traveling wave electron discharge de-' vice comprising a periodic delay network of uniform pitch for transmittting electromagnetic wave energy, output coupling meansconnected to one end of said periodic network, an electrode spaced from and substantially coextensive with said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with backward components of said wave energy traveling in a direction opposite to that of said beam and including means for producing mutually perpendicular electrio and magnetic fields in the region of said path and substantially normal thereto, and means for varying the strength of said fields along said path for producing oscillations in said device at a plurality of frequencies.

12. A wide band traveling wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said periodic network, an electrode spaced from and substantially coextensive with said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with backward components of said wave energy traveling in a direction opposite to that of said beam and including means for producing mutually perpendicular electric and magnetic fields in the region of said path and substantially normal thereto, and means for increasing the strength of said fields along said path in the direction of said electron beam for producing oscillations in said device at a plurality of frequencies.

13. A wide band traveling wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said periodic network, and means for introducing attenuation in a region adjacent the other end of said network, a cathode having an electron emissive surface, an auxiliary electrode spaced from and substantially coextensive with said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons originating from said cathode along a path adjacent said network and in energy interacting relationship with said wave energy including means for producing mutually perpendicular electric and magnetic fields in the region of said path substantially normal thereto, and means for varying the strength of said fields along said path for producing oscillations in said device at a plurality of frequencies.

14. A wide band traveling wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said periodic network, and means for introducing attenuation in a region adjacent the other end of said network, a cathode having an electron emissive surface, an auxiliary electrode spaced from and substantially coextensive with said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons originating from said cathode along a path adjacent said network and in energy interacting relationship with backward components of said wave energy traveling in a direction opposite to that of said beam and including means for producing mutually perpendicular electric and magnetic fields in the region of said path substantially normal thereto, and means for varying the strength of said fields along said path for producing oscillations in said device at a plurality of frequencies.

15. A wide band traveling wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said periodic network, and means for introducing attenuation in a region adjacent the other end of said network, a cathode having an electron emissive surface, an auxiliary electrode spaced from and substantially coextensive with said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons originating from said cathode along a path adjacent said network and in energy interacting relationship with backward components of said wave energy traveling in a direction opposite to that of said beam and in-, cluding means for producing mutually perpendicular electric and magnetic fields in the region of said path substantially normal thereto, and means for increasing the strength of said fields along said path in the direction of said electron beam for producing oscillations in said device at a plurality of frequencies.

16. A wide band traveling Wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with said wave energy and including means for producing an electric field in the region of said path substantially normal thereto, and means for varying the strength of said field along said path for producing oscillations in said device at a plurality of frequencies.

17. A wide band traveling wave electron discharge de-. vice comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with backward components of said wave energy traveling in a direction opposite to that of said beam and including means for producing an electric field in the region of said path substantially normal thereto, and means for varying the strength of said field along said path for producing oscillations in said device at a plurality of frequencies.

18. A wide band traveling wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relations 1p with backward components of said wave energy travelling in a direction opposite to that of said beam and including means for producing an electric field in the region of said path substantially normal thereto, and means for increas- 10 ing the strength of said field along said path in the direction of said electron beam for producing oscillations in said device at a plurality of frequencies.

19. A wide band traveling wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with said wave energy including means for producing an electric field in the region of said path substantially normal thereto, and means for progressively varying the strength of said field along said path for producing oscillations in said device at a plurality of frequencies.

20. A wide band traveling wave electron discharge de vice comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with backward components of said wave energy traveling in a direction opposite to that of said beam and including means for producing an electric field in the region of said path substantially normal thereto, and means for progressively varying the strength of said field along said path for producing oscillations in said device at a plurality of frequencies.

21. A wide band traveling wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with said wave energy including means for producing an electric field in the region of said path substantially normal thereto, and means for varying in discrete steps the strength of said field along said path for producing oscillations in said device at a plurality of frequencies.

22. A wide band traveling wave electron discharge device comprising a periodic delay network of uniform pitch for transmitting electromagnetic wave energy, output coupling means connected to one end of said network, an electrode spaced from and substantially coextensive with said periodic network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with backward components of said Wave energy traveling in a direction opposite to that of said beam and including means for producing an electric field in the region of said path substantially normal thereto, and means for varying in discrete steps the strength of said field along said path for producing oscillations in said device at a plurality of frequencies.

23. A wide band traveling wave electron discharge device comprising a periodic delay network for transmitting electromagnetic wave energy, output coupling means connected to one end of said periodic network, an electrode spaced from and substantially coextensive with said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network and in energy interacting relationship with backward components of said wave energy traveling in a direction opposite to that of said beam and including means for 1 1 producing mutually perpendicular electric and magnetic fields in the region of, said path and substantially normal thereto, and means for varying the strength of said fields along said path for producing oscillations in said device at a plurality of frequencies.

24. A Wide band traveling Wave electron discharge device comprising a periodic delay network for transmitting electromagnetic wave energy, output coupling means connected to one end of said periodic network, an electrode spaced from and substantially coextensive With said network, said electrode being maintained at a negative potential with respect to said network, means for directing a beam of electrons along a path adjacent said network References Cited in the file of this patent FOREIGN PATENTS France May 24, 1950 France Feb. 21, 1951 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION,

Patent No. 3,027,487 March 27, 1962 Edward C. Dench It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

umn 3, line 3, for "diverting" read diverging Signed and sealed this 9th day of October 1962.

(SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesting Officer Commissioner of Patents