Abstract: A circuit assembly for temperature-dependent cathode current tracking in traveling-wave tubes having control electrodes and cathodes with a predetermined cathode current, in combination with a power supply, includes a temperature-dependent network thermally coupled to a given point of the traveling-wave tube for measuring the actual temperature of the tube, and an electronic control circuit in the power supply connected to the temperature-dependent network for keeping the predetermined cathode current substantially constant by varying the voltage at the control electrode of the tube.

Abstract: A millimeter coupled cavity travelling wave tube has its slow wave structures formed by a hobbing process. In a preferred construction, each slow wave structure is made of two individual halves each extending for the length of the structure. Each half contains one half of each cavity and one half of each beam hole and all of the portions of cavity and portions of beam hole in each half are formed in one hobbing operating. Coupling holes between cavities are formed where required by a process (e.g. spark erosion) separate from hobbing and if ferrules or drift tubes are required to extend out of the cavity separating walls in the finished tube, the beam coupling holes are made oversized and individual ferrules are brazed into position. The two halves of the slow wave structure are united by furnace brazing.

Abstract: To ensure stability of tubes comprising a delay line of the ceiling and ring type or of the ceiling and bar type, resonating slits are disposed in the ceilings of the line.

Abstract: Method and apparatus for modulating coherent radiation generated by an orotron in accordance with a low voltage control signal applied to the diffraction grating to vary the grating-to-cathode voltage from the cathode-to-collector voltage over a selected voltage range determined by the maximum and minimum values of the control voltage. For amplitude modulation, the grating-to-cathode voltage is varied within a voltage range between a lower voltage at which the orotron output power starts to fall abruptly and a cutoff voltage at which coherent radiation ceases. For frequency modulation, the grating-to-cathode voltage is varied within a voltage range, including the point of maximum power output, where there is a minimum change of output power with a change in the grating-to-cathode voltage.

Abstract: A travelling wave tube has an output lead passing through a tubular output arm to a cap provided at the end of the arm. The cap has a cylindrical wall of ceramic material and is completed by a flanged plate of metal, to which said output lead is attached. When coupled to a waveguide, the travelling wave tube output arm enters an entry hole in one wall of the waveguide while the cap thereof abuts a matching ridge provided on the interior of the opposite wall of the waveguide. A small recess in the ridge locates the cap, the cylindrical wall of which acts as a window through which travelling wave tube output may pass into the interior of said waveguide.

Abstract: A double-coupled ladder circuit for a traveling-wave tube has been a slow-wave circuit formed of a pair of combs, each cut from a single piece of metal. Transverse grooves are cut in each piece to form teeth and axial grooves are cut in the ends of the teeth. The two combs are joined at teeth ends to form a ladder with the transverse grooves aligned to form cavities and the axial grooves aligned to form a beam passageway. Coupling apertures are cut in both sides of a first set of alternating ladder rungs and a second set of apertures cut in the comb backing members over the second, interleaved, set of rungs. Thus, each cavity is coupled on two opposite sides to its preceding cavity and on the two remaining sides to its following cavity. The double coupling provides increased bandwidth and efficiency. Finally, side plates are affixed to cover the apertures, complete the cavity walls and form the vacuum envelope.

Abstract: A coupled-cavity slow-wave circuit for a millimeter-wave TWT is formed by forming cavities through a metallic bar or half-cavities in a pair of comb-shaped bars. The ends of the cavities are covered by cover members, one of which has a longitudinal groove to form "in line" coupling apertures between cavities.

Abstract: A helix-type delay line borne by a conical surface. The internal surface of a sleeve has grooves into which are inserted dielectric supports of constant height that are affixed to the helix-type delay line, and the depth of the grooves increases with the diameter of the line.

Abstract: The object of the invention is to provide a traveling wave tube with increased linearity to avoid intermodulation of signals being amplified. In a traveling wave tube 10, as shown in FIG. 1, the slow wave structure is a helix (18) including a sever (21). A dynamic velocity taper is provided by gradually reducing the spacing (26) between the repeating elements of the slow wave structure which are the windings of helix (18). The reduction takes place between Zo indicated by line 23 and Z.sub.s which coincides with the output point of helix (18) as indicated by the line (22). The spacing (26) begins to decrease at Z.sub.o and is decreased by up to about 5% at Z.sub.s. The spacing (26) between the repeating elements of the slow wave structure is ideally at an exponential rate because the curve (27), as shown in FIG. 3, increases from Z.sub.o to Zs the point of maximum efficiency and power, at an exponential rate. FIG. 3 shows a coupled cavity traveling wave tube having cavities 32 through 37.

Abstract: A delay line assembly for high-performance traveling-wave tubes having an electron beam generating system and an electron beam collector, includes a copper vacuum enclosure, a delay line in the form of a ring ribbon conductor disposed in the vacuum enclosure between the electron beam generating system and the electron beam collector, and a plurality of dielectric mounting rods extended parallel to the ring ribbon conductor in the vacuum enclosure for supporting the delay line, the ring ribbon conductor being formed of a relatively more highly thermally stressed tungsten part and a relatively less highly thermally stressed molybdenum part.

Abstract: A tilt-angle electron gun provides a conical beam of electrons for injection into an axially aligned magnetic field of a gyrotron tube. The beam is formed by an electrostatic lens system for focussing and accelerating the electrons within a magnetically shielded region. The conical beam is substantially monoenergetic and laminar so that after injection into the magnetic field the resulting hollow beam has gyrating electrons which have an axial velocity spread sufficiently low for high efficiency gyrotron amplification.

Abstract: This invention refers to a traveling-wave tube with cylindrical evacuated sheath 3, which is surrounded by a permanent-magnet system including pole shoes 1 and magnet rings 2 inserted between the pole shoes, while pole shoes 1 inserted in evacuated sheath 3 and the parts of them that surround beam axis 7 are designed as small tubes 4. Every second pole shoe is coupled as an active pole shoe 1 to magnet ring 2, and pole shoes 5 that are inserted between are connected with evacuated sheath 3. This traveling-wave tube is capable of focusing with greater efficiency and at higher frequencies than existing systems. This invention also provides that active pole shoes 1, which are coupled to magnet rings 2, are made of magnetic metal and that at least front ends 8 of small tubes 4 are made of non-magnetic metal. In addition, pole shoes 5 inserted between are made of non-magnetic and their small tubes 6 of magnetic metal.

Abstract: The invention provides a travelling wave tube comprising means for suppressing parasite oscillations and these means are formed by auxiliary helical delay lines placed inside the sleeve in the gaps between two adjacent dielectric supports, periodically fixed to the sleeve by metal supports and without contact with the main helical delay line.

Abstract: The "comb-quad" slow-wave interaction circuit for a traveling-wave tube consists of a pair of metallic ladders whose rungs cross, the rungs of one ladder passing through the spaces between the rung of the other ladder.The phase velocity of the circuit wave is tapered to a lower value at the output end by gradually enlarging the axial open spaces between the longitudinal bases of the ladders and the surrounding envelope. The periodic elements of the ladders are all exactly alike, simplifying the construction.The slowing of the wave velocity is greater at the lower-frequency end of the passband, providing improved efficiency over the operating band.

Abstract: A travelling wave tube arrangement is provided in which in order to support and cool the collector thereof the latter is cradled between two slabs of beryllium oxide attached to the walls of a channel in a block of copper, which walls are inclined in V-fashion. A further slab of beryllium oxide is provided above the collector. This last mentioned slab is attached to a flexible copper alloy wall which is dependent from a copper alloy plate which extends across the top of the channel. The plate is brazed to the block. A screw passing through the plate exerts pressure upon said flexible wall which in turn urges the beryllium oxide plate carried thereby towards the collector thus pressing the latter between the three beryllium oxide plates to form a electrically insulating support of good thermal conductivity.

Abstract: A permanent-magnet-focused linear-beam high power millimeter-wave tube is externally adjustable for optimum electron beam optics during initial tube operation. The adjustment is made possible by providing an enlarged cavity within the cathode polepiece within which is housed a confined-flow magnetically-focused electron gun, and a cylindrical insert of magnetic material axially symmetrically disposed about the gun and in spaced relationship to and adjacent the gun insulator envelope. The insert may comprise iron or a radially magnetized permanent magnet, either alone or in combination, and more than one insert of magnetic material may be concentrically employed. In this manner, and by movement of the insert axially within the cavity toward and away from the gun, a finely controllable smooth adjustment of the beam diameter in the beam-microwave interaction region of the tube is effected over a wide range during initial operation.

Abstract: A dual-mode electron gun for a traveling-wave tube is disclosed which selectively generates an electron beam of two different cross-sectional areas. The electron gun includes radially inner and annular control grids as well as a shadow grid disposed between the cathode and the control grids along the electron beam path. The shadow grid is provided with a suppressor ring which precludes electron emission from an annular portion of the cathode immediately radially outwardly of the cathode region over which the inner control grid projects, thereby eliminating generation of a spurious beam portion radially outwardly from the desired smaller cross-section beam.

Abstract: A diffraction radiation generator in which a ribbon electron beam is directed over a diffraction grating within an open resonator at a selected velocity to generate coherent radiation. After passing through the open resonator, the ribbon beam is directed through aligned slits in two or more conductive elements to a collector. Progressively negative voltages relative to the grating voltage can be applied to the elements and the collector to decelerate the electrons forming the ribbon beam and thus minimize heating of the collector and increase the operating efficiency of the generator. Also, the elements and the collector can be utilized to analyze the ribbon beam.

Abstract: A traveling-wave tube having a cylindrical vacuum envelope surrounded by a permanent-magnet system of ring-shaped pole washers and magnet rings respectively disposed therebetween and having opposite polarizations alternatingly in axial direction, which includes spacer rings formed of nonmetallic material surrounding the cylindrical vacuum envelope and spacing the magnet rings therefrom, corresponding magnet rings and spacer rings being soldered together into respective strong and stable units.

Abstract: A source of coherent electromagnetic radiation capable of generating or amplifying waves in the centimeter, millimeter, and submillimeter wavelength range. An annular beam of gyrating electrons is produced which is then compressed to its paraxial position by means of a solenoid magnetic field around the wave-guide. This electron beam is also subjected to a transverse motion in an interaction region by a longitudinal rippled (wiggler) magnetic field. Such a field is generated by a periodic assembly of rings magnetized in the axial direction. The electron beam during its accelerated motion generates or amplifies coherent electromagnetic radiation in the centimeter, millimeter, or submillimeter range.

Abstract: It is an object of the invention to provide a spent particle collector which will maintain its structural integrity when raised to a high temperature although constructed of materials having widely different coefficients of expansion. The collector is comprised of one or more axisymmetric stages, each stage comprising a subassembly. A subassembly includes an inner pyrolytic graphite ring, a transition ring, a ceramic insulator ring and an outer metal ring which forms part of the wall of the collector. Each transition ring is of a ductile metal having high thermal conductivity and is provided with an annular sputter shield wall extending toward the source of spent particles and, where necessary, a trough in the other surface to enclose the sputter shield of the next adjacent transition ring. A plurality of radial extending slots are provided in a transition ring to form segments which are retained in their position by the sputter shield.

Abstract: Method for laser beam amplification by means of free electron laser techniques. With wiggler magnetic field strength B.sub.w and wavelength .lambda..sub.w =2.pi./k.sub.w regarded as variable parameters, the method(s) impose conditions such as substantial constancy of B.sub.w /k.sub.w or k.sub.w or B.sub.w and k.sub.w (alternating), coupled with a choice of either constant resonant phase angle or programmed phase space "bucket" area.

Abstract: A buffer is provided for protecting the electron beam collector of a traveling wave tube. The collector comprises an elongated tubular wall, an elongated tubular insulating wall of one type of material, an elongated cylindrical electrode of another type of material coaxially positioned within the insulating wall, and the buffer interposed between the electrode and the insulating wall. The buffer comprises a continuous web of buffer material capable of being bonded to dissimilar insulating wall material and electrode material. The web having an alternating pattern of corrugations, the vertices of the corrugations are generally planar which define two generally parallel, planar surfaces which in turn are adapted for bonding to the insulating wall and the electrode.

Abstract: Apparatus for spark perforation of sheet material comprising spaced apart first and second electrodes which define between them a sparking zone through which sheet material to be perforated can be moved in a predetermined direction, and in which the portion of the first electrode which is nearest to the nearest portion of the second electrode is located between an overlap position upstream of the second electrode in the direction of movement of the sheet by a distance of 1 mm and an offset position also equal to 1 mm in the direction of movement of the sheet, and means for guiding the sheet through the sparking zone along a path closer to said second electrode than said first electrode.

Abstract: A gyrotron traveling-wave device including quarter wavelength anti-reflece dielectric layers to enhance microwave absorption. A drift tube made from a hollow waveguide is positioned within the gyrotron to surround an electron beam passing from an electron gun to a cavity. A plurality of parallel highly lossy dielectric suppressor rings are interspaced with a plurality of conductive rings positioned to surround the electron beam and located within the waveguide. An anti-reflective layer is formed on the suppressor rings to enhance the absorption by the rings of radiation due to parasitic oscillations by reducing reflections of incident radiation from the suppressor rings. In an alternate embodiment, one or more suppressor rings including an anti-reflecting layer are located within the cavity.

Abstract: There is disclosed a traveling wave tube with a slow wave structure having means for frequency and directionally sensitive wave amplification. The slow wave structure includes a conductive helix coaxially mounted within a conductive tubular housing and a conductive support structure longitudinally disposed within the housing and extending transversely from the helix to the housing. In some embodiments, the support structure is combshaped and in one embodiment is a helical ridge wound in registration with and in the same sense as the helix. The pitch of the housing and a preselected parameter of the support structure are simultaneously varied along the length of the helix such that a wave at a given frequency band traveling along the slow wave structure in a first direction is preferentially amplified with respect to waves traveling in an opposite direction.

Abstract: A coupled-cavity delay line for traveling-wave tubes is provided with a cooling system which permits heat distribution along the entire length of the delay line and ensures that the outer surface of the vacuum enclosure is isothermal. The cooling system consists of a cylindrical sleeve containing heat pipes. The cylindrical sleeve is located between the external wall of the resonant cavities and the permanent magnets. The heat pipes are disposed at uniform angular intervals within the double-walled sleeve and extend lengthwise along the delay line.

Abstract: A cathode/grid assembly for effecting a dual power mode electron gun for use with a traveling wave tube. The conventional "shadow grid" is both electrically and mechanically isolated from the cathode. A variable voltage source is connected to the shadow grid to bias it slightly above or slightly below the cathode potential, depending on the power mode. The electron emitting surface area of the cathode is the same in both modes. By changing the bias on the shadow grid, the transverse beam temperature may be increased to compensate for the reduced space charge density of the low power mode. Thus, the diameter of the low power beam is substantially the same as the diameter of the high power beam. This ensures good beam transmission and high electron beam rf interaction in the low power mode.

Abstract: Apparatus for compensating the injurious increase of the cathode current occurring during the initial operation period of a travelling-wave tube when, during successive warming-up, the grid first approaches the cathode and then assumes the nominal distance therefrom. The apparatus includes a distance control device measuring the deviation between the actual grid-cathode distance and the nominal distance and generating a control signal proportional to the deviation for reducing the value of the grid voltage.

Abstract: Apparatus for starting and operating a discharge lamp includes a starting device having bimetals and a rigid conductive member forming a switch, a ballast coupling the switch to an AC source and a discharge lamp and a spark gap each shunting the starting device with the starting device bimetals and rigid conductive device hermetically sealed in a vacuum.

Abstract: A meander line slow wave structure mounted on ceramic bars for a microwave evice such as an injected beam crossed-field amplifier includes frequency selective attenuator means which will preferentially attenuate waves at frequencies near and within the stopband of the slow wave structure by the placement of side absorber bars of attenuating material adjacent to the outer side surfaces of a plurality of meander line finger segments. The frequency selective absorber material, in its preferred form, comprises a beryllia and silicon carbide ceramic composition which additionally adapted to accommodate metallic absorber top plates, nichrome films, and slotted side ring configurations.

Abstract: A tubular ring-bar slow wave structure is provided. The structure includes a plurality of axially spaced, coaxially aligned, generally parallel metallic rings connected by a plurality of generally axially parallel, alternately spaced metallic bars. The structure also includes a plurality of axially spaced, coaxially aligned, generally parallel dielectric support rings, each of which has a width that is narrower than the width of a metallic ring.

Abstract: The substrate is ladder shaped and is located between a serpentine metallic meander line conductor and a metallic ground plane. Conductive shields are disposed in slot-like openings of the substrate between adjacent parallel transverse segments of the meander line to decrease dispersion and increase the bandwidth to a full octave.

Abstract: A termination device for absorbing RF energy waves in the termination chamber of a traveling wave tube. The termination device is formed by modifying two wedge shaped termination devices of the prior art. Specifically, two well known single wedge termination devices are sliced in half to produce two wedges each one half the thickness of the prior art single wedge device. The two halves are positioned with their newly formed surface, formed by the slicing, in opposed facing contact. The new double wedge thus has the same thickness as the prior single wedge and is readily accommodated within the termination chamber. The double wedge termination device greatly reduces small signal gain variations across the operating frequency band of the traveling wave tube.

Abstract: This oscillator comprises a periodic structure line constituted by a succession of vanes having an orifice in which propagates a linear electron beam. This line is placed over a cavity constituted by a straight parallelepiped which has a rectangular base, whose dimensions are determined in such a way that it behaves like a waveguide at the cut-off frequency, along the longitudinal axis of the line and on a transverse magnetic or TM.sub.mn mode with m=1, 3, 5 etc. and n=1, 2, 3, 4 etc. Coupling slots are provided on the cavity between two successive vanes and in a gap between pairs of vanes. The anode voltage of the beam and the distance between two successive vanes are selected in such a way that the cavity resonates at the cut-off frequency and on the .pi. mode. Applications include measuring oscillators and heterodyne radar transmitters and receivers.

Abstract: An improved slow wave circuit especially useful in backward wave oscillators includes a slow wave circuit (10) in a waveguide (12) as shown in FIG. 1. The slow wave circuit is comprised of rings 11 disposed between and attached to respective stubs (13,14). The stubs (13,14) are attached to opposing sidewalls of the waveguide (12).To the end that opposed, interacting magnetic fields will be established to provide a very high coupling impedance for the slow wave structure, axially orientated bars (20) are connected between rings in alternate spaces and adjacent to the attachment points of stubs 13. Similarly, axial bars (21) are connected between rings in the spaces which do not include bars (20) and at points adjacent to the attachments of bars (21).FIG. 2 shows the current loops (22,23) available because of the inventive structure.FIG. 3 shows that rings 11 may be half rings of 180.degree. arc.FIG. 4 illustrates that the rings or half rings (11) with stubs (13,14) may be formed of flat metal ribbons.

Abstract: Two coupled cavity type, slow-wave circuits are separated, with a drift space section between them. An electron beam and an electromagnetic wave, which do not interact with each other, over a certain length, are in the drift space. A waveguide type non-reflective termination structure has a waveguide axis directed in the same direction as the electron beam and is coupled to the cavity, slow-wave circuits with respect to a high frequency wave disposed in the drift space section. With such a construction, a traveling wave tube is formed with a PPM focusing and with a non-reflective termination structure includes a waveguide member having a through-hole for passing an electron beam and two waveguides formed on the opposite sides of the through-hole. A lossy ceramic member is disposed within one of the two waveguides for a forwardly traveling wave and another lossy ceramic member is disposed in the other waveguide for a backwardly traveling wave.

Abstract: A slow-wave circuit suitable for a high-frequency traveling-wave tube has an array of metallic ladder rungs extending transversely across an elongated envelope and not in contact with the envelope except at the ends of the rungs. The envelope has a cross-shaped section to provide a fundamental backward wave. The rungs preferably have aligned apertures to pass a beam of electrons in traveling-wave interaction with the circuit.By making the rungs transversely broader than a critical value, the lowest passband of the circuit has poles of impedance at both its ends, whereby more efficient interaction is obtained, along with greater stability.

Abstract: This invention concerns a slow-wave circuit which is electrically equivalent to the well-known folded-waveguide or coupled-cavity circuit with staggered coupling slots. The central portion of the circuit is a metallic ladder. The ladder rungs are wide and flat to form the equivalent of flat cavities. The rungs have axially aligned holes thru their centers for beam passage. A pair of coupling ladders are joined to opposite sides of the central ladder. They have apertures or recesses spaced at twice the pitch of the central ladder; the recesses are aligned to provide a coupling duct between each pair of adjacent cavities, and cavity-closing walls at the ends of the pair. The coupling recesses in the two coupling ladders are staggered by the cavity pitch so that the coupling ducts are on alternating sides of the cavities.

Abstract: Travelling wave tube, including a cylindrical vacuum shell having an outer diameter, a permanent magnet system surrounding the cylindrical vacuum shell including ring-shaped pole shoes having inner and outer diameters, magnet rings having inner and outer diameters and forming pairs with the pole shoes, each of the magnet rings being alternatingly disposed between two pole shoes in axial direction and being poled in opposite sense with respect to the next magnet ring, the inner diameters of the pole shoes being closely fitted around the vacuum shell and being smaller than the inner diameters of the magnet rings, the outer diameters of the magnet ring being larger than the outer diameters of the pole shoes, and a centering and retaining ring being adjacent to and in contact with each of the pole shoe and magnet ring pairs for centralizing the inner diameters of the pole shoes to the outer diameters of the magnet rings and for centralizing the inner diameters of the pole shoes and the outer diameters of the magn

Abstract: In a travelling wave tube in which the delay line (1) is constituted by a sequence of double resonator cavities (15) alternating with the pole pieces (3) of the focusing system, the invention provides for the purpose of limiting the interception of electrons by the line an increase in the diameter of the magnetic material collars (30, 40) terminating said pieces, as well as the wall (16) of the cavities on the side of the tube axis. This increase takes place in stages, a collar (40) having the same diameter as the collar (30) which follows it in the beam propagation direction.

Abstract: The present invention relates to multistage vacuum collectors for ultra-high frequency tubes.Each electrode of the collector comprises two walls which are axially symmetrical with respect to the beam propagation axis and which are superimposed along said axis. The retarding path of the electrons due to the decreasing potentials of the electrodes is thus located in a small volume space between the facing walls of two adjacent electrodes. A plurality of permanent magnets positioned outside the vacuum enclosure above the final electrode produce an asymmetrical magnetic field with respect to the propagation axis.Application to travelling-wave tubes and klystrons.

Abstract: High-power linear-beam electron tubes require an extended uniform magnetic field to focus their beam in an elongated cylinder. When permanent magnets are used to energize the magnet structure, there is inevitably a leakage field outside the main flux-return path. The leakage field can refocus the beam in the tube's collector, damaging it. When the collector has air-cooling fins, it is not practical to shield it completely with magnetic material. In the invention, the leakage field is reduced by making the energizing magnet at the collector end axially magnetized and the magnet at the cathode end radially magnetized. Also, a shield around the outside of the fins may be added.

Abstract: A helical microwave delay line for a travelling-wave tube, constituted by a conductor held in the envelope of the tube by insulating bars. The width of the conductor in contact with the supporting bars increases along the tube axis, particularly towards the microwave energy output.

Abstract: A collector for use in a travelling wave tube includes a central metallic re that has a peripheral ceramic insulator with the central metallic core having a plurality of circumferentially spaced primary slots extending inwardly from the periphery and an equal number of secondary slots extending perpendicular to the primary slots adjacent the periphery of the electrode. The primary slots define a plurality of fingers and the secondary slots act as hinges for the fingers.

Abstract: A power supply control circuit is especially useful for a traveling wave tube, although it may also be used anyplace where desirable. An a-c power voltage is supplied to an input of the control circuit, where its frequency is multiplied to become a voltage having a period which is no greater than the duration of a power voltage fluctuation which might damage the traveling wave tube, unless corrected. The wave form of the multiplied frequency is shaped to provide a comparison voltage wave form, which is compared with a reference voltage. The a-c power voltage applied to said traveling wave tube is controlled responsive to the output of the comparison means.

Abstract: A regulated power supply for high voltage pulsed loads. An AC main or inverter circuit feeds the primary of a transformer which has a tapped secondary. The full secondary voltage is rectified through a diode to charge a main capacitor through a ground-end, low-voltage solid state control circuit. A sensing circuit detects the desired level of main capacitor charge and controls the solid state conductive element into current cutoff, by injecting a voltage step which holds off further main capacitor charging until the next load current pulse. The solid state circuits control operate at low level (ground-end of the high voltage main capacitor) and residual power supply energy is automatically shunted to an unregulated tapped output.

Abstract: A variable pitch delay line for a travelling wave tube, is constituted by cells constructed in waveguide sections in which takes place the propagation of the electromagnetic waves which are used in the operation of the tube. All the cells are constituted by the same components, namely tops or covers, a ring, supporting rods for the ring and a short-circuit. The variable pitch is obtained by expansion or contraction of the dimensions within the guide cross-section. A significant improvement of the tube efficiency is obtained by the use of lines formed from three sections with different pitches, which succeed one another along the path of the beam, whereof the second section has a smaller pitch and the third section a larger pitch than the first section.

Abstract: A slow-wave, cyclotron-type, travelling-wave-tube amplifier in which the m-wave interaction is the result of a Weibel-type instability. The travelling wave is slowed down in its propagation through the waveguide by a dielectric liner located on the inner wall of the waveguide. The bunching mechanism is the result of the V.sub..perp. .times.B.sub..perp. Lorentz force.

Abstract: In a microwave tube of the type wherein an electron beam emitted by an electron gun is focused and caused to interact with an input high frequency wave at a high frequency circuit unit by magnetic flux generated by a periodic permanent magnet assembly, and the electron beam after the interaction is collected by a collector unit, the portion connected to the output unit of the high frequency circuit unit comprises a column-shaped waveguide member having an end surface comprising a portion of the wall of a cavity at the end of the high frequency circuit unit, the member being bored with a central aperture at the center axis to allow electron beam to pass from the electron gun to the collector unit. A waveguide for guiding the electromagnetic waves from the end surface to the output unit is also provided, and the end surface is shaped like a fan.