Electron beam generation and propagation typically, a high power gyrotron uses mig. A linear electron beam between the cathode and collector is established within a klystron twt amplifier twta. Microwave tubes mwts continue to be important despite competitive incursion from solidstate devices ssds. Output frequencies range from about 20 to 527 ghz, covering wavelengths from microwave to the edge of the terahertz gap. Tubes versus semiconductors electron tubes electronics. Nonlinear analysis of beamwave interaction in a planar. Whereas the latter tubes use a linear electron beam, the magnetron directs its electron beam in a circular pattern by means of a strong magnetic field.
In a klystron the interaction between the input rf field and the electron beam causes velocity modulation and bunching of. Microwave devices with electron wave interaction 56. Their efficiency increases as the space charge in the beam decreases. Amplification is done through the prolonged interaction between an electron beam and radio frequency.
Electron beam traverses the length of the tube and is parallel to the electric field. The electron beam bunching already starts at the beginning of the helix and reaches its highest expression on the end of the helix. If the electrons of the beam were accelerated to travel faster than the waves traveling on the wire, bunching would occur through the. Once again, cavity resonators are used as microwave frequency tank circuits, extracting energy from the passing electron beam inductively. Microwave power generated in the delay line grows exponentially with a distance along its axis of symmetry. Multivelocity electron beam as a source of microwave oscillations in the collector region of a traveling wave tube article pdf available in technical physics 5810. The electron beam is generated by mig at the cathode and is accelerated towards the anode to form an electron beam of suitable parameters and passes through the region for interaction with the r. Microwave tubes can be broadly classifies into two categories 1. In 1897 lord rayleigh solved the mathematical boundaryvalue problem of electromagnetic waves propagating through conducting tubes and dielectric rods of arbitrary shape. Typical output powers range from tens of kilowatts to 12 megawatts. A microwave slowwave circuit that supports a traveling wave of electromagnetic energy with which the electron beam can interact. The equations describing the interaction processes have been formulated within the twodimensional linear theory and solved using the dispersionequation approach and the successive approximation method.
The operating frequency of klystrons and magnetrons is set by the. The sheet beam within one rf beam wavelength is represented by uniform rectangular charged discs for confined flow of the beam, and the discs are tracked in small distance steps of forward integration. We have used fea to design the magnet stacks to achieve predetermined axial field profiles. Availability of gaas, sic, and ganbased broadband and mediumpower ssds up to wband frequencies greatly affected the domain of mwt table 1. Electronwave oscillators with a retarding field 62. Beam space charge is measured by a quantity called perveance, useful in the design of electron guns, and defined as the ratio of the beam current to the 32power of the voltage. In a linear beam tube, the electron beam travels in the same direction as the magnetic field. Electron wave oscillators with a retarding field 62. Nonlinear space charge wave theory of distortion in a klystron. Besides, the electron beamplasma system showed great importance via plasma generation, design of microwave tubes waveguides, explanation of natural phenomena that occur in space and solar plasmas, material studies, compact torus formation, generation of xray.
Interaction of spacecharge waves in an electron beam with. Traveling wave tubes twts amplify radio frequency waves by converting electron beam energy into microwave energy. Pdf multivelocity electron beam as a source of microwave. Travelling wave tubes are broadband microwave devices which have no cavity resonators like klystrons. In this paper a simple treatment of excitation of electromagnetic waves in a slow wave structure, viz. The major classifications of linear beam tubes are shown in figure 6. Figure 3 below shows a typical axial field profile of the magnet stacks for twt applications. A gyrotron is a class of highpower linearbeam vacuum tubes which generates millimeterwave electromagnetic waves by the cyclotron resonance of electrons in a strong magnetic field. Still vital after all these years, printed in the april 1998 issue of ieee spectrum magazine. The klystron was invented by the varian brothers in 1939, they are in our microwave hall of. Travelling wave tube twt is an electronic vacuum microwave device, which is used as a high power microwave amplifier, mainly in telecommunication purposes and radar systems.
Travelling wave tube is a cylindrical structure which contains an electron gun from a cathode tube. In a microwave tube mwt a beam of electrons is bunched in an interaction structure supporting electromagnetic waves, and subsequently the kinetic or potential energy of the electron bunch is converted into electromagnetic energy. Microwave devices with electronwave interaction 56. The plasma frequency reduction factors for the wave components of the fundamental. Microwave tubes electron tubes electronics textbook. The interior end walls of the collector are a pair of.
The focusing field is perpendicular to the accelerating electric field. Abstractlargesignal analysis is presented for analysing nonlinear beamwave interaction in a planar thz twt with a sheet electron beam. Beam and wave electronics in microwave tubes, book, 1960. The theory of beamtype microwave tubes is concerned with the interaction of a beam of drifting electrons either with stationary electric fields gap systems or traveling electromagnetic waves travelingwave tubes, and so forth. The equations describing the interaction processes have been formulated within the twodimensional linear theory and solved using the dispersionequation approach and the successive approximation. This book explains, both qualitatively and quantitatively, the effects governing the operation of microwave tubes used in telecommunications, including tubes in circuits, properties of resonant circuits, and delay lines used as tube elements. Coupled mode theory, electron beams, microwave tubes publisher princeton, n.
Electron beam collector for a microwave power tubepatent. Output power was as large as 7 kw, corresponding to a device efficiency of 19%. Different types of microwave tubes amplifier wireless. An electron gun that products a high density electron beam.
The collector that collects the spent electron beam. Convegno internazionale delle communicazioni, genova, 812 october 1964, vol. Beam and wave electronics in microwave tubes, hutter, rudolf g. For example, presently gan devices are available as commercial products in s, c, x, and ku bands, and newer. Linear and nonlinear electron beam heating of magnetized. Excitation of electromagnetic waves by an axial electron. This phenomenon of cerenkov emission is the basis of all traveling wave tubes. Electromagnetic theory and applications in beamwave electronics by b n basu all. Microwave linear beam tubes microwave linear beam tubes mcqs. Pdf recent progress in the development of plasmafilled. In fact the efficiency of the energy transfer of an electron beam into the energy of a microwave signal can be estimated up. The effect of space charge on the interaction between an electron beam and an electromagnetic wave in a longitudinal magnetic field has been considered. Microwave tubes mwts continue to be important despite competitive. Review of the highpower vacuum tube microwave sources.
Introduction the advent of electron tubes in the 1920s was a remarkable. Pdf tapered tube, microsecond electron beam gyrotron. Microwave radiation is used in electron paramagnetic resonance epr or esr spectroscopy. Coherent microwave radiation is generated in and transmitted through a waveguidedrift tube by means of an injected relativistic electron beam the parameters of which, in combination with the waveguidedrift tube geometry and dimensions effect a virtual cathode oscillation condition within the waveguidedrift tube. Traveling wave tube twt, extended interaction oscillatoreio crossedfield or m type tubes. Tuning by varying the electron beam voltage was effective over a smaller frequency range. Microwave video lecture briefly describes the various important topics that you need to know for various exams like bsnl tta. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical engineers russell and sigurd varian, which is used as an amplifier for high radio frequencies, from uhf up into the microwave range. Linear beam tubes are often called otype the designation originated in france. Microwave tubes may seem old school for college kids. Design and simulation of electron gun for a multibeam klystron. Decreasing the volume of a cavity causes its resonant frequency to. Amplifiers based on the effects of resistance resistive amplifiers 60.
Technology under the innovative microwave vacuum electronics multidis ciplinary university. The electron gun emits an electron beam, and the microwave is amplified by the interaction of the slow wave structure, and the collector is used to absorb the. Tuning of the device is accomplished by manipulation of the. Twts seem to be an alternative and a more reliable solution than semiconductor devices when building high power and high frequency applications.
The performance is limited chiefly by the velocity spread in the spiraling electron beam, and once this can be brought under control, highpower generation of millimeter waves appears quite feasible with this type of device. Microwave part1 microwave tubes, magnetrons,transfer. Klystrons are the most efficient of linear beam microwave tubes. Microwave linear beam tubes mcqsnotesiqs mcqseries. Symons of litton electron devices division in his informative paper, tubes. Beamwave interaction in periodic and quasiperiodic structures. An axial electron beam passing through a slow wave structure is unstable to an electromagnetic perturbation whose phase velocity equals the velocity of the beam. Once again, cavity resonators are used as microwavefrequency tank circuits, extracting energy.
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