The travelling wave tube is a new sort of tube which displayed considerable promise as a board band amplifier proposed by pierce and others in 1946. The principle of operation of a twt is strikingly simple. By eliminating the need for long waveguide runs, transmit power is optimized and rf losses are reduced. An established technology area, the use of tubes remains essential in the field today for highpower applications. Travelingwave tube definition is an electron tube used for the generation of microwave frequency radiation or for amplification at ultrahigh frequencies whose operation depends on the interaction of a beam of electrons with an electromagnetic wave. Traveling wave tube a twt is capable of gains from 40 to 70 db with bandwidths exceeding two octaves. The highharmonic gyrotravelingwave tube gyrotwt is a highpower 1kw or more millimeter wave amplifier based on the synchronous interaction of a beam of largeorbit axisencircling electrons with a highorder cylindrical waveguide mode. Typical units duplicated in this way are the lownoise amplifier and the power amplifier. In a travelingwave tube the kinetic energy of electrons is transferred to the power of an electromagnetic wave rfsignal. Traveling wave tube an overview sciencedirect topics. The traveling wave tube inside hp 493a is radioactive. Difference between travelling wave tube twt and klystron. The latter originally used a traveling wave tube twt which had a limited life and required a highvoltage power supply. Offers detailed discussions of operating principles of helix and coupledcavity traveling wave tubes, descriptions of rf interactions of electrons with electric fields, and the basic theories of electron bunching and traveling wave interactions.
Nonlinear analysis of beamwave interaction in a planar. Mar 27, 2020 the primary purpose of the helix in a traveling wave tube is to a. The travelingwave tube the travelingwave tube twt is a highgain, lownoise, widebandwidth microwave amplifier. Principles of traveling wave tubes artech house radar. Helix studies as mentioned in the last progress report, a largescale model of the helix used in the travelingwave tube was constructed. Travelling wave tube basics, working and applications twt. For these purposes the device uses the interaction between. Other articles where travelingwave tube is discussed. In case of twt the interacting space is extended for the total length of the tube so that bunching takes place continuously. Traveling wave tubes an overview sciencedirect topics. The traveling wave tube amplifier twta together with the klystron are known as linearbeam types of microwave devices. It consists of a large number of coupled actually, overcoupled cavities and is reminiscent of a klystron with a very large number of intermediate cavities. The most important parameter for the use of the traveling wave tube as a preamplifier in radar receivers is the noise figure of the traveling wave tube.
On the evaluation of pierce parameters c and q in a. Twt as amplifier the travelling wave tube is an amplifier which makes use of a distributed interaction between an electron beam and travelling wave. The main elements of a travelingwave tube twt are 1 an electron gun, 2 a focusing structure that keeps the electrons in a linear path, 3 an rf circuit that causes rf. The department of defense dod uses microwave power tubes in land, sea, air, and space applications. The traveling wave tube can be used as a medium or high power microwave, amplifier. A twt is capable of gains from 40 to 70 db with bandwidths exceeding two octaves. Principles of traveling wave tubes artech house radar library.
Helix twt in which the radio waves interact with the electron beam while tr. Traveling wave tube development for a serrodyne reentrant amplifier abstract program objectives were to study serrodyne techniques and determine twt characteristics to incorporate in serrodyne reentrant amplifiers. Wider bandwidth property of travelingwave tubes twts is continuously pursued to satisfy the increased data rates and multiple channels in modern communications. Among the common applications of vacuum tubes are amplification of a weak current, rectification of an alternating current ac to direct current dc, generation of oscillating radiofrequency rf. A vacuum tube whose operation was based on the interaction between an electron flux and a traveling wave was first proposed and patented by the american engineer a. Solid state amplifiers sspa used mostly at sband also exhibit performance characteristics similar to twtas. Farouk mechanical engineering and mechanics department drexel university philadelphia, pa 19104 abstract a low cost travelingwave pulse tube refrigerator was designed, built, and successfully operated. Professionals find coverage of all major tube classifications, including klystrons, traveling wave tubes twts, magnetrons, cross field amplifiers, and gyrotrons. Antennamounted traveling wave tube amplifiers twtas. Design, construction and operation of a travelingwave pulse. Travelling wave tube amplifiers twtas for space applications.
The heated cathode at one end of the tube produces a beam of electrons and is attracted to the collector at the other end of the tube. Traveling wave tube definition is an electron tube used for the generation of microwave frequency radiation or for amplification at ultrahigh frequencies whose operation depends on the interaction of a beam of electrons with an electromagnetic wave. Electron tube, also called vacuum tube, device usually consisting of a sealed glass or metalceramic enclosure that is used in electronic circuitry to control a flow of electrons. A metal casing is necessary to ensure environmental electromagnetic field does not interfere with the operation of the tube as twt utilizes. A travelingwave tube twt is a specialized vacuum tube used in wireless communications, especially in satellite systems. Hoeff in 1936, and the first travelingwave tube was built by the american scientist r. Travelingwave tube definition of travelingwave tube by. When the wave on the axial electric field is at positive antinode, the electron from the electron beam moves in the opposite direction. Mcq in microwave tubes and circuits from the book electronic communication systems by george kennedy.
A travelingwave tube or travelingwave tube amplifier is a specialized vacuum tube that is used in electronics to amplify radio frequency signals in the microwave range. The electrons of the beam are surrounded by an rf wave. Xicoms antennamounted twtas are known worldwide for their reliable operation and long life. High power traveling wave tube amplifier and power supply. Operation of travelling wave tube the anode plates, when at zero potential, which means when the axial electric field is at a node, the electron beam velocity remains unaffected. Principles of traveling wave tubes artech house radar library a. Currently, we are looking into the possibility of a pulsed lowduty test of this device as a proof of principle.
The microwave power tube industry is one of many defense related industries that have been affected by this new environment. Therefore, this discussion applies to both sspa and twtas. The curve that shows the amplitude of the traveling wave at each point along the basilar membrane is called its envelope. The twt, because of its construction and working principle has enormous bandwidths and low noise.
Among the common applications of vacuum tubes are amplification of a weak current, rectification of an alternating current ac to direct. Electron tube, device usually consisting of a sealed glass or metalceramic enclosure that is used in electronic circuitry to control a flow of electrons. Evaluation of commercial traveling wave tubes for application in direct rf to rf transponders by i. Instruments for industry, t series twt amplifiers provide outstanding rf performance. Travelling wave tube is a cylindrical structure which contains an electron gun from a cathode tube.
Travelingwave tubes high voltage normal operating voltages are deadly. This page was split from our microwave tube page and we added some content and photos thanks to terry cisco. Traveling wave tube working fundamentals operations. The envelope has a positive and a negative side, but we generally only talk about the positive half because that. Additionally, the department of energy doe uses large, highpower klystron. The da consists of a pair of transmission lines with characteristic impedances of z 0 independently connecting the inputs and outputs of. Industrial assessment of the microwave power tube industry. The series a600 traveling wave tube twt amplifiers are used to linearly amplify microwave signals.
These are generally used to amplify microwave signals over broad bandwidths. A traveling wave tube twt is a specialized vacuum tube used in wireless communications, especially in satellite systems. The twt belongs to a category of linear beam tubes, such as the klystron, in which the radio wave is amplified by. In this video, i have explained travelling wave tube with following topics. A suitable structure for highpower andor highfrequency operation is the coupledcavity circuit, used by the traveling wave tube working of figure 1120. Helix studies as mentioned in the last progress report, a largescale model of the helix used in the traveling wave tube was constructed. Abstractlargesignal analysis is presented for analysing nonlinear beamwave interaction in a planar thz twt with a sheet electron beam.
The main benefits of traveling wave tube twt is wide bandwidth of operation and can generate hundreds and even thousands of watts. Investigations included the upper limit of serrodyning, optimum modulation methods and the. The culmination of the authorocos 50 years of industry experience, this authoritative resource offers you a thorough understanding of. The electrons are decelerated and the electromagnetic field gets stronger. Practical travelling wave tube amplifiers twtas have applications in both receiver and transmitter systems, and come in all shapes and sizes, but they all consist of three basic partsthe tube, the tube mount which includes the beam focussing magnets and the power supply. The travelling wave tube is an amplifier which makes use of a distributed interaction between an electron beam and travelling wave. Reinaldo perez, in wireless communications design handbook, 1998. Trans impedance increases indicated in figure input interaction interception klystron magnetic field magnetic flux metal microwave tube modulation mtbf noise figure occurs operation oscillations perveance phase velocity plot position potential minimum predicted pressure proc produced pump. 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. Travelingwave tubetravelingwave tube is an electric vacuum device, intended for generation and amplification of microwave oscillations. As illustrated here, an electron beam is emitted from the cathode and accelerated toward the collector at the opposite end of the device. This determines the sensitivity of the receiver and thus the maximum range of the radar. In this paper, the coalescedmode operation instead of the general singlemode operation for the double staggered grating waveguide dsgw slowwave structure sws is proposed to.
Traveling wave tube development i for a serrodyne reentrant. The operation of the da can perhaps be most easily understood when explained in terms of the traveling wave tube amplifier twta. It can then be energized and switched into operation, so extending the satellites life. Rf input is sent to one end of the helix and the output is drawn from the other end of the helix.
Dec 10, 2015 ultrawideband coalescedmode operation for a sheetbeam traveling wave tube abstract. It is capable of gains greater than 40 db with bandwidths exceeding an octave. Traveling wave tube amplifiers are widely used in satellite applications to provide signal power amplification at high frequencies. Travelling wave tube operation in order to design a helixtype traveling wave tube amplifier twta, it is necessary to understand the operating physics of a travelling wave tube twt. A traveling wave tube twt, pronounced twit or traveling wave tube amplifier twta, pronounced tweeta is a specialized vacuum tube that is used in electronics to amplify radio frequency rf signals in the microwave range. Hoeff in 1936, and the first traveling wave tube was built by the american scientist r. Abstractlargesignal analysis is presented for analysing nonlinear beam wave interaction in a planar thz twt with a sheet electron beam. Twts can also be used as both continuous and pulsed mode of operation.
Microwave tubes klystron,magnetron,twt traveling wave tube. A bandwidth of 1 octave is one in which the upper frequency is twice the lower frequency. Industrial assessment of the microwave power tube industry executive summary microwave power tubes are used in a variety of military, civil, and commercial applications. This practical reference serves as an excellent introduction for newcomers to the field and offers established tube engineers a comprehensive refresher. Wider bandwidth property of traveling wave tubes twts is continuously pursued to satisfy the increased data rates and multiple channels in modern communications. The rf signal wave injected at the input end of the helix travels down the helix wire at the speed of the light but the coiled shape causes the wave to travel a much greater distance than the electron beam. The operation of the da can perhaps be most easily understood when explained in terms of the travelingwave tube amplifier twta. In a traveling wave tube the kinetic energy of electrons is transferred to the power of an electromagnetic wave rfsignal. An electron beam device for generating microwaves, such as a travelling wave tube, usually consists of a beam source which is often a diode, an accelerating region and a wavebeam interaction region where the electromagnetic radiation is generated. Two common types of twt include the klystron and the magnetron. Operation of a largeorbit highharmonic gyrotraveling. A travelling wave tube twt is a specialized vacuum tube that is used in electronics to amplify radio frequency rf signals in the microwave range. This microwave tube is used as microwave rf power amplifier. Although there are various types of twt, two major categories are.
The da consists of a pair of transmission lines with characteristic impedances of z 0 independently connecting the inputs and outputs of several active devices. The equipment must be designed so the operator cannot come into contact with high voltages. Design, construction and operation of a travelingwave. The travelingwave tube can be used as a medium or high power microwave, amplifier.
Ultrawideband coalescedmode operation for a sheetbeam. Travelling wave tube an helix as interaction structure, where the electron beam interacts with the microwave signal to be amplified. On the evaluation of pierce parameters c and q in a traveling. Our t series twta traveling wave tube amplifier products are a mature design but incorporate the latest features with respect to control and monitoring. Design, construction and operation of a travelingwave pulse tube refrigerator s. The twt was invented by rudolf kompfner in 1942 in england, for this reason he appears in our microwave hall of fame. Klystrons, traveling wave tubes, magnetrons, crossedfield.
Traveling wave tube amplifiers twtas antennamounted twtas. Clay prillaman communications satellite research branch abstract a traveling wave tube twt finds application in communica tion satellite transponders where it is used to simultaneously am plify many signals over a broad spectral range. Travelingwave tube article about travelingwave tube by. Highvoltage circuits and terminals must be enclosed, and interlocking switch circuits must be maintained so they open the primary circuits of the power.
The dod uses microwave power tubes in a wide variety of system applications, and will continue to do so well into the next century. The primary purpose of the helix in a travelingwave tube is to. Two type of twtas, the helix for broadband applications and the coupled cavity for highpower applications are predominant. This chapter provides the basic description of the twta structure and its various components. Travelling wave tube amplifiers twtas for space applications bosch has provided twtas which satisfied requirements of nasa, esa, intelsat, inmarsat, european, asian and us commercial programs. The traveling wave tube the traveling wave tube twt is a highgain, lownoise, widebandwidth microwave amplifier. A wide variety of applications were covered by these twtas.