In this paper, we describe the first experimental manifestation of a high power microwave device utilizing a metallic slow wave structure metamateriallike fabricated using additive manufacturing. Principles of travelling wave tubes twts q electron gun supplies the electron beam q input and output couplers supply the rf signal q focusing magnets confines the electron beam to center q slow wave structure i. The greens function on a slow wave structure is cons tructed. Lewis research center cleveland, ohio june 1994 national aeronautics and space administration nasatmi06654 evaluation of. Fullwave analysis of the high frequency characteristics of. We analyzed artefactfree eeg traces from all epochs of n2 and n3 sleep referred to collectively as nrem sleep at the electrode positions depicted in. Giant amplification in degenerate band edge slowwave. The formulas of dispersion and interaction impedances of the hybrid modes are obtained by combining the helmholtz equation with the appropriate boundary conditions. The propagation characteristics of the crosstieoverlay slow wave structure are analyzed both analytically and experimentally. Eight male subjects age 2128 years were paid to participate in the study to which they each gave their informed consent. The antenna elements are formed from regularly bent wires. The greens function includes all radial modes, and for each radial mode, all space har monics. The new wave ring helical wrh slowwave structure for traveling wave tube amplifiers nasser panahi 0 s. Hfss and cstmws with slow wave structure with tip loss on support rods.
It also disrupted sleep and facilitated lightinduced wakening, establishing a role for slow wave oscillations in regulating sleep and sensory gating. Doublecorrugated rectangular waveguide slow wave structure for terahertz vacuum devices. Slowwave sleep sws, often referred to as deep sleep, consists of stage three of nonrapid eye movement sleep. Instead of using the lossy dielectric, the crosstieoverlay slow wave structure uses the periodic structure to create the slow wave mechanism. A new threelayer slow wave structure is proposed to demonstrate the design methodology. Oct 04, 2017 in this video, i have explained travelling wave tube with following topics.
Finally, a branchline coupler, evolved from this slow wave structure, is designed and tested. The results show significant size reduction as compared to the use of a normal microstrip line structure. It is a particular type of wave propagation described mostly in frequency domain. Gain enhancement in slowwave structures with degenerate. A planar sheathlike slow wave structure with rectangular geometry is considered for use in a traveling wave amplifier driven by a sheet electron beam. In this paper slow wave structures with some improved parameters and properties are introduced as. Analysis of some periodic structures of microwave tubes. Unambiguous determination of the wave impedance of slow wave structures. Evaluation of some slowwave vane structures for a miniature. A field analysis of a helix structure with a metal shield surrounded by a uniform cylindrical dielectric has been. Traveling wave tube working fundamentals operations. Thus a slow wave structure is a nonresonating device used to reduce the phase velocity of the em wave. Classical traveling wave tube ampli er model with its main components 1. This type of slow wave structure tends to be limited to frequencies below 100 ghz, above which ringbar and other structures may be employed.
The electron beam is received at the collector after it has passed through the slow wave structure. Sep 26, 2014 a model of a slow wave structure in the form of a ladder network of connected resonators with a transit channel filled with plasma is developed. The accelerated electron beam tends to diverge while moving through the slow wave structure sws due to space charge forces. The complete field theory is more exact than the coupled wave theory. Slow wave structures act to reduce the group velocity of a transmission line, or increase its group delay compared to a normal fastwave structure. Controlled coupling in reduced size slow wave structure antennas by dan handelsman and david jefferies introduction. The sheath like structure provides a lowdispersion operating mode and hence potential for broad. Initially, sws consisted of both stage 3, which has 2050 percent delta wave activity, and stage 4, which has more than 50 percent delta wave activity. Ghorannevis 0 0 plasma physics research center, science and research branch, islamic azad university, tehran, iran in this paper, the new slow wave structure called wave ring helix to enhance the power of the traveling wave tubes is introduced. Synthesis of slowwave structures based on capacitive. However, when there is intermittent or persistent focal slowing seen consistently over one head region, or persistent, unvarying, and unreactive focal or generalized slow wave activity in a vigilant adult patient, this slow wave activity should be considered pathologic and indicates corresponding focal or generalized cerebral dysfunction or both. Unambiguous determination of the wave impedance of slow. Distributed slowwave dynamics during sleep predict memory. Slow wave structure is a circuit or transmission path.
Slow wave structures integrated with ferromagnetic and. Pdf doublecorrugated rectangular waveguide slowwave. Jun 11, 2010 this article applies an explicit method to the fast structural design for the slow wave circuit of a 0. Field expressions and sheathhelix boundary conditions. Slow wave guiding structures have been extensively studied to reduce the circuit size 220. The stwt studied in this paper is a helix traveling wave tube. High power microwave source with a three dimensional.
Excitation of a slow wave structure msu college of engineering. Analysis of the electromagnetic waves in an overmoded finite. To valid the primary design, coldcircuit properties, such as dispersion and interaction impedance, were calculated by using both theoretical method and electromagnetic software cst mws simulation. Pdf analysis of a coupledcavity slow wave structure for a twt.
The spectral behaviour is periodical and closed form. When there is large divergence of the electron beam leading to interception by the slow wave structure, it results in the heating of the sws. The slow wave structure gives the twt its wide bandwidth. Determination of the interaction impedance of helix slow wave structures richard g. The antenna discussed here is called a zagi and an example is shown in figure 1. The feasibility of utilizing additive manufacturing as a technique for building these relatively complicated structures has thus been demonstrated. A theoretical model for calculation of the high frequency characteristics of the sine waveguide slow wave structure sws is proposed. A comparative study on different types of coplanar wave guide cpw slow wave structures sws has been demonstrated for the first time. Slow wave structure is a circuit or transmission path where the phase velocity is much less than the speed of the light.
Although use of a wide sheet beam promises high power, the large transverse dimension of the struc ture risks interaction. Studies on planar helical slowwave structures for traveling wave tube applications chua cier siang school of electrical and electronic engineering a thesis submitted to the nanyang technological university in partial fulfillment of the requirement for the degree of. Networkspecific synchronization of electrical slowwave. The emphases in this paper concentrate on the present state of study of four types of structures. Microwave slowwave structure and phase compensation. Genetically targeting the coincidence detector function of nmdars in r5, and thus the uncovered mechanism underlying synchronization, abolished networkspecific compound slow wave oscillations. A slow wave potential is a rhythmic electrophysiological event in the gastrointestinal tract. Slowwave structures are useful in shrinking electricallylong elements.
Othman,1 mehdi veysi,1 alexander figotin,2 and filippo capolino1 1department of electrical engineering and computer science, university of california, irvine, california 92697, usa 2department of mathematics, university of california, irvine, california 92697, usa. Giant amplification in degenerate band edge slow wave structures interacting with an electron beam mohamed a. The zagi controlled coupling in reduced size slowwave. Analysis of a coupledcavity slow wave structure for a twt. New slow wave structures for travelling wave tubes spiral. The coupledcavity slow wave structure is a stack of circular cavities, which are coupled to each other through their common wall. The new wavering helical wrh slowwave structure for. Electrodynamics and electron optics of slowwave comb. Metamaterialbased slow wave structures for travelling wave tubes. It is well known that the phase velocity of the em wave in the waveguide is larger than velocity of the light in vacuum. Selfphase modulation effects in 1d optical slowwave structures made of fabryperot cavities. Carter engineering department, lancaster university, lancaster la1 4yr, uk phone.
Operation is similar to that of a klystron, except that coupledcavity twts are designed with attenuation between the slow wave structure instead of a drift tube. The nonlinear response of the structure is investigated by a comparative analysis of several numerical methods. The normal conduction of slow waves is one of the key regulators of gastrointestinal motility. Determination of the electrodynamic characteristics of slow. Experimental analysis of millimeter wave coplanar waveguide slow wave structures on gaas ralph spickermann and nadir dagli, member, ieee abstract microwave coplanar waveguide slow wave struc tures suitable for use in traveling wave electrooptic modula tors were experimentally investigated to 40 ghz. The predominance of sws in the early part of the sleep episode was documented in several early studies.
The mechanism behind the slow wave propagation is to separately store the electric and magnetic energies as much as possible in the guided wave media. Analysis the helical slow wave structure under study fig. The model represents an eightterminal network, which is used to determine and calculate the electrodynamic characteristics. In order to reduce the velocity of the wave so that the electrons can get sufficient time to interact with wave, wave is passed through the slow wavestructure and thus the phase velocity of the wave is reduced. We compare the analytic solution of the frequency response on the slow wav e structure with that obtained from a particleincell code. An oscilloscope tube with helix slow wave structure was described by germeshausen et al. Gain enhancement in slow wave structures with degenerate band edges mohamed othman 1, mehdi veysi, alex figotin2, filippo capolino oct.
Pdf slowwave structuresbased method of measurements. Allmetal slow wave structures are being paid great attention because of their advantages, such as good heat dissipation, high power capacity, wide passband, good wholeness of structure and large size etc. K othman1, mehdi veysi1, alexander figotin2, and filippo capolino1a 1department of electrical engineering and computer science, university of california, irvine, ca 92697 usa. In principle a tape helix slow wave structure could be modelled using the method of moments in a manner similar to that described in section 3. Traditionally, the circularly wounded conducting wire, or helix, is used as the sws 1. In this video, i have explained travelling wave tube with following topics. Propagation through a slowwave structure electromagnetic. Slow wave structures wu major reference works wiley. A door knob type wave guide to coaxial adopter has been used for better heat dissipation. This new slowwave structure, loaded with a stub at the center of the uturn section, has higher interaction impedance and lower phase velocity. The results show that this mtm sws is very helpful to miniaturize the highpower vacuum electron devices and largely improve the output power and the electronic efficiency.
Contribution of the circadian pacemaker and the sleep. Optical slow wave structures andrea m elloni, francesco m orichetti and m ario m artinelli nonlinear processes are enhanced in slow wave structures that consist of a cascade of directly coupled optical resonators. Figure 1119 shows the exponential signal growth along the traveling wave tube, but it is not to. Application of gsmocso algorithm to slowwave structure. A helixlike slow wave structure is used for the electron wave beam interaction and a collector at the end of the tube stops the electron beam after it has travelled through the tube. Slow wave structures are useful in shrinking electricallylong elements. Get a printable copy pdf file of the complete article 1. The analysis of helical structure in the slow wave regime, revisited in the present part i, kept outside its purview the analysis of axially periodic discloaded circular waveguide of a gyrotwt in the fast wave regime, which will be taken up in part ii of the paper to follow. The waveguide consists of a composite medium with three. It is shown that the introduction of a plasma enables the operating band of the slow wave structure to be extended and also.
Comparison of two slow wave structure antennas 1sakshi jindal, 2shivam singhal, 3saurabh vishnoi, 4brajlata chauhan, 5sandipvijay 1,2,3,4,5department of electronics and communication, dit university, dehradun abstract. Slow waves when the wave propagates along the device axis with phase velocity. In the slow wave structure, the electromagnetic wave velocity is kept synchronized with the electron beam velocity to generate interaction and energy exchange between them. A wideband twt universally uses helical slowwave structure sws as the interaction structure due to its nonresonant behaviour and consequent wide. Allmetal metamaterial slowwave structure for highpower.
Pdf a novel electromagnetic measurement method is described from the physical point of view. The rectangular supports deviating from the simple wedge geometry and the metal segments make the structure. A few of the properties of electromagnetic waves in periodic structures are considered, with some discussion of propagation in openboundary structures. Travelling wave tube basics, working and applications twt.
Twodimensional hybrid simulations of filamentary structures and kinetic slow waves downstream of a quasiparallel shock yufei hao 1,2,3, quanming lu1,3, xinliang gao1,3, huanyu wang1,3, dejin wu4, shui wang1,3 1cas key laboratory of geospace environment, department of geophysics and planetary science, university of science and technology of china, hefei 230026. Possible slow wave structures for travelling wave tubes travelling wave tube with periodic slow wave liner dielectricferrite corrugations metal corrugations concentric metallic rings coupled transmission lines on dielectric limited wave slow down good for relativistic ebeams, v e c cherenkov radiation in periodic media 1 2 electron. Evaluation of some slow wave vane structures for a miniature traveling wave tube at 30 ghz frank kavanagh analex corporation brook park, ohio ben ebihara, thomas m. Photonic band gap corrugated slow wave structure for thz. The nonlinear response of the structure is investigated by a comparative analysis of several numerical methods operating either in time or frequencydomain. In this thesis, a planar sheathlike slow wave structure with rectangular geometry is studied and considered for use in a twta driven by a sheet electron beam. The more the group velocity of light is reduced, the higher the structureinduced enhancement of nonlinearities and wave interactions. Planar slow wave structure with parasitic mode control by long bao nguyen dissertation submitted to the faculty of the graduate school of the university of maryland, college park in partial ful llment. If slow wave structures are closed to free space, they do not behave as antennas i. A resistive coating was placed on the outside of the dielectric tube in structure i while structure ii had a resistive coating on the inside of the dielectric tube. Pdf planar slowwave structure with parasitic mode control. Schematic diagram of a spatially periodic slow wave structure sws showing the directions of forwardly propagating wave f and backwardly propagating wave b. In this paper slow wave structures with some improved parameters and properties are introduced as the solution to the above mentioned.
Slow wave structures act to reduce the group velocity of a transmission line, or increase its group delay compared to a normal fast wave structure. Oct 12, 2015 for example, an sband slow wave structure sws based on the allmetal mtms has been studied by both simulation and experiment. Slow wave structure how is slow wave structure abbreviated. In twt, sinusoidal corrugated slow wave structure sws is used to reduce the phase velocity of the electromagnetic wave to synchronize it with the electron beam velocity, so that a strong interac. These structures are used to reduce the wave velocity in a certain direction so that the slow moving electrons of electron beam can interact with the fast moving electromagnetic wave. Pdf the new wavering helical wrh slowwave structure for. Evaluation of some slowwave vane structures for a miniature travelingwave tube at 30 ghz frank kavanagh analex corporation brook park, ohio ben ebihara, thomas m. This paper describes an approach of designing a coupledcavity slow wave structure ccsws for a high power traveling wave tube twt using hfss code, which is a 3d high frequency.
Dispersion and growthrate characteristics of a sinusoidally. Among these structures, this paper focuses on the microstrip slow wave structures where the. Design considerations of miniaturized least dispersive. Pdf in this paper, the new slowwave structure called wavering helix to enhance the power of the traveling wave tubes is introduced.