Design of Undepressed Collector for Ka-band Gyro-TWT Amplifier

Design of Undepressed Collector for Ka-band Gyro-TWT Amplifier | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Design of Undepressed Collector for Ka-band Gyro-TWT Amplifier Mukesh Kumar Alaria, SK ghosh This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8072976/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The design and analysis of an undepressed collector for Ka-band Gyro-TWT have been described in this paper. Initially, trajectory analysis has been carried out after preliminary design of the un-depressed collector. EGUN code and ANSYS software are used for trajectory and mechanical analysis respectively. Thermal design has also been carried out for finalization of collector geometry such as collector thickness, collector length and the estimations and optimizations of temperatures on the both inner and outer collector surfaces with the reasonable flow of coolant around the collector. The uniform electron beam spread of 300 mm has been achieved for wall loss of 0.43 kW/ cm 2 for the collector diameter and length equal to 70 mm and 500 mm respectively. The maximum temperature has been obtained on the collector is 220 o C. Gyro traveling wave tube (Gyro-TWT) Thermal analysis Undepressed Dissipation Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Gyro-TWTs are potential candidates in millimeter-wave communication system and high power radar systems, under the design and development in various laboratories [ 1 ]-[ 2 ]. The collector is the very important component used for the final collection of the electron beam in a Gyro-TWT. The collector plays a significant role in Gyro-TWT as a power capacity holder of the device. The electron beam is generated from the magnetron injection gun and transfers some of its energy to RF in the interaction structure and then proceeds further in the device [ 3 ]-[ 4 ]. Obviously, a component is needed to collect all the electron beam after beam wave interaction and that component is normally called as an electron beam collector or simply collector. The beam collected on the collector is called as the spent electron beam. Although the electron beam loses some of its energy to RF power, however, a sufficient kinetic energy remains in the spent electron beam depending upon the efficiency of the device [ 5 ]. The collector is supposed to handle a large power coming from the spent electron beam as due to conversion of the kinetic energy electron beam remaining in the spent beam into the thermal energy leading to the increase of the temperature of the collector. Thus the collector design should be such that there is not much rise in the temperature of the collector to avoid the melting or even softening of the collector material. Normally, collector is supposed to be cooled, particularly, in a high power Gyro-devices to provide the smooth flow of heat flux from the inside surface to outside surface of the collector [ 6 ]-[ 7 ]. Thus, normally, oxygen free high conductivity (OFHC) copper is used as the collector material due to its high thermal conductivity capability along with other features like vacuum compatibility, ease of availability, etc. Collectors are normally of two types one is un-depressed collector and second is depressed collector, respectively. In the un-depressed collector the collector and the device body (control anode) are at the same potentials while at different potentials in the depressed collector. In a Gyro-TWT, the electron beam profile is designed to strike on a large extended length or surface of a collector so that there is no back reflection towards the interaction structure from the collector as well as there is no bombardment of electron beam on the RF window [ 8 ]. Design of electron beam spread is made is in such way that wall loading for collector surface should not be more 1.0 kW/cm 2 . Figure 1 shows the schematic view of the Gyro-TWT. Electron beam experiences a reduced magnetic field after the beam-wave interaction and thus its larmor radius is increased in the collector and thus having a natural tendency to strike on the collector. However, it is also required to have a magnetic system around the collector too for the proper electron beam spread for the reduced power dissipation on the collector surface [ 9 ]. Cooling is done normally by conventional cooling where water is circulated around the collector to transfer the heat through its heat transfer capability. The proper electron beam spread is achieved with the optimization of collector and surrounding magnet parameters through an electron beam dynamics tool [ 10 ]. Similarly, the collector thermal behavior is achieved through the optimization of collector thickness and cooling system parameters with the help of a thermal analysis tool. Therefore, the collector system needs two design aspects related to electrical design and thermal design, respectively. The collector will influence the distribution of dissipated power, we proposed a curved profile collector to make the dissipated power more uniformly. This design has increase power capacity and reduced the maximum temperature of collector. Design of Undepressed Collector In this paper design methodology of undepressed collector for a gyro-TWT has been described. The collector is a waveguide to collect spent electron beam and dissipated their energy on the collector as heat and dissipated as heat without any attempt to recover energy from it through voltage depression. EGUN code has been used for the design of the un-depressed collector for Gyro-TWT. The length and radius of the collector for Ka-band Gyro-TWT have been optimized using EGUN simulation and discussed. The analyses consider effective and the uniform electron beam spreading as well as the wall loading within the limits [ 11 ]. To avoid the melting of the collector surface, it requires thermal and structural analysis of the collector. The overall performance of the device depends upon the power dissipation process of the collector. The electron beam profile is designed to strike on a large extended length or surface around middle portion of a collector so that there is no back reflection towards the interaction structure from the collector as well as there is no bombardment of electron beam on the RF window. Design of electron beam spread is made is in such way that the wall loading for collector surface should not be more 1.0 kW/cm 2 . Electron beam analysis is needed for the electrical design of collector, which helps in getting the maximum electron beam spread. This is carried out with the help of a commercially available and widely used the electron beam analysis code EGUN [ 12 ]. Before the analysis, some design goals have been set up for the optimized collector design. These goals may be defined as collector length should be such that electron beam should not touch the collector end, electron beam spread should be maximum and should be around the center of the collector, magnetic field value around the collector should be as low as possible, coolant temperature should not be more than 50 degree centigrade etc. The analysis of electron beam collector helps to optimize the collector dimensions and to achieve the maximum electron velocity spread on collector surface through the magnetic field optimization. It is found that the magnetic field plays a very important role in the optimization of the length and the radius of the collector. Electron beam analysis is carried out with the help of EGUN code to study the beam spread over the collector surface. Table 1 shows the electron spent beam parameters of collector for Ka-band Gyro-TWT. The electron beam simulation is carried out using 30 beamlets with the real energy distribution of the beam. The beamlets represent the beam power equivalent to the 550 kW. Initially, the electron beam energy is 650 kW generating from electron beam source and after the beam wave interaction 100 kW RF power is taken out of the window. The rest 550 kW power is remained with the electron beam and needs to be dissipated on the inner surface of the collector. Figure 2 shows the spent beam profile at collector surface without the use of any additional magnetic coil around the collector. The dimensions of collector has been optimized as length equal to 500 mm and radius equal to 35.0 mm, thickness is 20.0 mm after lot of iterations to get the best possible landing of the spent electron beam. The iterations is carried out to get best, that is, the maximum uniform electron beam spread in the middle part of the collector. It is found that a two layer system of magnet systems yields the optimized result of the electron beam spread of 300 mm. Table 1 Design parameters of Collector for Ka-band Gyro-TWT S.N Parameters Values 1. Beam Voltage 65 kV 2. Beam Current 10 A 3. Velocity Ratio 1.2 4. Larmor Radius 0.4 mm 5. Beam Radius 4.2 mm 6. Wall loss 0.51 kW/cm 2 7. Dissipation Power 0.43 kW/cm 2 8. Collection Area 1231 cm 2 Thermal Design of Collector A system is heated under the influence of some sort of heat flux. This is also true for the collector. The high energetic spent electron beams are incident on the collector surface and thus the temperature of the collector is increased. It is always preferable to maintain the temperature of the collector within the limit so that there is no thermal stress on the collector body during the operation of the device. The thermal behavior is estimated through thermal analysis. The ANSYS code has been used for the thermal analysis [ 13 ]. Two types of thermal analysis can be performed, such as steady state analysis and transient analysis, respectively. The equilibrium temperature distribution within a structure is estimated through a steady state thermal analysis to determine steady heat flow rates. A transient thermal analysis is used to determine the temperature distribution in a structure. Heat load can be applied on the wall surface in the form of heat flux or heat generation rate or specified temperature in each of the thermal analyses [ 14 ]. The thermal design of collector for Gyro-TWT is carried out to estimate the safe collector temperature. On the basis of the simulation, the thickness of the collector, collector shape and the water flow rate have been finalized. Figure 3 shows the 3D view of the collector geometry for Ka-band Gyro-TWT. In the cooling system water is used as coolant for the thermal study. The thermal and mechanical properties of water and OFHC copper are given in Table 2 and Table 3 respectively [ 15 ]. After meshing in the collector geometry, the material properties are applied. After that, the loads and the boundary conditions are applied. The power density of 300 mm spread is 0.43 kW/cm 2 . However, in the thermal analysis, for the sake of convenience, the average wall loss is applied on the collector surface along the length or surface equivalent to the electron beam spread. The basic property of water like density, viscosity, thermal conductivity, etc. change with the rise in temperature and in the thermal analysis, the changed values of these parameters are used. After finding the optimized heat film coefficient, the hydraulic diameter is found for a given coolant flow rate through. In this respect, a typical plot has been created between water flow rate and hydraulic diameter for various values of heat film coefficients [ 16 ]. It is very clear that the hydraulic diameter increases with increase in the water flow rate at a given value of heat film coefficient whereas hydraulic diameter decreases with increase of heat film coefficient at a given water flow rate. However, the collector surface temperatures decrease with the increase of the heat film-coefficient. Two cases of power dissipations have been studied, such as, 550 kW dissipated spent electron beam power when 100 kW RF power is generated and total 650 kW spent electron beam power when no RF power is generated. The studies have been carried for various inlet water temperatures such as 288K − 293K and hydraulic diameters ranging from 4.5- 5.0 mm diameter. It is always desired to achieve the inner collector surface temperature around or less than 473 K which is easily obtained in the simulations through these simulated results. The maximum temperature on the surface of collector is 220 o C.The typical thermal analysis results for both situations related to 550 kW and 650 kW power dissipations have been carried out. Figure 5 showing the temperatures of inner and outer surfaces of the collector with the 550 kW and 650 kW power dissipations for different water flow rates. From these simulated results, it is very clear that in all the cases the inner and outer temperature rise time becomes constant after 2–3 sec. and decreases with increase in water flow rate. The maximum inner and outer temperature variation of depressed collector with heat film coefficient (h) shown in Fig. 6 . The dissipated power is distributed in the axial range of 300–1000 mm and maximum dissipated power is 0.43 kW/cm 2 . The analytical dissipated power with axial distance of collector shown in the Fig. 7 . The collecting profile is a rectangular which is uniform. In this paper thermal analysis of the undepressed collector for ka-band gyro-TWT has also been carried out using ANSYS software. The thermal analysis of the collector, during extreme case of operation has been carried out. A transient thermal analysis has been used to determine the temperature distribution as a function of time. Table 2 Properties of water as a coolant for the cooling system Parameters Units Values Density Kg/m 3 988.21 Viscosity NS /m 3 0.855x10 -3 Conductivity W/m K 0.58 Table 3 Thermal and mechanical properties of OFHC copper Parameters Units Values Density Kg/m 3 8960 Thermal Conductivity W/m K 334 Emissivity - 0.4 Specific Heat J/(kg.K) 385 Young’s Modulus GPa 110 Poisson’s Ratio - 0.33 Thermal expansion Coefficient K 17E -6 Conclusions In conclusion, it has been established that available collector design is capable of handling the thermal and mechanical loading in a 100 kW power. The design of Un-depressed collector for Ka-band Gyro-TWT is presented in this paper. The initial estimation of collector dimensions length and diameter have been estimated with the help of analytical expressions subjected to the technical limit of wall loss. The trajectory, thermal and structural analysis is carried out for the design of Un-depressed collector. The simulated results have been optimized the collector length 500 mm and collector radius 35 mm with the minimum heat loading of 0.43 kW/cm 2 for uniform electron beam spread. The maximum temperature is 220 0 C on the inner surface of the collector and 47 0 C on the edge of the collector outer surface at optimized 3x10 5 W/m 2 .K heat film coefficient (h). Declarations Acknowledgement This work was carried out under a SERB-DST sponsored project. References Nusinovich GS (2004) Introduction to the physics of Gyroton, Maryland, JHU, USA Chu KR (2002) Overview of research on the Gyrotron traveling wave amplifier. IEEE Trans Plasma Sci 30(3):903–908 Edgecombe CJ (1993) Gyrotron Oscillators: Their principles and practice. London (UK) Taylor & Francis Ltd. Gilmour AS Jr., Klystrons TW, Tubes (2011) Magnetrons, Crossed-Field Amplifiers, and Gyrotrons. Artech House, Boston, MA, USA Du CH, Liu PK (Oct 2009) A Lossy Dielectric-Ring Loaded Waveguide with Suppressed Periodicity for Gyro-TWTs Applications. IEEE Trans Electron Devices 56:2335–2342 Chu KR, Barnett LR, Lau WK, Chang LH, Kou CS (1990) Recent developments in millimeter wave Gyro-TWT research at NTHU. Int Electron Dev Meeting Tech Dig, pp. 699–702 Ran Y, Di Wang H, Li M, Mu Yuanyuan Lian, and Yong Luo Design of Collectors for High Average/Continuous-Wave Power Gyro-Devices. IEEE Trans Electron Devices, 66, 6, pp.1512–1518, March 2019. Du CH, Liu PK (2009) Stability study of a gyrotron-traveling-wave amplifier based on a lossy dielectric-loaded mode-selective circuit. Phys Plasmas, 16 Tang Y, Luo Y, Xu Y (November 2014) Design of a Novel Dual-Band Gyro-TWT. IEEE Trans Electron Devices 61:3858–3863 Liu B et al (2013) Experimental study of a Q-band gyro-TWT, in Proc. IEEE 14th Int. Vac. Electron. Conf. (IVEC) May Barnett LR, Lau YY, Chu KR et al (1981) An Experimental Wideband Gyrotron Traveling-Wave Amplifier. IEEE Trans Electron Devices 28:872–875 Hermannsfeldt EGUN (1979) W.B., Stanford Linear Accelerator Center, Stanford University Report SLAC-226 User Manual Ansys- (2019) Ansys Mechanical Finite Element Analysis Software, Canonsburg, PA, USA, 2019 Incropera FP, DeWitt DP, Bergman TL, Lavine AS (2007) Introduction to heat transfer, (5th Ed), John Wiley & Sons, ISBN: 978-0-471-45727-5 Kumar A, Goswami UK, Poonia S, Singh U, Kumar N, Alaria MK, A.Bera and, Sinha AK (2011) Integrated design of undepressed collector for low power gyrotron. J Infrared Millim Terahertz Waves 32(6):733–741 Goswami UK, Singh U, Kumar N, Sahu NK, Kumar A (2013) .Yadav,R.L dua and A.K.Sinha Development of cooling system for gyrotron collector. J Fusion Energy 32(4):518–522 Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8072976","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":542398694,"identity":"a8d59e13-47d9-4f77-bb10-770791d99cda","order_by":0,"name":"Mukesh Kumar 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2","display":"","copyAsset":false,"role":"figure","size":206539,"visible":true,"origin":"","legend":"\u003cp\u003eSpent beam profile at collector surface\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8072976/v1/6d297ebe01188afaed523efc.png"},{"id":95765385,"identity":"f7129e5f-7a04-4fe4-9b4b-734fb38e6acc","added_by":"auto","created_at":"2025-11-12 19:35:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":78675,"visible":true,"origin":"","legend":"\u003cp\u003e3D view of collector geometry for Ka-band Gyro-TWT\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8072976/v1/2a6548258b0e2e3e10d494bc.png"},{"id":95802554,"identity":"c3db1373-b098-4bfa-87ff-32e60344800b","added_by":"auto","created_at":"2025-11-13 08:27:51","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":187420,"visible":true,"origin":"","legend":"\u003cp\u003eSimulated temperature distribution on the collector\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8072976/v1/9ba323c507bee58d0487a35d.png"},{"id":95765387,"identity":"ce01e006-f868-4f4b-b7ca-7e5e421c1e53","added_by":"auto","created_at":"2025-11-12 19:35:21","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":86326,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of temperature with water flow rate\u003cstrong\u003e \u003c/strong\u003efor\u003cstrong\u003e \u003c/strong\u003edifferent power dissipation\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8072976/v1/c1aa524a343ba5c22d4e4308.png"},{"id":95801782,"identity":"14fd1f54-feab-406e-8edb-ccc94aa1b2cb","added_by":"auto","created_at":"2025-11-13 08:26:08","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":76698,"visible":true,"origin":"","legend":"\u003cp\u003eMaximum outer and inner temperature variation with heat film coefficient (h)\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8072976/v1/0c2d42aabe11e35d477449e3.png"},{"id":95802342,"identity":"c5f4eac4-2258-4605-a482-781f5f8af7b9","added_by":"auto","created_at":"2025-11-13 08:27:29","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":43647,"visible":true,"origin":"","legend":"\u003cp\u003eDissipated power with axial distance of collector\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8072976/v1/d00a150cbdefa100ba54743d.png"},{"id":95805485,"identity":"f2595b35-4b2d-4a2d-92f3-f9cfd1620049","added_by":"auto","created_at":"2025-11-13 08:41:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1175602,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8072976/v1/6a6c0fd6-f656-46d8-b465-9aa4ec2beaa2.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eDesign of Undepressed Collector for Ka-band Gyro-TWT Amplifier\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eGyro-TWTs are potential candidates in millimeter-wave communication system and high power radar systems, under the design and development in various laboratories [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]-[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The collector is the very important component used for the final collection of the electron beam in a Gyro-TWT. The collector plays a significant role in Gyro-TWT as a power capacity holder of the device. The electron beam is generated from the magnetron injection gun and transfers some of its energy to RF in the interaction structure and then proceeds further in the device [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]-[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Obviously, a component is needed to collect all the electron beam after beam wave interaction and that component is normally called as an electron beam collector or simply collector. The beam collected on the collector is called as the spent electron beam. Although the electron beam loses some of its energy to RF power, however, a sufficient kinetic energy remains in the spent electron beam depending upon the efficiency of the device [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The collector is supposed to handle a large power\u003c/p\u003e\u003cp\u003ecoming from the spent electron beam as due to conversion of the kinetic energy electron beam remaining in the spent beam into the thermal energy leading to the increase of the temperature of the collector. Thus the collector design should be such that there is not much rise in the temperature of the collector to avoid the melting or even softening of the collector material. Normally, collector is supposed to be cooled, particularly, in a high power Gyro-devices to provide the smooth flow of heat flux from the inside surface to outside surface of the collector [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]-[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Thus, normally, oxygen free high conductivity (OFHC) copper is used as the collector material due to its high thermal conductivity capability along with other features like vacuum compatibility, ease of availability, etc. Collectors are normally of two types one is un-depressed collector and second is depressed collector, respectively. In the un-depressed collector the collector and the device body (control anode) are at the same potentials while at different potentials in the depressed collector. In a Gyro-TWT, the electron beam profile is designed to strike on a large extended length or surface of a collector so that there is no back reflection towards the interaction structure from the collector as well as there is no bombardment of electron beam on the RF window [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Design of electron beam spread is made is in such way that wall loading for collector surface should not be more 1.0 kW/cm\u003csup\u003e2\u003c/sup\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the schematic view of the Gyro-TWT. Electron beam experiences a reduced magnetic field after the beam-wave interaction and thus its larmor radius is increased in the collector and thus having a natural tendency to strike on the collector. However, it is also required to have a magnetic system around the collector too for the proper electron beam spread for the reduced power dissipation on the collector surface [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Cooling is done normally by conventional cooling where water is circulated around the collector to transfer the heat through its heat transfer capability. The proper electron beam spread is achieved with the optimization of collector and surrounding magnet parameters through an electron beam dynamics tool [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Similarly, the collector thermal behavior is achieved through the optimization of collector thickness and cooling system parameters with the help of a thermal analysis tool. Therefore, the collector system needs two design aspects related to electrical design and thermal design, respectively. The collector will influence the distribution of dissipated power, we proposed a curved profile collector to make the dissipated power more uniformly. This design has increase power capacity and reduced the maximum temperature of collector.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Design of Undepressed Collector","content":"\u003cp\u003eIn this paper design methodology of undepressed collector for a gyro-TWT has been described. The collector is a waveguide to collect spent electron beam and dissipated their energy on the collector as heat and dissipated as heat without any attempt to recover energy from it through voltage depression. EGUN code has been used for the design of the un-depressed collector for Gyro-TWT. The length and radius of the collector for Ka-band Gyro-TWT have been optimized using EGUN simulation and discussed. The analyses consider effective and the uniform electron beam spreading as well as the wall loading within the limits [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. To avoid the melting of the collector surface, it requires thermal and structural analysis of the collector. The overall performance of the device depends upon the power dissipation process of the collector. The electron beam profile is designed to strike on a large extended length or surface around middle portion of a collector so that there is no back reflection towards the interaction structure from the collector as well as there is no bombardment of electron beam on the RF window. Design of electron beam spread is made is in such way that the wall loading for collector surface should not be more 1.0 kW/cm\u003csup\u003e2\u003c/sup\u003e. Electron beam analysis is needed for the electrical design of collector, which helps in getting the maximum electron beam spread. This is carried out with the help of a commercially available and widely used the electron beam analysis code EGUN [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Before the analysis, some design goals have been set up for the optimized collector design. These goals may be defined as collector length should be such that electron beam should not touch the collector end, electron beam spread should be maximum and should be around the center of the collector, magnetic field value around the collector should be as low as possible, coolant temperature should not be more than 50 degree centigrade etc. The analysis of electron beam collector helps to optimize the collector dimensions and to achieve the maximum electron velocity spread on collector surface through the magnetic field optimization. It is found that the magnetic field plays a very important role in the optimization of the length and the radius of the collector. Electron beam analysis is carried out with the help of EGUN code to study the beam spread over the collector surface. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the electron spent beam parameters of collector for Ka-band Gyro-TWT. The electron beam simulation is carried out using 30 beamlets with the real energy distribution of the beam. The beamlets represent the beam power equivalent to the 550 kW. Initially, the electron beam energy is 650 kW generating from electron beam source and after the beam wave interaction 100 kW RF power is taken out of the window. The rest 550 kW power is remained with the electron beam and needs to be dissipated on the inner surface of the collector. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the spent beam profile at collector surface without the use of any additional magnetic coil around the collector. The dimensions of collector has been optimized as length equal to 500 mm and radius equal to 35.0 mm, thickness is 20.0 mm after lot of iterations to get the best possible landing of the spent electron beam. The iterations is carried out to get best, that is, the maximum uniform electron beam spread in the middle part of the collector. It is found that a two layer system of magnet systems yields the optimized result of the electron beam spread of 300 mm.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eDesign parameters of Collector for Ka-band Gyro-TWT\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eS.N\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eParameters\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eValues\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBeam Voltage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e65 kV\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBeam Current\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10 A\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVelocity Ratio\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLarmor Radius\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.4 mm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBeam Radius\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.2 mm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWall loss\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.51 kW/cm\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDissipation Power\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.43 kW/cm\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8.\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCollection Area\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1231 cm\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e"},{"header":"Thermal Design of Collector","content":"\u003cp\u003eA system is heated under the influence of some sort of heat flux. This is also true for the collector. The high energetic spent electron beams are incident on the collector surface and thus the temperature of the collector is increased. It is always preferable to maintain the temperature of the collector within the limit so that there is no thermal stress on the collector body during the operation of the device. The thermal behavior is estimated through thermal analysis. The ANSYS code has been used for the thermal analysis [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Two types of thermal analysis can be performed, such as steady state analysis and transient analysis, respectively. The equilibrium temperature distribution within a structure is estimated through a steady state thermal analysis to determine steady heat flow rates. A transient thermal analysis is used to determine the temperature distribution in a structure. Heat load can be applied on the wall surface in the form of heat flux or heat generation rate or specified temperature in each of the thermal analyses [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The thermal design of collector for Gyro-TWT is carried out to estimate the safe collector temperature. On the basis of the simulation, the thickness of the collector, collector shape and the water flow rate have been finalized. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the 3D view of the collector geometry for Ka-band Gyro-TWT. In the cooling system water is used as coolant for the thermal study. The thermal and mechanical properties of water and OFHC copper are given in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e respectively [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. After meshing in the collector geometry, the material properties are applied. After that, the loads and the boundary conditions are applied. The power density of 300 mm spread is 0.43 kW/cm\u003csup\u003e2\u003c/sup\u003e. However, in the thermal analysis, for the sake of convenience, the average wall loss is applied on the collector surface along the length or surface equivalent to the electron beam spread.\u003c/p\u003e\u003cp\u003eThe basic property of water like density, viscosity, thermal conductivity, etc. change with the rise in temperature and in the thermal analysis, the changed values of these parameters are used. After finding the optimized heat film coefficient, the hydraulic diameter is found for a given coolant flow rate through. In this respect, a typical plot has been created between water flow rate and hydraulic diameter for various values of heat film coefficients [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. It is very clear that the hydraulic diameter increases with increase in the water flow rate at a given value of heat film coefficient whereas hydraulic diameter decreases with increase of heat film coefficient at a given water flow rate. However, the collector surface temperatures decrease with the increase of the heat film-coefficient. Two cases of power dissipations have been studied, such as, 550 kW dissipated spent electron beam power when 100 kW RF power is generated and total 650 kW spent electron beam power when no RF power is generated. The studies have been carried for various inlet water temperatures such as 288K − 293K and hydraulic diameters ranging from 4.5- 5.0 mm diameter. It is always desired to achieve the inner collector surface temperature around or less than 473 K which is easily obtained in the simulations through these simulated results. The maximum temperature on the surface of collector is 220\u003csup\u003eo\u003c/sup\u003eC.The typical thermal analysis results for both situations related to 550 kW and 650 kW power dissipations have been carried out. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e showing the temperatures of inner and outer surfaces of the collector with the 550 kW and 650 kW power dissipations for different water flow rates. From these simulated results, it is very clear that in all the cases the inner and outer temperature rise time becomes constant after 2–3 sec. and decreases with increase in water flow rate. The maximum inner and outer temperature variation of depressed collector with heat film coefficient (h) shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The dissipated power is distributed in the axial range of 300–1000 mm and maximum dissipated power is 0.43 kW/cm\u003csup\u003e2\u003c/sup\u003e. The analytical dissipated power with axial distance of collector shown in the Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. The collecting profile is a rectangular which is uniform. In this paper thermal analysis of the undepressed collector for ka-band gyro-TWT has also been carried out using ANSYS software. The thermal analysis of the collector, during extreme case of operation has been carried out. A transient thermal analysis has been used to determine the temperature distribution as a function of time.\u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eProperties of water as a coolant for the cooling system\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameters\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eUnits\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eValues\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDensity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eKg/m\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e988.21\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eViscosity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNS /m\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.855x10\u003csup\u003e-3\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eConductivity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eW/m K\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.58\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThermal and mechanical properties of OFHC copper\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParameters\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eUnits\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eValues\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDensity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eKg/m\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8960\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThermal Conductivity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eW/m K\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e334\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEmissivity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSpecific Heat\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eJ/(kg.K)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e385\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYoung’s Modulus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGPa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e110\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePoisson’s Ratio\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.33\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThermal expansion Coefficient\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eK\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e17E\u003csup\u003e-6\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn conclusion, it has been established that available collector design is capable of handling the thermal and mechanical loading in a 100 kW power. The design of Un-depressed collector for Ka-band Gyro-TWT is presented in this paper. The initial estimation of collector dimensions length and diameter have been estimated with the help of analytical expressions subjected to the technical limit of wall loss. The trajectory, thermal and structural analysis is carried out for the design of Un-depressed collector. The simulated results have been optimized the collector length 500 mm and collector radius 35 mm with the minimum heat loading of 0.43 kW/cm\u003csup\u003e2\u003c/sup\u003e for uniform electron beam spread. The maximum temperature is 220 \u003csup\u003e0\u003c/sup\u003eC on the inner surface of the collector and 47 \u003csup\u003e0\u003c/sup\u003eC on the edge of the collector outer surface at optimized 3x10\u003csup\u003e5\u003c/sup\u003eW/m\u003csup\u003e2\u003c/sup\u003e.K heat film coefficient (h).\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis work was carried out under a SERB-DST sponsored project.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eNusinovich GS (2004) Introduction to the physics of Gyroton, Maryland, JHU, USA\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChu KR (2002) Overview of research on the Gyrotron traveling wave amplifier. IEEE Trans Plasma Sci 30(3):903\u0026ndash;908\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eEdgecombe CJ (1993) Gyrotron Oscillators: Their principles and practice. London (UK) Taylor \u0026amp; Francis Ltd.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGilmour AS Jr., Klystrons TW, Tubes (2011) Magnetrons, Crossed-Field Amplifiers, and Gyrotrons. Artech House, Boston, MA, USA\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDu CH, Liu PK (Oct 2009) A Lossy Dielectric-Ring Loaded Waveguide with Suppressed Periodicity for Gyro-TWTs Applications. IEEE Trans Electron Devices 56:2335\u0026ndash;2342\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChu KR, Barnett LR, Lau WK, Chang LH, Kou CS (1990) Recent developments in millimeter wave Gyro-TWT research at NTHU. Int Electron Dev Meeting Tech Dig, pp. 699\u0026ndash;702\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRan Y, Di Wang H, Li M, Mu Yuanyuan Lian, and Yong Luo Design of Collectors for High Average/Continuous-Wave Power Gyro-Devices. IEEE Trans Electron Devices, 66, 6, pp.1512\u0026ndash;1518, March 2019.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDu CH, Liu PK (2009) Stability study of a gyrotron-traveling-wave amplifier based on a lossy dielectric-loaded mode-selective circuit. Phys Plasmas, 16\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTang Y, Luo Y, Xu Y (November 2014) Design of a Novel Dual-Band Gyro-TWT. IEEE Trans Electron Devices 61:3858\u0026ndash;3863\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiu B et al (2013) Experimental study of a Q-band gyro-TWT, in Proc. IEEE 14th Int. Vac. Electron. Conf. (IVEC) May\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBarnett LR, Lau YY, Chu KR et al (1981) An Experimental Wideband Gyrotron Traveling-Wave Amplifier. IEEE Trans Electron Devices 28:872\u0026ndash;875\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHermannsfeldt EGUN (1979) W.B., Stanford Linear Accelerator Center, Stanford University Report SLAC-226\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eUser Manual Ansys- (2019) Ansys Mechanical Finite Element Analysis Software, Canonsburg, PA, USA, 2019\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eIncropera FP, DeWitt DP, Bergman TL, Lavine AS (2007) Introduction to heat transfer, (5th Ed), John Wiley \u0026amp; Sons, ISBN: 978-0-471-45727-5\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKumar A, Goswami UK, Poonia S, Singh U, Kumar N, Alaria MK, A.Bera and, Sinha AK (2011) Integrated design of undepressed collector for low power gyrotron. J Infrared Millim Terahertz Waves 32(6):733\u0026ndash;741\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGoswami UK, Singh U, Kumar N, Sahu NK, Kumar A (2013) .Yadav,R.L dua and A.K.Sinha Development of cooling system for gyrotron collector. J Fusion Energy 32(4):518\u0026ndash;522\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Gyro traveling wave tube (Gyro-TWT), Thermal analysis, Undepressed, Dissipation","lastPublishedDoi":"10.21203/rs.3.rs-8072976/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8072976/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe design and analysis of an undepressed collector for Ka-band Gyro-TWT have been described in this paper. Initially, trajectory analysis has been carried out after preliminary design of the un-depressed collector. EGUN code and ANSYS software are used for trajectory and mechanical analysis respectively. Thermal design has also been carried out for finalization of collector geometry such as collector thickness, collector length and the estimations and optimizations of temperatures on the both inner and outer collector surfaces with the reasonable flow of coolant around the collector. The uniform electron beam spread of 300 mm has been achieved for wall loss of 0.43 kW/ cm\u003csup\u003e2\u003c/sup\u003e for the collector diameter and length equal to 70 mm and 500 mm respectively. The maximum temperature has been obtained on the collector is 220\u003csup\u003eo\u003c/sup\u003eC.\u003c/p\u003e","manuscriptTitle":"Design of Undepressed Collector for Ka-band Gyro-TWT Amplifier","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-12 19:35:17","doi":"10.21203/rs.3.rs-8072976/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ddce5a73-0302-48ed-a817-f7c50aba78cd","owner":[],"postedDate":"November 12th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-12T19:35:17+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-12 19:35:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8072976","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8072976","identity":"rs-8072976","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}