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An advanced three-dimensional finite-element S-parameter-simulation tool for microwave tubes is designed. This simulator is based on the second order hierarchical vector finite element method and the proposed combining p-type multigrid and multifrontal block incomplete Cholesky preconditioner. This simulator has shown the high available accuracy and the high-efficiency computational performance for...
In 1919 the Department of Electrical Engineering (EE) was established in Tohoku University (at that time, Tohoku Imperial University). In this Department a growing tendency towards research featured in science and technology for electrical communication. Great efforts made in these fields produced pioneering studies such as those of the Yagi-Uda antenna and slotted-anode type magnetrons in the late...
An approach is presented for controlling the profile of heat dissipation density on the surface of collectors of a high power gyrotron. A 1 MW, 110 GHz gyrotron which has two depressed collectors, is used as a vehicle of study. A subsidiary coil has been added to the design configuration. It was found that for a particular number of ampere turns carried by it, all peaks of heat dissipation density...
Recent developments to microwave tube simulator suite (MTSS) are reported in this paper. The MTSS is a full-featured tightly integrated software package for microwave tube analysis and design. It includes a commercial grade user interface and three physics simulators. The electron optics simulator is a finite-element (FE) 2-D and 3-D electrostatic steady-state beam trajectory code that has been used...
The Magnetic Focus Simulator (MFS) is a three-dimensional finite-element method code. It is used to model the magnetic field in the microwave tube and supplies the external magnetic field for the Electron Optics Simulator (EOS) and the Beam Wave Interaction Simulator (BWIS).
High power microwave tubes are devices which generate or amplify electromagnetic radiation in the frequency range of 0.3GHz to 300GHz (microwave and millimeter wave frequencies) at high peak and high average power level. Among the various kinds of microwave tubes, gyrotrons are the most well known devices which used for amplification and generation of energy at high power levels especially for ECRH...
Over the last five decades, R&D, industry and academia in India have contributed significantly to electromagnetic analysis, numerical modelling and simulations and technologies in the area of microwave vacuum electronic sources, that culminated in the development and productionisation of a number of microwave tubes in India and enabled the concerned community to venture towards a number of new...
We demonstrate that on considering an electric-field longitudinal profile in the shape of a two-level transition curve the monotron conversion efficiency can attain values in excess of 30%, 1.5 times as high as that obtained from the conventional uniform field distribution. This is accomplished by using two cavities electromagnetically coupled by an annular slit crossed by an electron stream. A two-cavity...
This paper describes the simulation of a single stage depressed collector using PIERCE and CST Studio including secondary electron emission effects. This collector was developed and integrated with a linear beam tube. The experimental efficiency of the collector agrees well with the simulated efficiency of the collector. The thermal analysis of the collector also has been carried out using ANSYS and...
Backward wave oscillation (BWO) and other parasitic oscillation are encountered in the process of manufacturing W-band TWT. In order to eliminate the oscillation, a kind of attenuation material is coated to the folded waveguide wall. This method presents a good performance to enable stable working of the TWT and increase the output power to 15W at the same drive level.
The majority of medical and industrial linear accelerators (LINACs) in use today operate at S-band. To reduce size and weight, these systems are gradually migrating toward X-band. The new LINACs will require suitable RF components to power them. In anticipation of this market, L-3 Communications Electron Devices Division (EDD) has recently developed a suite of RF sources operating at 9.3 GHz to complement...
Emission properties of nanosized scandia doped dispenser (SDD) cathodes tested at pulse mode with different pulse widths and duty cycles as well as at DC mode are reported and discussed in this paper.
In this paper, a scheme of obtaining the maximum theoretical overall efficiency is explored by optimizing the helix pitch profile of a TWT based on the collectability of spent beam. The detailed design of a Ku-band helix TWT is described according to three optimization goals (theoretical overall efficiency, theoretical collector efficiency and electronic efficiency). The simulation results indicate...
For reliable operation of high power microwave sources such as high power gyrotron demands stringent vacuum conditions to be fulfilled. In this paper, the vacuum requirements of a 42 GHz, 200 kW CW/ long-pulse gyrotron has been presented and also includes requirement for its heat treatment and vacuum processing.
The Orotron is a device which is capable of producing moderate (few watts) to high power levels (few kilowatts) of millimeter and sub-millimeter wavelength radiation in the frequency range from GHz to Terahertz. It consists of an open resonator containing rectangular metal grating periodic RF structure and a sheet electron beam. In this paper, 100 GHz RF interaction structure for Orotron has been...
A one dimensional nonlinear time-dependent theory for helix traveling wave tubes in beam-wave interaction is studied. A generalized electromagnetic field is applied to the expression of radio frequency field. The substitution of a spatial average over a wavelength for a time average over a wave period is used in the equation of radio frequency field. The space charge field of electron beam is treated...
Optimum regimes are found and the limiting parameters doing twice-quadruple multiplication of frequency in a gyrocon with electronic efficiency more than 90 % are adjusted.
In satellite systems, on-board repeaters are required to provide higher and higher levels of RF power. Specifically in Ka band, a substantial increase of RF power is requested in some applications like HDTV and internet to improve the available data rate. In order to respond to this demand, Thales Electron Devices (TED), with the support of CNES (French Space Agency), is developing a TWT (TH4816)...
Alignments of different constituent components of an electron gun plays a crucial role in the final performance of the device. This paper presents a 3-D study of the tolerable limits of alignments of a Pierce type convergent electron gun assembly, namely, concentricity of the integration of the gun with the anode, an angular tilt in the placement of anode and an angular tilt in the placement of the...
In this paper, the design of the conventional electron beam spreading system of the gyrotron collector consisted of the magnetic shade and two pairs of coils is presented. The simulation and experiment of the electron beam distribution on the collector wall of the gyrotron applied to the electron spreading system is completed.
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