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The results of the calculation of the distribution of the magnetic field in the magnetic periodic focusing system with different screen configurations are presented. The calculations of the electron beam trajectories in the gun for different values of the field at the cathode are showed. The values of the magnetic field at the cathode depending on the ratio of the diameter of the screen to the outer...
The propagation of current and velocity sinusoidal modulation in plane diode using 2D numerical model is studied. The linear regions are obtained when the first harmonics of current and velocity between cathode and anode are increasing proportionally with increasing of harmonic in start points. For two cases of modulation in start points — modulation of current and modulation of velocity — numerical...
This report presents the results of calculation of electron-optical system consisting of a sheet CNT field emission cathode with a microgrid spaced from the surface of the emitter at 100 microns. On the basis of experimental data, it has been designed electron-optical system with a sheet CNT cathode with linear convergence of 6,25, and with the beam current density of 4,46 A/cm2. The thickness of...
The method and code of electron gun calculation in time domain are presented. The Poisson equation in 2D axial region is solved by integral equation method. For modeling in time domain algorithm «step by step» is used. Three meshes — one spherical and two rectangular — are used for potential calculation and equation of motion solving. The consistent scheme of distribution between mesh points of particle...
The method of digital calculation of noise figure for helix TWT using 2d code are presented. The electron beam in helix structure enter was obtained after electron gun calculation with current and velocity modulations on cathode. The zero initial conditions for electron beam in helix enter for interaction calculation was changed by conditions which taken into account current and velocity modulations...
This paper presents the results of numerical simulation and experimental researches of high power broadband TWT in X/Ku frequency range. Described TWT provides the output power more than 500 W with the operating frequency greater than 1 octave and gain coefficient more than 30 dB. In this TWT is used periodic magnetic focusing system for maintaining the electron beam. TWT has a waveguide output and...
The method of digital calculation of current and velocity disturbances propagation in converging electron streams are presented. The Poisson equation in 2D axial region is solved by integral equation method. For modeling in time domain algorithm «step by step» is used. Three meshes — one spherical and two rectangular — are used for potential calculation and equation of motion solving. The cathode...
Single-sheet and multiple beam electron emitters based on thermionic minicathodes for terahertz traveling-wave tubes have been studied. Data are presented for impregnated blade thermionic cathode with dimensions 0.1 × 0.7 mm and a maximum current density of 114 A/cm2 in a pulsed mode. A variant of the five-beam electron gun with 0.25-mm-diameter cylindrical minicathodes in cells of a control grid...
The results of calculation of five stage depressed collector of helix C-band TWT for space communications are described. Also was made the optimization of construction reflector with zero potential for raising of saturated efficiency.
The characteristics of electron-optic systems with plane and cylindrical cathodes and EOS with full accompaniment by magnetic field for thin sheet beam forming are discussed.
The numerical and experimental study of electron beam in TWT with higt microperveance and quasi-hollow forms is fulfilled. The results of the numerical study of electron beam structure correspond to the experimental results.
The results of modeling the sub-millimeter TWT electron optical system with a low-voltage control based on the experimental data of the planar array cathode-gate structure with carbon nanostructures are performed in this work. It is shown that the cathode-gate structure including in the analyzed field emission electron gun manufacturing by lithographic processes and CVD technologies may provide the...
The results of using three-dimensional codes for investigation of magnetic field transverse component influence on beam transmission in TWT EOS with next parameters: SWS voltage - 4 kV, beam current - 130 mA, beam focusing - PPM with amplitude value 2700 Gs, tunnel diameter - 1,1 mm are presented.
The results of calculation and experimental measures of helix C-band Traveling Wave Tube for space communications are described. Optimization of helix pitch and five stage depressed collector have allowed us to receive 63% of saturated efficiency and 41.5% of electron efficiency.
The influence of neighboring tips upon each other in matrix carbon field emission cathodes is studied. The constructions of matrix cathodes, containing tip or wedge mini cathodes, and forming beams with currents up to several tens of mill amperes and diminished transversal velocities are suggested.
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