Simulation of the Helical Slow-Wave Structure of a High-Power Traveling-Wave Tube
The electrodynamic characteristics of the helical slow-wave structure of a high-power pulse traveling-wave tube operating in the centimeter wavelength range are calculated by means of the solution of the dispersion equation and simulation. Special attention is focused on the effect of a helix wire profile on the electrodynamic characteristics of the system. The results of the theoretical study are compared with the experimental data.
This paper considers the model of amplification of electromagnetic millimeter waves by non-relativistic electron beams in one-dimensional periodic electrodynamic systems. As slow-wave structures are investigated systems such as “winding waveguide” and “counter-pins”-type suitable for use in the millimeter range. The main directions of research are: - development of a traveling-wave tube model on the basis of the differential theory of excitation of electrodynamic systems by currents; - modeling and calculation for simplified waveguide-resonator model of electrodynamic properties of slow-wave structures such as "winding waveguide" in the millimeter range; - representation of a waveguide-resonator model of "winding waveguide"-type slow-wave structure, composed of segments of rectangular and U-shaped waveguide; - obtaining by a waveguide-resonator model coefficients of the transmission matrix, which allows to analyze the dispersion and coupling impedance in the band of amplified frequencies; - investigation of “winding waveguide"-type slow-wave structure taking into account the geometric phase rotation field in neighboring gaps by linear waveguide-resonator model represented by a chain of quadripoles by means of opposite switching of the induced current in the neighboring interaction gaps and also the first spatial harmonic used in traveling-wave tubes for the calculation of the dispersion; - calculation of a number of options that characterize the basic laws of changes in the properties of “winding waveguide"-type slow-wave structure; - modeling the properties of slow-wave structures such as "winding waveguide" using 3D-codes; - application of the results obtained using the 3D-codes as the numerical experiment to adjust waveguide-resonator model; - model building pin-type slow-wave structures using waveguide-resonator model, customized by experimental reference points. The paper shows that for modeling slow-wave structures such as “winding waveguide” and “counter-pins” waveguide-resonator model customized to the experimentally obtained reference points can be used. As the reference points can also be used the values of deceleration and the coupling impedance obtained by numerical experiment using HFSS. Waveguide resonator models constructed in such way are sufficiently accurate and simple. This paper shows that these models can be successfully used for the calculation of traveling-wave tubes operating in the millimeter range.
In this paper software package for numerical modeling of transformation and propagation of internal gravity waves (IGW) in the World Ocean is presented. Short overview of implemented numerical models is given. They are: extended nonlinear evolutionary equation of Korteveg-de-Vries type with combined nonlinearity with variable coefficients (Gardner equation) and ray model reproducing the effect of refraction in an IGW package. The developed software package is unique and topical for this class of geophysical applications. Description of user interface and main working modes of the software are presented.
The physical-mathematical model of the sensors block of space radiation fluxes parameters monitoring module has been developed. The simulation of the sensors block output has been carried out using the series of the spectra representing space radiation spectra at different spaceship orbits in different phases of the solar activity cycle. The optimisation of the sensors block of space radiation fluxes parameters monitoring module has been carried out based on the simulation results.
A linear theory of the discrete interaction of electron beams and electromagnetic waves in slow-wave structures (SWS) is developed. The theory is based on the finite_difference equations of SWS excitation.The local coupling impedance entering these equations characterizes the field intensity excited by the electron beam in interaction gaps and has a finite value at SWS cutoff frequencies. The theory uniformly describes the electron–wave interaction in SWS passbands and stopbands without using equivalent circuits, a circumstance that allows considering the processes in the vicinity of cutoff frequencies and switching from the Cerenkov mechanism of interaction in a traveling wave tube to the klystron mechanism when passing to SWS stopbands. The features of the equations of the discrete electron–wave interaction in pseudoperiodic SWSs are analyzed.
We consider the possibility to replace an electron beam (EB) by a "hot" equivalent capacitance that will make it possible to use "hot" equivalent circuits and long lines for analysis the EB interaction in TWTs. A sheet EB in the field of the in-phase mode of the slow wave excited by coupled impedance electrodes is considered in this paper.
Generalized error-locating codes are discussed. An algorithm for calculation of the upper bound of the probability of erroneous decoding for known code parameters and the input error probability is given. Based on this algorithm, an algorithm for selection of the code parameters for a specified design and input and output error probabilities is constructed. The lower bound of the probability of erroneous decoding is given. Examples of the dependence of the probability of erroneous decoding on the input error probability are given and the behavior of the obtained curves is explained.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.