Microfabricated vacuum-tube millimeter- and THz-band sources are of great interest for numerous applications such as communications, radar, sensors, imaging, etc. Recently, miniaturized sheet-beam traveling-wave tubes for operation at sub-THz and THz bands have attracted a considerable interest. In this paper, we present the results of modeling and development of slow-wave structures (SWS) for medium power (10-100 W) traveling-wave tubes (TWT) amplifiers in near-THz frequency band. Different types of SWSs are considered, such as double-vane SWS for TWT with a sheet electron beam, folded-waveguide SWS, and novel planar SWSs on dielectric substrates.

Electron-optical systems are synthesized to form a converging sheet electron beam with a compression of 15 and 20, a cross section of 0.05 × 2 mm, and a current density of 100 A/cm 2 in the presence of complete magnetic shielding of field-emission cathode. Deformation of low-perveance flux in the presence of magnetic field in the drift tunnel of slow-wave structure is analyzed with the aid of 3D computer simulation of the electron-optical system with the sheet electron beam.

Синтез электронно-оптических систем с компрессией ленточного пучка для ламп бегущей волны терагерцевого диапазона© А

Microfabricated vacuum power amplifiers and oscillators operating at THz frequencies have attracted a great interest. Among them, linear-beam Cherenkov devices such as travelling-wave tubes (TWT) and backward-wave oscillators (BWO) have been actively studied. For miniaturized devices, a possibility of low-voltage operation is of primary importance, since decrease of voltage allows reduce of size and weight of the device. In particular, promising planar slow-wave structures (SWSs) utilizing a metallized meander mi-crostrip line on a dielectric substrate has been proposed [1]. Later, similar SWSs have been considered in [2–4]. In this paper, we present the results of numerical simulation, fabrication, and cold measurement of the microstrip meander-line and interdigital SWSs. Schematics of the SWSs are shown in Fig. 1(a) and Fig. 1(b), respectively. Fig. 1(c) shows qualitative drawing of their dispersion diagrams. One can see that the meander and interdigital SWS are suitable for TWT and BWO operation, respectively. The proposed structures exhibit high slowdown factor that is profitable for low-voltage operation.

For miniaturized vacuum-tube electron devices at millimeter and submillimeter (THz) bands, a possibility of low-voltage operation is of primary importance. Planar slow-wave structures (SWS) on dielectric substrates are favorable for the low-voltage operation. In this paper, we discuss design, fabrication and cold test of millimeter-wave planar SWSs. We consider the meander and interdigital SWSs, which are designed for operation in O-type traveling-wave tube amplifier and backward-wave oscillator, respectively.

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 beam in the interaction space is 0,16 mm. In this case, the simulation of the sheet electron beam, generated by electron gun has shown feasibility of obtaining of low-perveance flow with a small deformation in beam tunnel 0,3×0,8 at 25 mm slow-wave system length.

A traveling-wave tube of the millimeter range belonging to the short-wavelength region with a sheet electron beam and a slow-wave structure of the double grating type is studied. Its dispersion characteristics and coupling impedances for various spatial harmonics are calculated. The issues of design of the electron-optical system are discussed. The focusing of a sheet electron beam with a high current density by a uniform magnetic field is modeled.

Sheet-beam traveling-wave tubes (TWTs) and backward-wave oscillators (BWOs) with grating slow-wave structures (SWS) have attracted a considerable interest as THz and sub-THz power amplifiers [1]. Such devices can find wide application as compact sources with relatively high power for communications, radar, sensors, imaging, etc. In this paper, we present the results of research aimed at development of the G-band (0.22 THz) TWT amplifier with double- and singlegrating SWS and a sheet electron beam. For 3D numerical modeling we developed a fast and accurate approach based on the integral equation method (IEM). Detailed description of the method is presented in [2]. Using the code, we optimized the dimensions of the SWS to achieve rather wide passband about 70 GHz and interaction impedance about 1 Ohm, which is sufficient to achieve 20 dB gain.

A fast and accurate code for calculation of eigenwaves in single-and double-vane slow-wave structures (SWS) is developed. Such SWS are used in sheet-beam traveling wave tubes (TWTs) and backward-wave oscillators (BWOs) at sub-THz and THz frequencies. Results of numerical modeling of SWS for a G-band sheet-beam TWT are presented.

Algorithm allowing to study the atomic structure and electronic structure of nanoemitters based on carbon nan-otubes (CNT) was developed by quantum approach for the first time. This algorithm takes into account the heterogeneity of the electric field. It was established that the distribution of the electrostatic field intensity varies greatly with the advent of the atoms of the plasma in the area of CNT framework.

We propose a method for calculation of a periodic slow-wave system designed as a double comb immersed into a rectangular waveguide. The approach is based on solving a system of integral equations obtained by the method of field matching in different regions. The system of integral equations is reduced to an algebraic system of linear homogeneous equations using Galerkin’s method with allowance for the singular behavior of the field on the edges of the comb pins. The results of calculating characteristics of the slow-wave system of the millimeter-wave traveling-wave tube with a sheet electron beam are presented.

New approaches to the problems of criticality of field emission with respect to the construction and technological factors are analyzed, and examples of their practical application are considered. These approaches provide practical applications of carbon nanotubes and carbonaceous planar-edge field-emission structures in extreme electronics areas.

The synthesis of carbon nanotubes (CNTs) in the holes was carried out by TCVD-method with using metal Fe-catalyst. The holes of depth of ~ 7 μm were obtained in the tripartite structure Si/SiO2/Cr by means of conventional photolithography. The matrix period is 25 μm, the area of each square "window" in the layer of Cr is 100 μm2. The field-emission current density of 26 μA/cm2 was registered at applied electric field of 4 - 5 V/μm. Such structures will be used to create matrix cathodes for field-emission displays.

Modifying the polycrystalline phosphors Y2O3:Eu and Y2O2S:Eu in order to allow their application as submicron composite materials for electrovacuum luminescent video-imaging devices and light sources is considered. The effect of synthesizing such materials through the use of H3BO3 on their crystal structure, spectral characteristics, and photo- and cathodoluminescence intensities is investigated.

The problems connected with creation of a new class of low-voltage multibeam electrovacuum devices of a millimetric range of low power are discussed. In the amplifier the matrix field emission cathode and input and output planar multiline waveguide with tape-like conductors in which transverse-extended interaction is realized. With reference to the given waveguide with the help of the strict electrodynamic theory the geometrical and constructive conditions providing the maximal coupling resistance, reaching 150-200 Ohm are investigated

The crystalline phosphors Y 2 O 3 :Eu and Y 2 O 2 S:Eu are widely used as the red component of color cathodoluminescent displays of different purpose. Nevertheless, their chromaticity coordinates does not completely meet the requirements which are set for color displays. Along with pigmentation, the method of enhancing of Y 2 O 3 :Eu radiation band intensity in deep red range is known (Morozova, 2002). It lies in borate acid adding to the flux composition during synthesis and enhances the red band intensity in the light emission spectrum. However, the nature of the influence of that modification on the photo- and cathodoluminescence of crystals is not still studied well. The study of influence of treatment by H 3 BO 3 under different conditions during Y 2 O 3 :Eu crystals synthesis on their crystalline structure, spectral characteristics and their photo- and cathodoluminescence intensity is carried out. Changes in luminescent properties of Y 2 O 2 S:Eu polycrystals in case of their synthesis from initial oxides which were obtained using borate flux is examined as well

This paper reports the synthesis of carbon nanotube films on a flat substrate. The Fe catalyst is previously deposited on the substrate as a solid film with thickness reaching 10 nm. At the first stage of growth nanotubes pushed up the whole iron film but then due to the difference in the speed of growth, the catalyst film is broken to large patches.

We review the state-of-the-art in the carbon nanotube (CNT) electronics. The emphasis is made on actually created devices. The history of discovery of fullerenes is outlined and their properties are considered. Experimental discovery of nanotubes and nanotube synthesis technologies are reviewed. The CNT conductivity dependence on the geometrical structure of nanotubes is discussed. Various nanoelectronic CNT devices, such as nanowires, heterojunctions, diodes, and field-effect transistors are presented. Quantum properties of CNTs at low temperatures are discussed. CNT-based mechanical devices, memory elements, and switches are considered. Field emission properties of CNTs are analyzed. The data on the developed CNT-based light-emitting elements and the manufactured pre-production models of CNT flat-panel displays are given.