A5007013648- Gyrotron and Vacuum Electronics Research
- Microwave Engineering and Waveguides
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Advanced Antenna and Metasurface Technologies
- Field-Flow Fractionation Techniques
- Fluid Dynamics and Turbulent Flows
- Laser-Plasma Interactions and Diagnostics
- Magnetic confinement fusion research
- Pulsed Power Technology Applications
- Laser-induced spectroscopy and plasma
- Photonic and Optical Devices
- Fusion materials and technologies
- Nanofluid Flow and Heat Transfer
- Laser-Matter Interactions and Applications
- Phase Equilibria and Thermodynamics
- Radioactive element chemistry and processing
- nanoparticles nucleation surface interactions
- Ion-surface interactions and analysis
- Material Properties and Failure Mechanisms
- Microwave and Dielectric Measurement Techniques
- Fluid dynamics and aerodynamics studies
- Advanced X-ray Imaging Techniques
- Electromagnetic Simulation and Numerical Methods
- X-ray Spectroscopy and Fluorescence Analysis
Vinnytsia Mykhailo Kotsiubynskyi State Pedagogical University
2023-2024
SCIVP of Veterinary Medicinal Products and Feed Additives
2003-2024
V. N. Karazin Kharkiv National University
2014-2023
Institute of Mathematics
2023
Kharkiv Institute of Physics and Technology
2014-2023
National Academy of Sciences of Ukraine
1998-2023
Universität Hamburg
2018-2023
National Technical University "Kharkiv Polytechnic Institute"
2023
Deutsches Elektronen-Synchrotron DESY
2018-2023
Center for Free-Electron Laser Science
2018-2023
We review the results of our research on damage mechanisms in materials irradiated with femtosecond free-electron-laser (FEL) pulses. They were obtained using hybrid approach, X-ray-induced thermal and non-thermal transitions (XTANT). Various are discussed respect to pulse fluence material properties examples diamond, amorphous carbon, C 60 crystal, silicon. indicate following conditions: those producing melting targets as a result electron-ion energy exchange; phase due modification...
X-ray diffraction of silicon irradiated with tightly focused femtosecond x-ray pulses (photon energy, 11.5 keV; pulse duration, 6 fs) was measured at various intensities up to 4.6×10^{19} W/cm^{2}. The measurement reveals that the intensity is highly suppressed when reaches order 10^{19} With a dedicated simulation, we confirm observed reduction can be attributed change in individual atomic scattering factors due ultrafast creation ionized atoms through photoionization, Auger decay, and...
The problem of power degradation due to the dominant ohmic losses in gyrotron cavity is considered. As an example, operating performances FU CW III Fukui University are investigated numerically. It found that, for this gyrotron, there a significant divergence between classical and self-consistent computations loss-induced degradation. reason that former ignore effect on beam-wave interaction efficiency.
The coupled transcendental equations describing cutoff frequencies of TE and TM modes are deduced for a rectangular waveguide with arbitrary wall impedance. In the case modes, their generalization is made to guiding structure, which possesses both distributed impedance inhomogeneous dielectric loading. Effective obtained imperfectly conducting surface incorporating periodic corrugations along direction mode propagation. Circular bounded by such corrugated considered as numerical examples....
Cavity modification is proposed with the aim of enhancing continuous frequency tunability a gyrotron. The can be applied to both uniform and tapered gyrotron cavities involves just using an additional cavity section. It ensures larger effective length thus lower starting current for higher order axial modes. As consequence, tuning band increased significantly. Moreover, beneficial smoothing variations output power within band.
A new computer-aided procedure of designing waveguide manifold multiplexers, which combines a rigorous numerical analysis electromagnetic characteristics the key elements structure and simple circuit engineering design technique, is proposed. This enables one to obtain required multiplexer without any experimental corrections at minimum computer time expense. Typical results are given demonstrate efficiency method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML"...
The main goal of the paper is to present a new generalized mode-matching (GMM) approach both mode bases and S-matrices calculation complicated waveguide circuits. Development GMM procedures makes it possible realize totally automatic algorithms for wide set configurations avoiding specialized analytical treatment each boundary-value problem. Moreover, background linking up interface tools circuit geometry specification editing provided by together with special recognizing object data...
It is found that a cavity design strategy proposed recently to enhance the continuous frequency tuning band of sub-terahertz second-harmonic gyrotron aggravates problem competition between operating mode and first-cyclotron-harmonic (fundamental) modes. A stepped coaxial inner conductor in this article as means for selective suppression most dangerous fundamental competitors. shown that, with proper choice mode, effect only distinct unwanted competing In case, performance slightly sensitive...
We revisit the problem of diffusion in a driven system consisting an inertial Brownian particle moving symmetric periodic potential and subjected to time-periodic force. reveal parameter domains which is normal long time limit exhibits intriguing giant damped quasiperiodic oscillations as function external driving amplitude. As mechanism behind this effect, we identify corresponding difference number locked running trajectories that carry leading contribution coefficient. Our findings can be...
In the fixed-field (cold) approximation, a generalized formula is derived for starting currents of eigenmodes excited by an electron beam in gyrotron cavity with mode conversion. Tapered cavities gradual and abrupt transitions are considered as examples. It shown that effect conversion on current consists mainly change diffractive quality factor and, therefore, small low losses. For such cavities, our good agreement single-mode, self-consistent (hot) calculations beam-wave interaction. The...
Nano-mechanisms of solid-phase bonding tungsten and tantalum, which are implemented in the manufacture a neutron source target for research nuclear facility (RNF) NSC KIPT, considered. This is new type reactor, core intensity fission reaction uranium isotope 235U controlled by an electron accelerator. An installation joining metals solid phase described, its parameters given, as well joined metals. electron-probe X-ray spectral analysis interface between samples was carried out. The physical...
The opportunity of an effective usage a stepped approximation for the calculation cutoff frequencies and eigenfunctions waveguides with complex cross-sections is shown. It recognized that such approach productive analysis optimization polarizers based on sections circular rectangular ridges. results comparison experimental data are represented.
Elementary convection cells (ECC) are formed in horizontal layers of liquid heated from below, and they experimentally investigated this work. Results experimental studies were adequately described by the theoretical model ECC. It is shown that addition aluminum powder to oil transforms a suspension, such boundary conditions on solid wall can be regarded as free because there slip through tape pure oil. Change character confirmed results numerical processing formation convective rings layer...