A. S. Kozachok
A5057616774- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Fusion materials and technologies
- Superconducting Materials and Applications
- Material Science and Thermodynamics
- Plasma Diagnostics and Applications
- Laser-Plasma Interactions and Diagnostics
- Differential Equations and Numerical Methods
- Geophysics and Gravity Measurements
- Particle accelerators and beam dynamics
- Fluid dynamics and aerodynamics studies
- Astro and Planetary Science
- Scientific Research and Discoveries
- X-ray Spectroscopy and Fluorescence Analysis
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Electron and X-Ray Spectroscopy Techniques
- Differential Equations and Boundary Problems
Kharkiv Institute of Physics and Technology
2002-2015
Kurchatov Institute
2008
This paper presents the latest results on confinement studies in TJ-II stellarator. The inherently strong plasma–wall interaction of has been successfully reduced after lithium coating by vacuum evaporation. Besides H retention and low Z , Li was chosen because there exists a reactor-oriented interest this element, thus giving special relevance to investigation its properties. Li-coating led important changes plasma performance. Particularly, effective density limit NBI plasmas extended...
This paper describes a series of experiments performed in TJ-II stellarator with the aim studying influence magnetic configuration on stability and transport properties plasmas. Plasma potential profiles have been measured several configurations up to plasma core heavy ion beam probe diagnostic. Low-order rational surfaces positioned at different radii observing effect features. edge turbulent has studied that are marginally stable due decreased well. Results show dynamical coupling between...
Energetic ion driven Alfvén eigenmodes (AEs) are believed to be an important element disturbing the transport in a future fusion reactor. The studies of AE properties modern toroidal devices have made crucial contributions reactor relevant physics. AEs conventionally studied by magnetic probes (MPs), which provide poloidal m and n mode numbers their spectral characteristics. Heavy beam probing (HIBP) has become new tool study with high spatial frequency resolution. HIBP TJ-II heliac observes...
This paper presents an overview of experimental results and progress made in investigating density control using Li-coating, transport L–H transitions TJ-II. The Li-coating changes drastically the plasma–wall interaction, decreasing recycling, enlarges substantially operational range device delaying appearance radiative collapse that happens for higher densities, which permits confinement properties much denser plasmas to be studied. Moreover, mode transition has only been achieved after...
The influence of magnetic topology on the formation electron internal transport barriers (e-ITBs) has been studied experimentally in cyclotron heated plasmas stellarator TJ-II. e-ITB is characterized by an increase core temperature and plasma potential. positive radial electric field increases a factor 3 central region when forms. experiments reported demonstrate that depends configuration. Calculations modification rotational transform due to current lead interpretation can be triggered...
The influence of limiter biasing on plasma confinement, turbulence and flows is investigated in the TJ-II stellarator. Experimental results show that it possible to modify global confinement edge parameters with both positive negative biasing. Significant minor modifications structure fluctuations have been observed during transition improved regimes induced by These evidence electric field via multiple mechanisms. investigation relaxation potential fields shows two different characteristic...
This paper presents an overview of experimental results and progress made in investigating the role magnetic configuration on stability transport TJ-II stellarator. Global confinement studies have revealed a positive dependence energy rotational transform plasma density, together with different parametric dependences for metallic boronized wall conditions. Spontaneous biasing-induced improved transitions, some characteristics that resemble those previously reported H-mode regimes other...
The effect of edge biasing on plasma potential was investigated in the TJ-II stellarator and T-10 tokamak. Heavy Ion Beam Probe (HIBP) diagnostic, a unique tool for studying core directly, used both machines. Experiments show that it is possible to modify global confinement parameters with limiter biasing, illustrating direct impact radial electric fields properties. For first time shown column can be charged as whole hot, near-reactor-relevant plasma. evolve two different characteristic...
An advanced 200 keV heavy ion beam diagnostic has been developed for the TJ-II stellarator based on simultaneous utilization of a 30° Proca–Green electrostatic energy analyzer and multiple cell array detector. This innovative design allows instantaneous measurements plasma potential electron density profiles together with their respective fluctuations. In this article we present description main parts (injection system, detectors, control data acquisition system) results obtained during...
The evolution of core quasi-coherent modes has been investigated during the formation electron internal transport barriers (e-ITB) in TJ-II stellarator. These have characterized using heavy ion beam probe and cyclotron emission diagnostics. mode evolves formation/annihilation e-ITB vanishes as barrier is fully developed. observations can be interpreted terms influence sheared flows stability modes.
AbstractIn most helical systems, electron–internal transport barriers (e-ITBs) are observed in electron cyclotron heated (ECH) plasmas with high heating power density. In the stellarator TJ-II, e-ITBs easily achievable by positioning a low-order rational surface close to plasma core because this increases density range which e-ITB can form. Experiments different rationals show dependence of threshold and barrier quality on order (3/2, 4/2, 5/3 …). addition, quasi-coherent modes frequently...
The main TJ-II results since 2012 are presented in this overview. Impurity confinement is studied showing an isotopic dependence of impurity time, asymmetries parallel flows ion-root plasmas and density within a flux surface. In addition, first observations electrostatic potential variations the same magnetic surface presented. Evidence impact three-dimensional structures on plasma L–H transitions also leading role turbulence emphasized by observed temporal ordering limit cycle oscillations...
In this article the Navier -Stokes (NSE) exact transformations to simpler equations is covered.This transformation executed by classical methods of Mathematical Analysis.The solution such than well known NSE.These new essentially facilitate solutions Millennium Problem and different problems numerous applications Applied Mathematics in engineering.
This paper presents an overview of experimental results and progress made in investigating the link between magnetic topology, electric fields transport TJ-II stellarator. The smooth change from positive to negative field observed core region as density is raised correlated with global local data. A statistical description emerging a new way describe coupling profiles, plasma flows turbulence. experiments show that location rational surfaces inside can, some circumstances, provide trigger...
This work deals with the results on flow dynamics in TJ-II plasmas under Li-coated wall conditions, which produces low recycling and facilitates density control access to improved confinement transitions. The low-density transition, characterized by emergence of shear layer, is described from first principles within framework neoclassical theory. vanishing viscosity when approaching transition below explains observation a number turbulent phenomena reported recent years; unifying picture...
Quasi‐coherent oscillations have been observed in TJ‐II plasma with different diagnostics: Heavy Ion Beam Probe (HIBP), ECE, Langmuir probes and Mirnov coils. A recent improvement the signal to noise ratio of HIBP allowed us observe radial structure these from edge core. The quasi‐coherent fluctuations some configurational windows, when density heating power is above a threshold.
In electrostatic energy analyzers of heavy ion beam probes the required accuracy plasma potential measurements is provided by differential detection on split detector. Secondary electrons created detector surface analyzed ions and ultraviolet radiation can strongly disturb measurements. this article we consider influence analyzer operation secondary emitted from detector, describe relation for corresponding errors in measurements, present two modified biased detectors which avoid these errors.
In this article second Navier -Stokes (NSE) exact transformation to the simpler equations is covered.This executed by classical methods of Mathematical Analysis.It shown that 3-D NSE can be conversed a traditional vector form which looks like 2-D Vorticity Transport Equations.Second result, as well first one, very important for solution Navier-Stokes existence and smoothness one seven Millennium Prize Problems were stated Clay Mathematics Institute.The proof solution' such than NSE.New will...
The additional equalities (additional differential equations) for the Navier -Stokes and other vector PDE are established in this paper.These equations obligatory requirements (properties) of three functions forming a field on Euclidean space.Therefore all solutions should satisfy these requirements.Without Navier-Stokes with so called continuity equation underdetermined as system any "exact solution" is not solution true equation.