arXiv subjects

V. S. Mikhailenko

Publications and source records attributed to V. S. Mikhailenko.

At least 19 recordsLinked to original sources

arXiv2026

Parametric instabilities of the inhomogeneous near SOL tokamak plasma, driven by the coupled effect of the high harmonic fast wave and of the ion and electron temperatures gradients, and anomalous heating of the near SOL ions

Electrostatic parametric instabilities in the inhomogeneous near-SOL tokamak plasma, driven by the combined action of a high-harmonic fast wave (HHFW) with a frequency near the 30th ion-cyclotron (IC) harmonic and electron and ion temperature gradients, are investigated numerically. The results indicate the parametric decay of the HHFW into a HHIC (Bernstein) wave and HHIC quasimode. The instability is found to exist within a finite wavelength range of the HHFW. The development of the parametric HHIC quasimode decay instability leads to the onset of parametric turbulence accompanied by anisotropic ion heating, with the ion heating rate across the magnetic field significantly exceeding that along the magnetic field.

physics.plasm-ph↗

arXiv2025

The nonmodal kinetic theory of the macroscale convective flows of magnetized plasma, generated by the inhomogeneous microturbulenc

In this paper, we present the nonmodal kinetic theory of the macroscale two-dimensional compressed-sheared non-diffusive convective flows of a magnetized plasma generated by the inhomogeneous microturbulence. This theory bases on the two-scales approach to the solution of the Vlasov-Poisson system of equations for magnetized plasma, in which the self-consistent evolution of the plasma and of the electrostatic field on the microscales, commensurable with the wavelength of the microscale instabilities and of the ion gyroradius, as well as on the macroscales of a bulk of plasma, is accounted for. It includes the theory of the formation of the macroscale spatially inhomogeneous compressed-sheared convective flows by the inhomogeneous microturbulence, the theory of the back reaction of the macroscale convected flows on the microturbulence, and of the slow macroscale responce of a bulk of plasma on the development of the compressed-sheared convective flows.

physics.plasm-ph↗

arXiv2023

Non-modal kinetic theory of the stability of the compressed-sheared plasma flows generated by the inhomogeneous microscale turbulence in the tokamak edge plasma

A nonmodal kinetic theory of the stability of the two-dimensional compressed-sheared mesoscale plasma flows, generated by the radially inhomogeneous electrostatic ion cyclotron parametric microturbulence in the pedestal plasma with a sheared poloidal flow, is developed. This theory reveals that the separate spatially uniform Fourier modes of the electrostatic responses of the ions and of the electrons on the mesoscale convective flows are determined only in the frames of references moved with velocities of the ion and electron convective flows. In the laboratory frame, these modes are observed as the compressed-sheared modes with time dependent wave numbers. The integral equation, which governs the separate Fourier mode of the electrostatic potential of the plasma species responses on the mesoscale convective flows, is derived. In this equation, the effects of the compressing and shearing of the convective flows are revealed as the time dependence of the finite ion Larmor radius effect. The solution of this equation for the kinetic drift instability displays the nonmodal transformation of the potential to the zero frequency cell-like perturbation when time elapsed.

physics.plasm-ph↗

arXiv2022

The ion acoustic instability of the cylindrical inhomogeneous helicon discharge plasma with rotating electrons

The kinetic theory of the microinstabilities of a cylindrical plasma, produced by the cylindrical azimuthally symmetric (azimuthal mode number $m_{0}=0$) helicon wave, is developed. This theory is based on the derived linear integral equation for the Fourier-Bessel transform of the electrostatic potential, which accounts for the plasma response on the macroscale radial inhomogeneity of the helicon wave, which is commensurable with radial scale of the plasma density inhomogeneity, and on the microscale, which is commensurable with the thermal Larmor radius of electrons. The developed theory reveals new macroscale effect of the azimuthal steady rotation of electrons with a radially inhomogeneous angular velocity, caused by the radial inhomogeneity of the helicon wave. The solution of the integral equation for the electrostatic potential, derived in the short-wavelength limit, is derived in the form of the the functional equation for the electrostatic potential, coupled with infinite number of its satellites at a frequency separation equal to the frequency of the helicon wave. It is the basic equation for the investigations of the dispersion properties of the parametric and current driven instabilities of the cylindrical plasma in the radially inhomogeneous helicon wave. The analytical solution of the derived dispersion equation is found for the high frequency kinetic ion acoustic instability of the cylindrical helicon plasma, driven by the coupled effect of the electron diamagnetic drift and of the steady azimuthal rotation of electrons relative to the ions with a radially inhomogeneous angular velocity.

physics.plasm-ph↗

arXiv2022

Anomalous convective transport of the tokamak edge plasma, caused by the inhomogeneous ion cyclotron parametric turbulence

In this paper, we develop the kinetic and hydrodynamic theories of the convective mesoscale flows driven by the spatially inhomogeneous electrostatic ion cyclotron parametric microturbulence in the pedestal plasma with a sheared poloidal flow. The developed kinetic theory predicts the generation of the sheared poloidal convective flow, and of the radial compressed flow with radial flow velocity gradient. The developed hydrodynamic theory of the convective flows reveals the radial compressed convective flow as the dominant factor in the formation of the steep pedestal density profile with density gradient exponentially growing with time. This gradient density growth is limited by the formation of the radial oscillating with time ion outflow of pedestal plasma to scrape-off layer.

physics.plasm-ph↗

arXiv2022

The ion acoustic instability of the rotating cylindrical helicon discharge plasma

The kinetic theory for the cylindrical plasma, produced by the cylindrically symmetric (azimuthal mode number m=0) helicon wave, is developed with accounting for the cylindrical geometry and the radial inhomogeneity of the helicon wave and plasma. This theory reveals macroscale effect of the azimuthal steady rotation of electrons with a radially inhomogeneous angular velocity, caused by radial inhomogeneity of the helicon electric field. It is found that this sheared rotation as well as the electron density and temperature inhomogeneity are responsible for the development of the high frequency ion acoustic instability of the inhomogeneous cylindrical plasma. This instability is spatially localized in the region of strong gradients of the helicon wave electric field and of the plasma density, where it is more stronger than the parametric instabilities driven by the oscillating motion of the electrons relative to ions in the helicon wave.

physics.plasm-ph↗

arXiv2021

The ion cyclotron parametric turbulence and anomalous convective transport of the inhomogeneous plasma in front of the fast wave antenna

The theory of the ion cyclotron (IC) electrostatic parametric instabilities of the inhomogeneous plasma which are driven by the inhomogeneous electric field of the fast wave (FW) in front of FW antenna is developed. It is found that the spatial inhomogeneity of the parametric IC turbulence and of the drift turbulence is at the origin of the flows which transport a large part of FW power, deposited to the pedestal plasma, to the scrape-off layer and later to the divertor mostly along field lines.

physics.plasm-ph↗

arXiv2020

The ion-acoustic turbulence in the skin layer of the inductively coupled plasma

The theory of the nonmodal ion-acoustic instability in the skin layer of the inductively coupled plasma (ICP) is developed. This instability has time dependent growth rate and is driven by the current formed in the skin layer by the accelerated motion of electrons relative to ions under the action of the ponderomotive force. It is found that the development of the ion acoustic turbulence (IAT) in the skin layer and the scattering of electrons by IAT are basic nonlinear channels of the nonlinear absorption of the RF energy in the skin layer.

physics.plasm-ph↗

arXiv2020

The ion-acoustic instability of the inductively coupled plasma driven by the ponderomotive electron current formed in the skin layer

The stability theory of the inductively coupled plasma (ICP) is developed for the case when the electron quiver velocity in RF wave is of the order of or is larger than the electron thermal velocity. The theory predicts the existence the instabilities of the ICP which are driven by the current formed in the skin layer by the accelerated electrons, which move relative ions under the action of the ponderomotive force.

physics.plasm-ph↗

arXiv2020

Drift-Alfven instabilities of a finite beta plasma sheared flow along a magnetic field with inhomogeneous ion temperature

The drift-Alfven instabilities in the magnetic field aligned (parallel) sheared flow of a finite beta plasma with comparable inhomogeneous ion temperature and homogeneous electron temperature are examined. The development of instabilities are quantitatively discussed on the basis of numerical solution of a set of equations for the electrostatic and electromagnetic potentials. It is found that the accounting for the electromagnetic ion kinetic response, which has been ignored usually in existing discussions of the drift-Alfven instabilities of a steady plasma, reveals new drift-Alfven instability driven by the coupled action of the ion temperature gradient, the flow velocity shear, and the ion Landau damping. The excited unstable waves have the phase velocities along the magnetic field comparable with the ion thermal velocity, and the growth rate comparable with the frequency.

physics.plasm-ph↗

arXiv2020

The parametric instability in the inductively coupled plasma driven by the ponderomotive current

The stability theory of the skin layer plasma of the inductive discharge is developed for the case when the electron quiver velocity in RF wave is of the order of or is larger than the electron thermal velocity. This theory is grounded on the methodology of the oscillating modes, which accounts for the oscillation motion of the electron component relative to the unmovable ions in the spatially inhomogeneous RF field of the skin layer. The theory predicts the existence the instability of the parametric type in a skin layer with the growth rate comparable with frequency. This instability stems from the coupled action of two effects caused by the electron-ion relative motion in RF field: occurrence of harmonics of the perturbed potential and their coupling due to the ponderomotive current. The instability exists in the finite interval of the ponderomotive current velocity and is absent in the uniform boundless plasma.

physics.plasm-ph↗

arXiv2020

Interaction of the fast wave with a scrape-off layer plasma in tokamaks. The ion cyclotron parametric instabilities and the anomalous heating of ions

The theory of the ion cyclotron (IC) electrostatic parametric instabilities of plasma which are driven by the elliptically polarized fast wave (FW) of the finite wavelength is developed. The growth rate of the IC quasimode decay instability, which was considered as a potential source of the generation of the high energy ions in scrape-off layer (SOL) during FW injection in tokamaks, is derived analytically for arbitrary values of the FW electric field and wavelengths of the unstable IC perturbations. The comprehensive numerical analysis of the dispersion equation for three wave system which contains the IC mode $φ_{i}\left(\mathbf{k}_{i}, ω\right)$ and its harmonics $φ_{i}\left(\mathbf{k}_{i}, ω-ω_{0}\right)$, $φ_{i} \left(\mathbf{k}_{i}, ω-2ω_{0}\right)$, where $ω_{0}$ is FW frequency, is performed. It reveals that the parametric IC instability for this wave system has the maximum growth rate for the IC waves with wavelength comparable with the thermal ion Larmor radius. It is found that the inverse electron Landau damping plays essential role in the development of this instability. The possible mechanism of the saturation of this instability is the scattering of ions by the ensemble of the IC waves with random phases, which limits the development of the instability on the high level. The anomalous heating rates of ions resulted from the interactions of ions with parametric IC turbulence is determined employing the developed quasilinear theory for the IC quasimode decay instability. The derived results reveals, that the experimentally observed anisotropic heating of cold SOL ions may be caused by the parametric IC turbulence in SOL. However, the IC parametric turbulence is unlikely to be responsible for the experimentally observed bursts of poorly confined suprathermal ions in the SOL of tokamak plasmas.

physics.plasm-ph↗

arXiv2019

The nonmodal kinetic theory for the electrostatic instabilities of a plasma with a sheared Hall current

The kinetic theory for the instabilities driven by the Hall current with a sheared current velocity, which has the method of the shearing modes or the so-called non-modal approach as its foundation, is developed. The developed theory predicts that in the Hall plasma with the inhomogeneous electric field, the separate spatial Fourier mode of the perturbations is determined in the frame convected with one of the plasma components. Because of the different shearing of the ion and electron flows in the Hall plasma, this mode is perceived by the second component as the Doppler-shifted continuously sheared mode with time-dependent wave numbers. Due to this effect, the interaction of the plasma components forms the nonmodal time-dependent process, which should be investigated as the initial value problem. The developed approach is applied to the solutions of the linear initial value problems for the hydrodynamic modified two-stream instability and the kinetic ion-sound instability of the plasma with a sheared Hall current with a uniform velocity shear. These solutions reveal that the uniform part of the current velocity is responsible for the modal evolution of the instability, whereas the current velocity shear is the source of the development of the nonmodal instability with exponent growing with time as $\sim\left(t-t_0\right)^3$.

physics.plasm-ph↗

arXiv2018

Non-modal Simon-Hoh instability of a plasma with a shearing Hall current

A new analytical nonmodal approach to investigate the plasma instabilities driven by the sheared current is presented and applied to the analysis of the linear evolution of the Simon-Hoh (S-H) instability of a plasma in the inhomogeneous electric field. We found analytically strong nonmodal growth for this instability which is missed completely in the normal modes analysis but dominates the normal mode growth when the shearing rate of the current velocity is above the growth rate of the S-H instability with uniform current. It includes also the nonmodal growth for the subcritical perturbations, which are suppressed in plasma with uniform Hall current.

physics.plasm-ph↗

arXiv2013

The temporal evolution of the kinetic drift-Alfven instability of plasma shear flow

The linear non-modal kinetic theory of the kinetic drift-Alfven instability of plasma shear flows reveals the temporal non-modal growth with growing with time growth rate. The turbulent scattering of the sheared modes on ions accelerates this growth. The instability ceases its growth when the coupling of the drift and Alfven waves violates due to the changing with time frequencies of the drift and Alfven waves in shear flow.

physics.plasm-ph↗

arXiv2012

Non-modal kinetic theory of the hydrodynamic drift instabilities of plasma shear flows

The non-modal kinetic theory of the kinetic drift instability of plasma shear flows [Phys.Plasmas, 18, 062103 (2011)] is extended to the investigation of the long-time evolution of the hydrodynamic ion temperature gradient and resistive drift instabilities in plasma shear flow. We find, that these hydrodynamic instabilities passed in their temporal evolution in shear flow through the kinetic stage of the evolution. In linear theory, this evolution involves the time dependent, due to flow shear, effects of the finite Larmor radius, which resulted in the non-modal effect of the decrease with time the frequencies and the growth rates of the instabilities.

physics.plasm-ph↗

arXiv2012

Non-modal analysis of the diocotron instability. Plane geometry

The comprehensive investigation of the temporal evolution of the diocotron instability of the plane electron strip on the linear stage of its development is performed. By using the Kelvin's method of the shearing modes we elucidate the role of the initial perturbations of the electron density, which is connected with problem of the continuous spectrum. The linear non-modal evolution process, detected by the solution of the initial value problem, leads towards convergence to the phase-locking configuration of the mutually growing normal modes.

physics.plasm-ph↗

arXiv2011

Diffusive instability of a Townsend discharge

The role of the electron diffusion on the stability of a Townsend discharge is investigated. It is obtained, that electron diffusion modifies the condition of the steady self-sustenance of the discharge, and make discharge unstable.

physics.plasm-ph↗