M. E. Viktorov

Laboratory study of kinetic instabilities in a nonequilibrium mirror-confined plasma

Kinetic instabilities of nonequilibrium plasma heated by powerful radiation of gyrotron in electron cyclotron resonance conditions and confined in a mirror magnetic trap are reported. Instabilities are manifested as the generation of short pulses of electromagnetic radiation accompanied by precipitation of hot electrons from magnetic trap. Measuring electromagnetic field with high temporal resolution allowed to observe various dynamic spectra of electromagnetic radiation related to at least five types of kinetic instabilities. This paper may be of interest in the context of a laboratory modeling of nonstationary wave-particle interaction processes in nonequilibrium space plasma since the observed phenomena have much in common with similar processes occurring in the magnetosphere of the Earth, planets, and in solar coronal loops.

Interpretation of complex patterns observed in the electron-cyclotron instability of a mirror confined plasma produced by an ECR discharge

A specific nonlinear regime of electron-cyclotron instability is discussed aimed at explaining the complex temporal patterns of stimulated electromagnetic radiation from a mirror trap with a non-equilibrium plasma typical of an ECR discharge. This regime is characterized by self-modulation of a plasma cyclotron maser due to coherent interference of two counter-propagating unstable waves with degenerate frequencies resulting in the spatial modulation of the amplification coefficient. The proposed simple theoretical model allows one to reproduce the multi-scale time behavior of quasiperiodic pulses of electromagnetic radiation and related precipitation of energetic electrons detected in a laboratory setup based on a magnetic mirror trap with a plasma sustained by mm-wave gyrotron radiation.

Kinetic instabilities in a mirror-confined plasma sustained by high-power microwave radiation

This paper summarizes the studies of plasma kinetic instabilities in the electron cyclotron frequency range carried out over the last decade at the Institute of Applied Physics of Russian Academy of Sciences. We investigate the nonequilibrium plasma created and sustained by high-power microwave radiation of a gyrotron under the electron cyclotron resonance condition. Resonant plasma heating results in the formation of at least two electron components, one of which, more dense and cold, determines the dispersion properties of the high-frequency waves, and the second, a small group of energetic electrons with a highly anisotropic velocity distribution, is responsible for the excitation of unstable waves. Dynamic spectra and the intensity of stimulated electromagnetic emission are studied with high temporal resolution. Interpretation of observed data is based on the cyclotron maser paradigm, in this context, a laboratory modeling of non-stationary wave-particle interaction processes have much in common with similar processes occurring in the magnetosphere of the Earth, planets, and in solar coronal loops.

Monocrystalline InN Films Grown at High Rate by Organometallic Vapor Phase Epitaxy with Nitrogen Plasma Activation Supported by Gyrotron Radiation

InN hexagonal monocrystalline films were grown on yttria-stabilized zirconia (YSZ) (111) and Al2O3(0001) by the organometallic vapor phase epitaxy method with nitrogen activation in the electron cyclotron resonance discharge, supported by gyrotron radiation. The film growth rate reached 10 µm/h. In this paper, we present data on the morphology, structure, and photoluminescence properties of the grown films.

An experimental setup for studying the interaction of dense supersonic plasma flows with an arched magnetic field

We propose a new experimental approach to laboratory investigations of the interaction of supersonic (ionic Mach number up to 2.7) high-density (up to 1015 cm–3) plasma flows and inhomogeneous magnetic field (up to 3.3 T in magnetic mirrors of arched magnetic trap). This approach offers wide possibilities for modeling processes taking place in both near-Earth and space plasma.

Indium Nitride Film Growth by Metal Organic Chemical Vapor Deposition with Nitrogen Activation in Electron Cyclotron Resonance Discharge Sustained by 24 GHz Gyrotron Radiation

We report the results of the first experiments on the growth of indium nitride films by electron cyclotron resonance plasma-enhanced metal organic chemical vapor deposition. Discharge sustained by the radiation of a technological gyrotron with a frequency of 24 GHz and power up to 5 kW was used to provide active nitrogen flow. The use of higher frequency microwave radiation for plasma heating provides a higher plasma density, and more active nitrogen flow. Mirror-smooth homogeneous hexagonal InN films were grown on ittria-stabilized zirconia and sapphire substrates. It was shown that single-crystal InN films can be grown on Al2O3 (0001) substrates if a double buffer layer of InN/GaN is used. The growth rate of 1 µm/h was demonstrated in this case. Film properties are studied by optical and electron microscopies, secondary ion mass spectroscopy, X-ray diffraction, and photoluminescence.

Generation of electromagnetic radiation under double plasma resonance condition in a mirror-confined plasma produced by ECR discharge

Study of kinetic instabilities of non-equilibrium plasma produced in an open magnetic trap by powerful microwave radiation under electron cyclotron resonance (ECR) conditions is of fundamental interest including prospects to simulate physical processes in the solar corona, in the magnetospheres of the Earth and other planets. For example, plasma instabilities in magnetic traps on the Sun are the sources of powerful broadband radio emission (the so-called type IV bursts) which is interpreted as the excitation of plasma waves by fast electrons in the upper hybrid resonance frequency followed by transformation in electromagnetic waves, for example, as a result of scattering by thermal ions. In the case of double plasma resonance condition when the frequency of the upper hybrid resonance coincides with one of the electron gyrofrequency harmonics the instability increment of plasma waves is greatly increased. This leads to the appearance of bright narrow-band radio emission near the harmonics of the electron gyrofrequency - the so-called zebra patterns. It should be noted that the possible manifestations of double plasma resonance effect are not rare in astrophysical plasmas. The phenomenon of zebra pattern is observed not only on the Sun, but in the decametric radiation of the Jupiter, kilometric radiation of the Earth and even in the radio emissions of pulsars. In connection with the above, verification of the effect of double plasma resonance in a laboratory plasma experiments is a very relevant task.