Radiation of short-wavelength plasma waves is studied in a cold (Te=0.5eV), large (1.2m length, 70 cm diameter), uniform, Maxwellian laboratory magnetoplasma in the upper-hybrid frequency range. Although the characteristic parameter of spatial dispersion b2=VTe2/c2 is very small (b2<10-6), dispersion characteristics of the upper hybrid plasma waves is found to be strongly modified by the thermal motion of plasma electrons. Indeed, the resonance cone-like dispersion of UH plasma waves has been observed only if the parameter range satisfies simultaneously two inequalities: wc<w<2wc, wp<w<wuh. In this parameter range, the maximal refractive index in the resonant directions has been found to be limited by nmax~15; new UH mode with its dispersion determined by conical refraction has been found in the vicinity of the upper hybrid resonance (w=wuh). Wave dispersion at w<2wc, wp<w<wuh does not correspond to the cold plasma approximation and is determined by thermal plasma waves propagating along the ambient magnetic field. Special attention is given to the wave propagation characteristics in the vicinity of the electron cyclotron resonance. An interesting effect of reduced electron cyclotron damping has been observed when two electromagnetic waves (w1=wc, w2=wc+Dw) propagate simultaneously with Dw approximately equal to the lower hybrid frequency. This effect can be explained as a three-wave parametric process, analogous to the effect of electromagnetically induced transparency in three-level atomic system. Reduced electron cyclotron damping is extensively studied as a function of the beat frequency and the amplitude of the pump wave. Possible applications of the observed effect in plasma physics and electronics are discussed.
Based on the magnetohydrodynamics (MHD) model, an exact arbitrary-amplitude general solution is presented for oblique propagation of solitary excitations in two- and three-component quasineutral magnetoplasmas, adopting the standard pseudopotential approach. It is revealed that the necessary matching criterion of existence of such oblique nonlinear propagations in two and three-fluid magnetoplasmas share global features. These features are examined for the cases of electron-ion and electron-positron-ion magnetoplasmas with diverse equations of state. This study also reveals that for electron-i…
The theory of low-frequency (in comparison with the ion cyclotron frequency), long wavelength, electrostatic drift ion-acoustic waves (IAWs) is studied in a nonuniform rotating magnetoplasma with two temperature superthermal electrons. In the linear limit, the coupling of IAWs and drift waves by the density inhomogeneity is shown to produce a new wave mode which typically depends on the density gradient, the rotational frequency and the spectral indexes of superthermal electrons. In the nonlinear regime, an evolution equation for the drift IAWs is derived by the dispersion approach, and using …
Nonlinear interactions involving electrostatic upper-hybrid (UH), ion-cyclotron (IC), lower-hybrid (LH), and Alfven waves in quantum magnetoplasmas are considered. For this purpose, the quantum hydrodynamical equations are used to derive the governing equations for nonlinearly coupled UH, IC, LH, and Alfven waves. The equations are then Fourier analyzed to obtain nonlinear dispersion relations, which admit both decay and modulational instabilities of the UH waves at quantum scales. The growth rates of the instabilities are presented. They can be useful in applications of our work to diagnostic…
A simulation study of the magnetic electron drift vortex (MEDV) mode turbulence in a magnetoplasma in the presence of inhomogeneities in the plasma temperature and density, as well as in the external magnetic field, is presented. The study shows that the influence of the magnetic field inhomogeneity is to suppress streamer-like structures observed in previous simulation studies without background magnetic fields. The MEDV mode turbulence exhibits non-universal (non-Kolmogorov type) spectra for different sets of the plasma parameters. In the presence of an inhomogeneous magnetic field, the spec…
The behaviour of a strongly-magnetized collisional electron-positron plasma which is optically thin to cyclotron radiation is considered, and the distribution functions accessible to it on the various timescales in the system are calculated. Particular attention is paid to the limit in which the collision time exceeds the radiation emission time, making the electron distribution function strongly anisotropic. Indeed, these are the exact conditions likely to be attained in the first laboratory electron-positron plasma experiments currently being developed, which will typically have very low den…
Zebra-like patterns have been observed in the electron cyclotron emission spectra from strongly nonequilibrium plasma confined in a table-top mirror magnetic trap. The analysis of the experimental data suggests that the formation of zebra-like patterns could eventually be related to modulation of the whistler waves by the ion-acoustic waves excited during the abrupt ejection of electrons into a loss cone caused by the development of the whistler instability under the electron cyclotron resonance condition.
Plasmas created by high-intensity lasers are often subject to the formation of kinetic-streaming instabilities, such as the Weibel instability, which lead to the spontaneous generation of high-amplitude, tangled magnetic fields. These fields typically exist on small spatial scales, i.e. "sub-Larmor scales". Radiation from charged particles moving through small-scale electromagnetic (EM) turbulence has spectral characteristics distinct from both synchrotron and cyclotron radiation, and it carries valuable information on the statistical properties of the EM field structure and evolution. Consequ…
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 …
Radiation damping of the motion of charged particles in relativistic, optically thin plasmas is described within the framework of the covariant gyrokinetic theory. It involves description of the collisionless single-particle dynamics as well as the Vlasov and Maxwell equations both written in the covariant formulation. The damping causes corrections to the phase-space trajectory of the particle, as well as to the form of the kinetic equation itself, due to the failure of conditions of the Liouville theorem. Both effects result independent of the gyrophase, which is retained as an ignorable var…
Plasmas have been recently studied as topological materials. However, a comprehensive picture of topological phases and topological phase transitions in cold magnetized plasmas is still missing. Here we systematically map out all the topological phases and establish the bulk-edge correspondence in cold magnetized plasmas. We find that for the linear eigenmodes, there are 10 topological phases in the parameter space of density $n$, magnetic field $B$, and parallel wavenumber $k_{z}$, separated by the surfaces of Langmuir wave-L wave resonance, Langmuir wave-cyclotron wave resonance, and zero ma…
Fundamental studies of excitation and non-linear evolution of kinetic instabilities of strongly nonequlibrium hot plasmas confined in open magnetic traps suggest new opportunities for fine-tuning of conventional electron cyclotron resonance (ECR) ion sources. These devices are widely used for the production of particle beams of high charge state ions. Operating the ion source in controlled turbulence regime allows increasing the absorbed power density and therefore the volumetric plasma energy content in the dense part of the discharge surrounded by the ECR surface, which leads to enhanced bea…
The Large Volume Plasma device(LVPD), a cylindrically shaped, linear plasma device of dimension( $ϕ=2m $, $ L =3m $) have successfully demonstrated the excitation of Electron Temperature Gradient(ETG) turbulence[ Mattoo et al.,[1]]. The observed ETG turbulence shows significant power between $ω\sim (25-90 krad/s )> Ω_{ci}(= 8 krad/s )$, corresponding to the wavenumber, $ k_y ρ_e ~ (0.1- 0.2)$ where, $ Ω_{ci}$ and $ρ_e(=5 mm ) $, ion cyclotron frequency and electron Larmor radius, respectively. The observed frequency and wave number matches well with theoretical estimates corresponding to Whist…
The Madison plasma dynamo experiment (MPDX) is a novel, versatile, basic plasma research device designed to investigate flow driven magnetohydrodynamic (MHD) instabilities and other high-$β$ phenomena with astrophysically relevant parameters. A 3 m diameter vacuum vessel is lined with 36 rings of alternately oriented 4000 G samarium cobalt magnets which create an axisymmetric multicusp that contains $\sim$14 m$^{3}$ of nearly magnetic field free plasma that is well confined and highly ionized $(>50\%)$. At present, 8 lanthanum hexaboride (LaB$_6$) cathodes and 10 molybdenum anodes are inserted…
Using the extended Poincaré-Lighthill-Kuo (PLK) reductive perturbation method, which incorporates the phase-shift variations, it is shown that common features on propagation and head-on collisions of ion-acoustic waves exist for a magnetized plasmas of different inertial-less particle distributions. For instance it is remarked that, the soliton amplitude is always independent of magnetic field strength while strictly depends on its angle regarding the propagation direction. Both types of solitons (compressive or rarefactive) are shown to exist which are defined through the critical angle $γ=π/…
Magnetized high-energy-density plasmas can often have strong electromagnetic fluctuations whose correlation scale is smaller than the electron Larmor radius. Radiation from the electrons in such plasmas, which markedly differs from both synchrotron and cyclotron radiation, and their energy and pitch-angle diffusion are tightly related. In this paper, we present a comprehensive theoretical and numerical study of the particles' transport in both cold, "small-scale" Langmuir and Whistler-mode turbulence and its relation to the spectra of radiation simultaneously produced by these particles. We em…
We investigate the propagation characteristics of electrostatic waves in a magnetized pair-ion plasma with immobile charged dusts. It is shown that obliquely propagating (OP) low-frequency (in comparison with the negative-ion cyclotron frequency) long-wavelength "slow" and "fast" modes can propagate, respectively, as dust ion-acoustic (DIA) and dust ion-cyclotron (DIC)-like waves. The properties of these modes are studied with the effects of obliqueness of propagation $(θ)$, the static magnetic field, the ratios of the negative to positive ion masses $(m)$ and temperatures $(T)$ as well as the…
Reaching gigagauss magnetic fields opens new horizons both in atomic and plasma physics. At these magnetic field strengths, the electron cyclotron energy $\hbarω_{c}$ becomes comparable to the atomic binding energy (the Rydberg), and the cyclotron frequency $ω_{c}$ approaches the plasma frequency at solid state densities that significantly modifies optical properties of the target. The generation of such strong quasistatic magnetic fields in laboratory remains a challenge. Using supercomputer simulations, we demonstrate how it can be achieved all-optically by irradiating a micro-channel target…
Electric field measurement in plasmas permits quantitative comparison between the experiment and the simulation in this study. An electro-optic (EO) sensor based on Pockels effect is demonstrated to measure wave electric fields in the laboratory magnetosphere of the RT-1 device with high frequency heating sources. This system gives the merits that electric field measurements can detect electrostatic waves separated clearly from wave magnetic fields, and that the sensor head is separated electrically from strong stray fields in circumference. The electromagnetic waves are excited at the double …
Torsional Alfven Oscillation in the Regime of Firehose Instability as a Mechanism of Plasma Stratification in a Laboratory Experiment on Modeling a Coronal Arch
A. V. Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences（俄罗斯科学院阿·瓦·加蓬诺夫-格列霍夫应用物理研究所）；Lobachevsky University（罗巴切夫斯基大学）
Firewall effect on electron acceleration by R-waves and parallel electric fields
Pohang University of Science and Technology（浦项科技大学）；Asia Pacific Center for Theoretical Physics（亚太理论物理中心）；Pohang Accelerator Laboratory, Pohang University of Science and Technology（浦项加速器实验室，浦项科技大学）；Division of Advanced Nuclear Engineering, Pohang University of Science and Technology（先进核工程系，浦项科技大学）
Plasma emission (PE), i.e., electromagnetic radiation at the plasma frequency and its second harmonic, is a general process occurring in both astrophysical and laboratory plasmas. The prevailing theory presents a multi-stage process attributed to the resonant coupling of beam-excited Langmuir waves with ion-acoustic waves. Here we examine another possibility of the fundamental PE induced by the resonant coupling of Z-mode and whistler (W) waves. Earlier studies have been controversial in the plausibility and significance of such process in plasmas. In this study we show that the matching condi…
The measurement of the electron energy distribution (EED) of electrons escaping axially from a minimum-B electron cyclotron resonance ion source (ECRIS) is reported. The experimental data were recorded with a room-temperature 14 GHz ECRIS at the JYFL accelerator laboratory. The electrons escaping through the extraction mirror of the ion source were detected with a secondary electron amplifier placed downstream from a dipole magnet serving as an electron spectrometer with 500 eV resolution. It was discovered that the EED in the range of 5 - 250 keV is strongly non-Maxwellian and exhibits severa…
The electron beam-plasma system is ubiquitous in the space plasma environment. Here, using a Darwin particle-in-cell method, the excitation of electrostatic and whistler instabilities by a gyrating electron beam is studied in support of recent laboratory experiments. It is assumed that the total plasma frequency $ω_{pe}$ is larger than the electron cyclotron frequency $Ω_e$. The fast-growing electrostatic beam-mode waves saturate in a few plasma oscillations by slowing down and relaxing the electron beam parallel to the background magnetic field. Upon their saturation, the finite amplitude ele…
Magnetic reconnection (MR) plays a fundamental role in plasma dynamics under many different conditions, from space and astrophysical environments to laboratory devices. High-resolution in-situ measurements from space missions allow to study naturally occurring MR processes in great detail. Alongside direct measurements, numerical simulations play a key role in investigating the fundamental physics underlying MR. The choice of an adequate plasma model to be employed in numerical simulations, while also compromising with their computational cost, is crucial to efficiently address the problem. We…
It is shown that in low-beta, weakly collisional plasmas, such as the solar corona, some instances of the solar wind, the aurora, inner regions of accretion discs, their coronae, and some laboratory plasmas, Alfvénic fluctuations produce no ion heating within the gyrokinetic approximation, i.e., as long as their amplitudes (at the Larmor scale) are small and their frequencies stay below the ion Larmor frequency (even as their spatial scales can be above or below the ion Larmor scale). Thus, all low-frequency ion heating in such plasmas is due to compressive fluctuations ("slow modes"). Because…
