The distribution of temperature in an expanded thermal plasma jet is investigated by modified Langmuir probes. The validation of classical probe theory in the entire experimental chamber pressure range of 10–100 mbar is thoroughly established before the measurements. The average temperature of the plasma jet at the nozzle exit was also measured by calorimetric estimation of total heat loss from the plasma upstream of that point. A correlation is made using simple analytical expression in between the average temperature measured from the heat loss data and the centerline temperature at the nozzle exit measured by Langmuir probe. The profile parameter n for the radial distribution of temperature in a plasma jet is calculated for different operating current and gas flow rates.

This work is based on a numerical study of particle transport and diffusion using ITER parameters. In particular, the effects of introducing a non-monotonic safety factor (NMSF) in the case of a reversed magnetic shear are shown. These results are compared with those found by using a monotonic safety factor (MSF). Double internal transport barriers are detected influencing the transport and diffusion of particles. The choices of the mode (m, n) and the m/n values play a dominant role for the particle diffusion, which leads to an improvement of the magnetic confinement.

We consider the nonlinear instability of modified Langmuir and ion–sound waves caused by partially coherent photons in dense quantum plasmas. In our model, the dynamics of the photons is governed by a wave kinetic equation. The evolution equations for the Langmuir and ion–sound waves are deduced from the quantum hydrodynamic equations accounting for the incoherent photon pressure, the quantum statistical electron pressure, and the quantum Bohm force acting on the degenerate electrons. The governing equations are Fourier analyzed to obtain nonlinear dispersion relations. The latter are analyzed to predict instability of the modified Langmuir and ion–sound waves in the presence of partially coherent photons. Possible applications of our investigation to the next generation of intense laser–solid dense plasma experiments and compact dense astrophysical bodies are mentioned.

Observations of interstellar scintillations at radio wavelengths reveal a Kolmogorov-like scaling of the electron density spectrum with a spectral slope of −5/3 over six decades in wavenumber space. A similar turbulent density spectrum in the solar wind plasma has been reported. The energy transfer process in the magnetized solar wind plasma over such extended length scales remains an unresolved paradox of modern turbulence theories, raising the especially intriguing question of how a compressible magnetized solar wind exhibits a turbulent spectrum that is a characteristic of an incompressible hydrodynamic fluid. To address these questions, we have undertaken three-dimensional time-dependent numerical simulations of a compressible magnetohydrodynamic fluid describing super-Alfvénic, supersonic and strongly magnetized plasma. It is shown that the observed Kolmogorov-like (−5/3) spectrum can develop in the solar wind plasma by supersonic plasma motions that dissipate into highly subsonic motion that passively convect density fluctuations.

Large amplitude ion-acoustic solitons are treated by a Sagdeev pseudopotential analysis, in a plasma with two adiabatic constituents, with the full inclusion of inertial and pressure effects for both. The sign of the supersonic species determines the polarity of the solitons, which are compressive in both constituents. Emphasis is placed on the determination of the soliton existence domains in compositional parameter space, allowing correct Sagdeev pseudopotential graphs to be easily generated, and offering insight into why limitations occur. Soliton velocities are bounded from below by the true acoustic velocity in the plasma model, and from above by the breakdown of the description when the supersonic ions reach their sonic point. Increases in the mass density ratio and the soliton velocity or decreases in the temperature ratio lead to increases in soliton amplitudes and decreases of the widths. Applications include hydrogen and electron–positron plasmas, and various kinds of dusty plasmas.

Wave magnetic field components are measured across the radius (−10 cm ≤ r ≤ 10 cm) for a low-pressure (0.3 mbar) helicon discharge, in a toroidal vacuum chamber of small aspect ratio. Radial variation of the wave magnetic field components, measured during the helicon mode of the discharge, exhibit strong poloidal asymmetry which contribute significantly to the wave-induced helicity. The rise in the magnitude of the radial electric field with radiofrequency power, observed during discharge mode transition, supports better radial confinement of the plasma during the helicon mode of the discharge. The strong dependence of the plasma current on the helicon mode of the discharge has been observed during the present experimental study.

We describe the spatio-temporal evolution of one-dimensional Alfven resonance disturbance in the presence of various factors of resonance detuning: dispersion and absorption of Alfven disturbance, nonstationarity of large-scale wave generating resonant disturbance. Using analytical solutions to the resonance equation, we determine conditions for forming qualitatively different spatial and temporal structures of resonant Alfven disturbances. We also present analytical descriptions of quasi-stationary and non-stationary spatial structures formed in the resonant layer, and their evolution over time for cases of drivers of different types corresponding to large-scale waves localized in the direction of inhomogeneity and to nonlocalized large-scale waves.

A previous theoretical result on stimulated Brillouin scattering is corrected.

We review the concept of photon effective charge in a plasma, and extend it to the case of longitudinal photons or plasmons. A simple electrostatic fluid model is considered in a non-magnetized and non-relativistic plasma. The contribution of the ions to the plasmon charge is also considered.

The radiation of whistler waves by linear dipole sources immersed in magnetoplasmas with cylindrical magnetic field inhomogeneities are studied. Two types of irregularities are investigated: magnetic field enhancements and depletions. A theoretical analysis is developed for comparatively weak local perturbations of the ambient magnetic field. Results are provided by numerical calculations performed for physical conditions typical of laboratory experiments involving artificially created magnetic field irregularities. It is shown that plasma regions with locally enhanced (depleted) magnetic field intensities can increase (decrease) the amplitudes of whistler waves radiated by dipole sources, regardless of their orientation with respect to the ambient magnetic field. Results are relevant to space and laboratory experiments on very low-frequency wave radiation.

This paper examines the anisotropies of a charged particle beam moving into a linear focusing channel. Considering a high-intensity ion beam in space-charge-dominated regime and large mismatched root mean square (RMS) initial beam size, a fast increase in spatial beam anisotropy is observed. Calculations presented here are strong evidence that this anisotropy is responsible for the beam's equipartition. It is shown that particle–particle resonances and wave-particle resonances lead to anisotropization of the beam, i.e. both the envelope and emittance ratios different from unity. It indicates that this anisotropy is responsible for the beam's equipartitioning and suggest that the beam remains equipartitioned even when exhibiting a macroscopic anisotropy, which is characterized by the following properties: the development of an elliptical shape with increasing size along one axis, the presence of a coupling between transversal emittances and halo formation along a preferential direction.

The Weibel instability, driven by a plasma temperature anisotropy, is non-resonant with plasma particles: it is purely growing in time, and does not oscillate. The effect of a counterstreaming plasma is examined. In a counterstreaming plasma with an excess of transverse temperature, the Weibel instability arises along the streaming direction. Here it is proved that for large wave-numbers the instability becomes resonant with a finite real (oscillation) frequency, ωr ≠ 0. When the plasma flows faster, with a bulk velocity larger than the parallel thermal velocity, the instability becomes dominantly resonant. This new feature of the Weibel instability can be relevant for astrophysical sources of non-thermal emissions and the stability of counterflowing plasma experiments.

The influence of the intrinsic spin of electrons on the propagation of circularly polarized waves in a magnetized plasma is considered. New eigenmodes are identified, one of which propagates below the electron cyclotron frequency, one above the spin-precession frequency, and another close to the spin-precession frequency. The latter corresponds to the spin modes in ferromagnets under certain conditions. In the non-relativistic motion of electrons, the spin effects become noticeable even when the external magnetic field B0 is below the quantum critical magnetic field strength, i.e. B0 < BQ = 4.4138 × 109T and the electron density satisfies n0 ≫ nc ≃ 1032m−3. The importance of electron spin (paramagnetic) resonance (ESR) for plasma diagnostics is discussed.

The appearance of rogue waves is well known in oceanographics, optics, and cold matter systems. Here we show a possibility for the existence of atmospheric rogue waves.

The propagation of intense few-cycle laser beams in plasma media is considered when the quiver velocity of the electron approaches the velocity of light c. The modifications in the spatio-temporal profile of the initial Gaussian beam are found to depend on the combined effect of relativistic plasma frequency and diffraction. The results of the variation of the temporal profile of the envelope at points on the axis as well away from the axis are presented. The results so obtained are compared with those of vacuum propagation. Pulses get broadened and frequency gets chirped as a result of diffraction, phase dispersion and relativistic mass correction. The effect of the plasma on the group velocity dispersion including curvatures of pulse and phase fronts in pulsed Gaussian beam is numerically investigated.

In the HT-7 tokamak, heat transport analysis is carried out for the lower hybrid current drive (LHCD) experiments. Electrons and ions are coupled and good confinement can be obtained by properly optimizating LHCD and plasma parameters. Under the conditions that the plasma current is about 220 kA, the lower hybrid wave (LHW) power is about 300 kW and the central line-averaged density is about 1.5×1013 cm−3, lower hybrid wave power deposition is off-axis. Local transport analysis illustrated that both electron and ion thermal diffusivities are decreased during the LHW phase, and the electron internal transport barriers (eITBs) are formed while been accompanied by the ion internal transport barriers (iITBs) during LHW phase. Ions are heated by electron-ion collision in the region of the barriers although the ohmic power and the LHW power were absorbed by the electrons. Both electron temperature and ion temperature are increased during the LHW phase, and in the confinement region, the electron-to-ion temperature ratio, Te/Ti varies from 2.0 ~ 2.5 during OH phase to 1.3 ~ 1.6 during LHW injected into the plasma, which shows that electron confinement is not degraded by the electron–ion collisions meanwhile ions are also confined. The energy confinement is increased from 13 ms to 25 ms due to the formation of electron and ion internal transport barries after the LHW is injected into the plasma. LHW driven current and bootstrap current contribute to 60% of the total current.

Interaction between dust particles in a plasma is investigated on the basis of experimental pair correlation functions of dust formation in a dc glow discharge and the Poisson equation. It is shown that the calculated effective potentials have an oscillating character and depend rather weakly on macroscopic parameters of the plasma. Existence of an attractive component in the interaction of dust particles is confirmed within the validity range of our model.

Micrometeoroids entering the terrestrial atmosphere lead to two important related electrical effects. One is the electrification of the upper atmosphere along their paths and the other is the electrical charging of the micrometeoroids themselves. In this brief note we will emphasize the central role of the initial encounter speed of the incoming micrometeoroid, showing how it changes the altitude profiles of electron production and electrical charging, not just quantitatively but also qualitatively. We will discuss the underlying reasons for this, as well as their importance in meteor studies.

A hydrodynamic model of two-plasmon decay in a homogeneous plasma slab near the quarter-critical density is utilized to study the spatio-temporal evolution of the daughter electron plasma waves in plasma in the course of the instability. The influence of laser and plasma parameters on the evolution of the amplitudes of the participating waves is discussed, assuming that the secondary coupling of two daughter electron plasma waves with an ion-acoustic wave is the principal mechanism of saturation of the instability. The impact of inherently non-resonant nature of this secondary coupling on the development of TPD is investigated for the first time and it is shown to significantly influence the electron plasma wave dynamics. Its inclusion leads to non-uniformity of the spatial profile of the instability and causes the burst-like pattern of the instability development, which should result in the burst-like hot-electron production in homogeneous plasma.

Through an extended kinetic model, we study the nonlinear generation of quasi-static magnetic fields by high-frequency fields in a plasma, taking into account the effects of the electron spin. It is found that although the largest part of the nonlinear current in a moderate density, moderate temperature plasma is due to the classical terms, the spin may still give a significant contribution to the magnetic field generation mechanism. Applications of our results are discussed.