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During the last decade a new probe design for active plasma resonance spectroscopy, the multipole resonance probe (MRP), was proposed, analyzed, developed, and characterized in two different designs: the spherical MRP (sMRP) and the planar MRP (pMRP). The advantage of the latter is that it can be integrated into the chamber wall and can minimize the perturbation of the plasma. Both designs can be applied for monitoring and control purposes of plasma processes for industrial applications. As usual for this measurement technique, a mathematical model is required to determine plasma parameter (electron density, electron temperature, and collision frequency of electrons with neutral atoms) from the measured resonances. Based on the cold plasma model a simple relationship between the resonance frequency and the electron density can be derived and leads to excellent measurement results. However, a simultaneous measurement of the electron temperature in low-pressure plasmas requires a kinetic model, because the half-width of the resonance peak is broadened by kinetic effects. Such a model has been derived and first results show the broadening of the spectra as expected. Deriving a relation between the half-width and the electron temperature will allow the simultaneous measurement and an improvement of monitoring and control concepts.

In this article, we examine the possible influence of the hemispheric sunspot areas (SSAs) on the interplanetary plasma parameters. For this purpose, the daily data of hemispheric SSAs, interplanetary magnetic field, magnitude (B), plasma density (n), plasma velocity (V), plasma temperature (T), and plasma dynamic pressure (P) during the period, 1967–2017, have been used. A long-term relationship between the SSAs and each interplanetary plasma parameter has been identified, if and only if, both SSAs and the daily averages of each interplanetary plasma parameter have been smoothed by a window of a 3-years running average and a specific time-lag has been applied. The daily data of each interplanetary plasma parameter has been classified into two groups, northern (N) and southern (S), based on the dominance of hemispheric SSAs. The absolute asymmetry index (N–S) for each parameter between the northern and the southern sorted group has been calculated. The asymmetry between the northern and the southern sorted groups for each parameter was detected significantly at random years during the entire period. The asymmetry of B over the solar activity cycles is not detectable; indicating that the solar cycles are magnetically symmetric. During the solar cycles 20, 21, and 24, the solar plasma for the southern sorted group was faster (hotter) by 20.3 km/s (15.7 × 103 K), 13 km/s (8 × 103 K), and 29 km/s (14.5 × 103 K) than that of the northern sorted group, respectively. In contrast, during the solar cycle 23, the solar plasma of the southern sorted group was slower (colder) by 7.4 km/s (7.2 × 103 K) than that of the northern sorted one. In addition, the periodic behavior of the N–S asymmetry of the considered solar plasma parameters has been investigated using Fast Fourier Transformation. Many mid- and long-term periodicities have been detected. We present our results and discuss their possible explanations.

The evaluation of the Coulomb logarithm (CL) for different coupled plasma regimes is examined using generalized CL, effective CL, and conventional CL models. To find out the validity and scalability of these models for plasmas in appropriate evaluation of the CL, the classical plasma parameter $${{\Lambda }_{{{\text{cl}}}}}$$ (Coulomb logarithm) is employed. It is observed that the Coupled Gericke–Murillo–Schlanges (CGMS) model can cover better different coupled plasma regimes from weakly to strongly coupled plasmas. The CGMS model has also good agreement with the classical Molecular Dynamics (MD) model in the weakly coupled plasmas and with the generalized Khrapak CL (KH) model in the strongly coupled plasmas. Moreover, the electron–ion relaxation rates for plasmas with different coupling regimes are studied. It is found that the relaxation rates are substantially lower than the classical models predict for the strongly coupled plasmas. We show that the CGMS model is not only compatible with the other models in the weakly coupled plasmas but also almost fitted by the KH model, which is valid in the strongly coupled region.

A nonmagnetized collisional plasma parameter estimator from two frequency signal interrogation attenuation is developed. The plasma parameters that are estimated are the plasma frequency, electron neutral momentum collision frequency, and the plasma thickness. The plasma frequency and electron neutral momentum collision frequency are considered uniform across the plasma thickness. The relative permittivity is defined, and the complex index of refraction is developed. Using this definition and applying the plasma frequency, electron neutral momentum collision frequency, the radial propagation frequency, and plasma thickness, an attenuation is determined for known cases. The development of the estimator is discussed. The estimator uses a performance index where the minimum difference between the plasma frequencies and electron neutral momentum collision frequencies is determined for the two signal interrogation frequencies under the constraint of the same plasma thickness. The estimator was developed in three stages which include iterative, sequential, and adaptive. The setups of the iterative, sequential, and adaptive approaches are discussed. The impact of the interrogation frequency and the estimator setup is investigated. The estimator in the three development stages is compared with known cases and the plasma parameter estimator performance is quantified.

In this experiment, with the help of a Langmuir probe we estimated the plasma parameters at different axial positions inside a multi-dipole magnetic cage. At one end of the multi-dipole magnetic cage, a negatively biased mesh grid is placed. Important plasma parameter such as the electron density, plasma potential and electron temperature are seen to vary significantly towards the grid from the end of the magnetic filter.

The excitation temperature is a widely measured plasma parameter. In this article, the validity of an excitation temperature measurement is verified using a transition simulation between excited levels based on a collisional-radiative model. The collisional-radiative model calculation was validated by comparing it with the results of a spectroscopic measurement for a 2-kA peak vacuum arc ignited between the Cu100, Cu80Cr20, and Cu50Cr50 electrodes, whose diameter and gap length are 10 and 5 mm, respectively. As a result, the experimental result of the spectroscopy can be well simulated using the collisional-radiative model when the electron temperature and electron density are set to approximately 1.1–1.2 eV and 1.3– $2.1\times 10^{20}\,\,\text{m}^{-3}$ , respectively. It was found that the excitation temperature can be obtained from only two lines (510.6- and 515.3-nm lines) of the Cu I spectra with an accuracy comparable to that obtained from many line spectra of Cu neutrals. In addition, the relaxation times of the two lines are shorter than 100 ns. The excitation temperature, the electron temperature, and the electron density of the Cu100 electrodes were slightly higher than those of Cu50Cr50 electrodes. Such dependence on electrode material is caused by the difference in the density of the neutrals and ions. A comparison of the deposition ratio of Cu and Cr on the viewing port glass measured using energy-dispersive X-ray spectroscopy and a comparison of the cathode spot number suggest that the difference in the density of the neutrals and ions is caused by the difference in the cathode spot current.

This study proposed the fluidized particles with dielectric barrier discharge (DBD) plasma in a slot-rectangular divergent-base spouted bed and focused on the dynamics of solid particles with the plasma irradiation. Two bed materials (Polypropylene (PP) particles and Polyamide (PA) particles) with same diameter (3 mm) were fluidized in this study. Fluidization parameters included gas velocity (7.4–14.9 m/s), particle amount (100–500), and plasma parameter (apply voltage, 0 and 7 kV) as the applied voltage were investigated here. Particle velocity profiles were analyzed through the methods of particle image velocimetry (PIV) and particle tracking velocimetry (PTV). Results show that the particle velocity was increased with the plasma irradiation, mainly by the enhancement in the vertical direction. The location of the highest particle velocity area related to the fluidization behavior of particles. With the increase of superficial gas velocity, the location of the highest particle velocity area raised along the central line but not reached the top of the solid bed. While the electron temperature of Ar plasma decreased with the addition of particles. Two electric fields (external electric field and surface charge electric field) presenting in the system were assumed to give the reason for the changes of the particle fluid dynamics.

Laser-induced breakdown spectroscopy (LIBS) is a promising method for the in situ online diagnosis of plasma–wall interaction processes in tokamaks. The effect of gas pressure on the plume expansion and spectral emission of nanosecond laser-induced plasma of the tungsten wall material was systematically investigated using a coaxial optical configuration. A nanosecond pulsed laser (5 ns, 1064 nm) was used to ablate a tungsten target surface to produce plasma at various air pressure levels from 10−3 Pa to 105 Pa. It was found that the plasma size was strongly dependent on the ambient gas pressure, and the plume presented complex behaviors such as free expansion, splitting, sharpening, confinement, etc. The spectral intensity, the signal to background ratio, and signal to noise ratio were also affected significantly by the ambient pressure. The ambient pressure influence on the plasma plume expansion and spectral emission can be ignored when the gas pressure is lower than ∼1 Pa. The pressure of 10–100 Pa and delay time of 200–500 ns were the optimum conditions for the LIBS application in tungsten impurity of tokamak wall diagnosis. Moreover, the ablation-depth results indicated that the depth-resolution of fusion-related material analysis can be controlled by the ambient gas pressure. Temporally-resolved emission measurements were carried out to further investigate the continuum radiation and ionic and atomic emission behaviors. The temporal evolution of the electron density and electron temperature at different pressures was also determined. The plasma parameter change and laser ablation depth reduction were observed which are attributed to the ambient gas confinement and enhanced plasma shielding.

The sputtering of tungsten divertor tiles at the JET ITER-like wall (ILW) during edge-localized modes (ELMs) is one of the main sources of tungsten impurity in the core plasma. The analytical approach for interpretation of the Langmuir probe (LP) measurements of ion flux at the divertor tile is elaborated to model the ELM ion parallel transport and to estimate the flux of sputtered tungsten atoms from the divertor under inter-ELM and intra-ELM conditions. Accounting for the pedestal temperature and density decrease at the pedestal crash during ELM allows obtaining the profiles of the particle and heat fluxes at the divertor tile corresponding to the measurements at the physically correct magnetic connection length. Estimates of the tungsten sputtered flux under intra-ELM and inter-ELM conditions show that first type ELMs contribute significantly (~85%) to the overall tungsten sputtering, which is in a good agreement with the divertor optical emission spectroscopy of the 400.9 nm atomic neutral tungsten line in JET discharges.

A cathode-less radio frequency (RF) thruster is a plasma-based system for space propulsion. It consists on a source for plasma generation driven by an RF antenna and a magnetic nozzle for the acceleration of the exhausted plasma stream. A parametric analysis has been conducted in order to evaluate the influence of some key design parameters on the performances of such a thruster. Specifically, the intensity and the topology of the magneto-static field, along with the antenna geometry have been varied. Their influence has been assessed on the plasma parameter profiles within the source (i.e., electron density, electron temperature, and power deposition), the antenna properties (i.e., impedance and current distribution), and the propulsive performances (i.e., thrust and specific impulse). The results presented in this work have been obtained with the validated code 3D-VIRTUS. The latter solves self-consistently both the electro-magnetic wave propagation and the plasma transport within a source driven by a RF antenna. An analytical model has been subsequently employed in order to solve the plasma dynamics in the plume and, in turn, to estimate the propulsive performances.

A multiple regression and machine learning approach is proposed to solve multiple plasma parameter inversion in complex systems. For an electromagnetic (EM) wave and plasma interaction system, it is common to retrieve plasma parameters based on the reflected or scattered EM field, whereas multiple parameter inversion becomes particularly challenging for anisotropic inhomogeneous plasma medium. Artificial neural network (ANN) is applied to retrieve the plasma density fluctuation in inhomogeneous medium. The method is computationally efficient and robust based solely on time series of data collected at a fixed number of spatial locations. The inversion algorithm opens venues and application for inhomogeneous plasma parameter inversion for EM wave and plasma interaction system at different frequencies.

This work discusses the results of the analysis of the pulsed time structure of X-ray radiation for the SOL1996-07-09T09:09:01, GOES X2.6-class flare recorded by CGRO/BATSE and the numerical simulation of the propagation of accelerated electrons in the plasma of a magnetic loop with a time structure at injection that reflects the structure of hard X-ray radiation. Initially, preliminary processing of the data series was carried out, and the spectral methods of Wavelet and Fourier transforms of X-ray series were then used in energy ranges: 22–56 keV and 56–105 keV. In the time series (22–56 keV and 56–105 keV), the time structures with a duration of ~0.1 to ~1 s are selected; their spectral power exceeds the red-noise level with a probability of 99%. The simulation of the thin time structure of the X-ray radiation of the accelerated electron beam was carried out on the basis of the solution of the kinetic equation for the given plasma parameter distributions and the magnetic field along the flare loop. It is shown that for plasma density values of less than ~1011 cm–3 in the loop top, the structure of hard X-ray radiation in the top does not reflect the millisecond structure of accelerated electrons. A fine structure of hard X-rays can occur in footpoints with a high plasma density (n0 > 1011 cm–3), and more likely with a fairly soft electron spectrum (δ ~ 7) and/or with increasing angular anisotropy in the distribution of accelerated electrons at the time of their injection into the top of the magnetic loop.

A hollow cathode source is designed to generate multiple double layer (MDL) structures by the trapping of charged particles in the absence of any auxiliary plasma source or magnetic field, while the glow discharge switches between two distinctly different stable regimes. The generation and dynamics of localised and intensely luminous MDL formations are experimentally investigated in low-frequency sheath oscillation inhibited glow discharge by modified Langmuir probes in a linear vacuum vessel. The localised complex structures grow axially into visibly glowing coaxial formations along with structural changes in MDL formations, on increasing the applied voltage in nitrogen plasma at 0.1 mbar pressure. The discharge gradually expands to fill up the entire vessel through redistribution of energetic charged particles and formation of multiple sheaths on increasing the applied voltage across the electrodes. The present experimental study reveals interesting information about the formation of the sheath, stability of the plasma sheath and charged particle dynamics during the discharge transformations. The paper relates the plasma parameter variations with the nonlinear time series analysis of the discharge current and floating potential fluctuations through the reconstructed phase space in different discharge domains to analyse the dynamics of MDL formations and harmonic generation through sheath oscillations during the hollow cathode discharge regimes. The radial motion of the charged particles during the glow discharge between the semi-transparent gridded cylindrical cathode and the central anode might be useful for a better understanding of the underlying basic sheath physics related to particle acceleration in plasma as well as application in plasma sputtering.

The information of plasma technologies applications for environmental clean-up on treating and degrading metals, metalloids, dyes, biomass, antibiotics, pesticides, volatile organic compounds (VOCs), bacteria, virus and fungi is compiled and organized in the review article. Different reactor configurations of plasma technology have been applied for reactive species generation, responsible for the pollutants removal, hydrogen and methane production and microorganism inactivation. Therefore, in this review article, the reactive species from discharge plasma are presented here to provide the insight into the environmental applications. The combinations of plasma technology with flux agent and photocatalytic are also given in this review paper associated with the setup of the plasma system on the removal process of metals, VOCs, and microorganisms. Furthermore, the potential of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inactivation via plasma technology is also described in this review paper. Detailed information of plasma parameter configuration is given to support the influence of the critical process in the plasma system to deal with contaminants., Graphical Abstract ga1

Nonlinear electrodynamic (NLED) theories are well motivated for their extensions to classical electrodynamics in the strong field regime, and have been extensively investigated in the search for regular black hole solutions. In this paper, we focus on two spherically symmetric and static black hole solutions based on two types of NLED---the Euler-Heisenberg NLED model and the Bronnikov NLED model---and calculate the weak deflection angle of light and charged particles by these two black holes with the help of the Gauss-Bonnet theorem. We investigate the effects of the one-loop corrections to quantum electrodynamics on the deflection angle and analyze the behavior of the deflection angle by a regular magnetically charged black hole. It is found that both the electric and magnetic charges of the black hole reduce the weak deflection angle, and the one-loop corrections make a positive contribution to the deflection angle, but their influence is deeply suppressed by the impact parameter. For the charged particles, due to electrostatic interaction, the weak deflection angle changes noticeably and the influence of the one-loop corrections is enhanced. We find that the regular magnetically charged black hole based on the Bronnikov NLED model has a smaller deflection angle than the singular one. We also calculate the deflection angle of light by the geodesic method for verification. In addition, we discuss the effects of a cold nonmagnetized plasma on the deflection angle and find that the deflection angle increases with the plasma parameter.

As an important component of space environment, the ionospheric plasma is the main background environment for the operation of low-orbit spacecraft. The study of ionospheric plasma environment parameters and the enrichment of plasma environment data are beneficial to improve the reliability of low-orbit spacecraft operation. Langmuir probe is the most popular method for detecting the plasma parameter of ionospheric, however, it has some defects. In this paper, we design a plasma generator based on radio-frequency discharge to imitate the ionospheric plasma environment, and measure plasma parameter based on Thomson scattering by import a Nd: YAG laser oscillate in the plasma generator. The result demonstrates that the intensity of laser Thomson scattering signal is positively correlated with the change of plasma electron density. The electron density in the plasma generator is calculated according to the laser Thomson scattering signal intensity, and the error is less than 10% compared with that measured by the Langmuir probe.

Plasma diagnosis has done by using Langmuir probe and software modeling. COMSOL and JMAG software were employed to characterize the electron density and identifying the set up effect in the plasma system. First, the COMSOL software was employed to simulate the behavior of electron density. The pressure and DC-bias voltage were varied during the simulation process. The DC bias voltage was varied in the range -200 V to -600V. The pressure was also varied in the range 30 to 80 Pa. The high electron density was generated in the high DC-bias voltage and high pressure by using simulation process. Second, the Langmuir probe was also employed to measure the behavior of electron density inside the actual plasma chamber. The DC-bias voltage and pressure were also varied in the range - 350V to – 650V and 60 Pa to 120 Pa, respectively. The experiment and modeling result were shown the same trend for the behavior of electron density. Third, the JMAG software was also utilized to characterize and modifying the set up in the plasma system. The electrode and DC bias was varied in the range 100 to 500 V and -100 to -500 V, respectively. The electric field distribution was concentrated in the electrode and DC-bias plate from the original set up. However, the electric field distribution was shifted to the center area after modification process. The modifications of experiment set up have provided the new way to confine the electric field. The high concentrated of electric field was effective to generate high plasma density.

Inductively coupled plasma sources driven by RF power at low-pressure regimes are well adopted for high-volume manufacturing of semiconductor devices. One vexing challenge to the utility of these plasma processing reactors is the existence of the E–H-mode transition. Industry notably avoids the process region associated with this transition, where plasma instabilities and bimodal power coupling prohibit reliable RF power delivery. One plasma instability detailed in this paper is associated with a hysteresis in coupled RF power (current) varying for the E-mode, or weakly capacitive coupling to the plasma, in comparison to the stronger current coupling in the H-mode, where inductive coupling is preferentially dominant. As a result, approximately two orders of magnitude of electron density is relinquished in this transition region from serving industrial manufacturing processes. We characterize the plasma parameter variation through the E-mode to H-mode with a time-resolved measurement of the electron density. Electronegative chemistries are incorporated into our experimental setup. The experimental scheme serves to evaluate RF power delivery and ameliorate its coupling through the transition region. We seek to extend this paper to adopt more efficient power coupling for toroidal plasma sources.

The turbulent characteristics of plasma fluctuations in the solar wind (SW) may substantially change depending on the SW conditions. Large-scale streams of different types, such as undisturbed slow solar wind, fast solar wind, interplanetary coronal mass ejection (EJECTA), magnetic cloud (MC), the compression region at the boundary between fast and slow streams (CIR), and the compression region in front of the EJECTA/MC (SHEATH), are usually characterized by specific plasma parameter values, which may influence turbulent cascade formation. In this paper, we analyze the properties of the spectra of ion flux fluctuations in the SW in the region of transition from the magnetohydrodynamic (MHD) scale to the kinetic one. The analysis is based on measurements carried out with the BMSW plasma spectrometer onboard the SPEKTR-R spacecraft with a high time resolution. The observational intervals inside the SW streams of different large-scale types are considered, and the main turbulence characteristics in these streams are compared. It was shown that the properties of the fluctuation spectra may strongly depend on the SW type; in particular, the spectrum of kinetic-scale fluctuations usually becomes much steeper inside the MC regions and the compression regions in front of them, as well as in the CIR. The characteristics of the fluctuation spectra on MHD scale are less dependent on the type of large-scale SW structures, and, on average, they correspond to the Kolmogorov spectra. However, it can be noted that the smallest spectral slopes are observed in the slow undisturbed solar wind, which is indicative of the differences from the traditional Kolmogorov model of the developed turbulence.

The core plasma confinement during detachment phase is investigated in the discharges with application of resonant magnetic perturbation (RMP) field in LHD. The RMP application creates a remnant magnetic island in the edge stochastic layer, which largely changes the plasma parameter profiles including impurity radiation. The electron temperature and pressure profiles are flattened at the island, while the electron density is slightly peaked at the edge of the island. The estimated impurity radiation profile is enhanced and fixed around the magnetic island during the detached phase, where the discharge is stably sustained with controlled level of radiation. Without RMP, the radiation penetrates the confinement region, leading to radiation collapse. It is found that in the case of the RMP application the plasma stored energy increases discontinuously at the detachment transition. In spite of the reduced effective plasma volume caused by the edge magnetic island and by the enhanced radiation there, the central plasma pressure finally exceeds the case without RMP. This is caused by the pressure profile peaking at the central region in the case with RMP. These results indicate clear change of core plasma confinement during the detached phase with RMP.

Impurity flow velocity measurements have been conducted for different magnetic field configurations in a wide plasma parameter range in the divertor leg region of LHD for understanding of the edge impurity transport. In all cases (densities, magnetic configurations, hydrogen (H) & deuterium (D) discharges), flows of several tens of km/s are observed. It is found that the flow in thick stochastic layer is faster than in thin stochastic layer configuration by a factor of 3. Different velocities of different charge states of carbon impurity are observed. The simulation with EMC3-EIRENE code shows similar trend as the experiments, but only qualitatively: faster flow in H compared to D discharges due to the mass effect, faster flow in the case of thick stochastic layer. However, synthetic spectra show discrepancy with experiments in the absolute Doppler shift, where the impurity velocity in the experiments is one order faster compared to the simulations. Keywords: Spectroscopy, Hydrogen, Deuterium, Carbon, Impurity transport, Edge plasma

In this article, we have examined the possible influence of hemispheric solar activity features on the interplanetary plasma parameters. For this purpose, the daily data of sunspot areas (SSAs) and sunspot numbers (SSNs) as well as the interplanetary plasma parameters (interplanetary magnetic field (IMF) magnitude B, plasma density n, plasma velocity V, plasma temperature T, and plasma dynamic pressure P) during the period 1967 2017 have been used. The daily data of each interplanetary plasma parameter has been classified into two groups, northern (N) and southern (S) sorted groups based on the dominance of hemispheric SSAs or SSNs. The yearly averages of the sorted N and S groups have been calculated for each plasma parameter. The asymmetry index (N-S) for each parameter between the northern and the southern sorted group has been calculated. The asymmetry of B over the solar activity cycles is not detectable, indicating that the solar cycles are magnetically symmetric, in agreement with the findings of (El-Borie et al., 2018a). During the solar cycles 20, 21, and 24, the solar plasma for the southern sorted group was faster (hotter) by 20.3 km/s (15.7×103 oK), 13 km/s (8×103 oK), and 29 km/s (14.5×103 oK) than that for the northern sorted group, respectively. In contrast, during the solar cycle 23, the solar plasma for the southern sorted group was slower (colder) by 7.4 km/s (7.2×103 oK) than that for the northern sorted one.

Incoherent scatter (IS) radars are invaluable instruments for ionospheric physics, since they observe altitude profiles of electron density (Ne), electron temperature (Te), ion temperature (Ti) and line‐of‐sight plasma velocity (Vi) from ground. However, the temperatures can be fitted to the observed IS spectra only when the ion composition is known, and resolutions of the fitted plasma parameters are often insufficient for auroral electron precipitation, which requires high resolutions in both range and time. The problem of unknown ion composition has been addressed by means of the full‐profile analysis, which assumes that the plasma parameter profiles are smooth in altitude, or follow some predefined shape. In a similar manner, one could assume smooth time variations, but this option has not been used in IS analysis. We propose a plasma parameter fit technique based on Bayesian filtering, which we have implemented as an additional Bayesian Filtering Module (BAFIM) in the Grand Unified Incoherent Scatter Design and Analysis Package (GUISDAP). BAFIM allows us to control gradients in both time and range directions for each plasma parameter separately. With BAFIM we can fit F1 region ion composition together with Ne, Te, Ti and Vi, and we have reached 4 s/900 m time/range steps in four‐parameter fits of Ne, Te, Ti and Vi in E region observations of auroral electron precipitation.

In the paper, an X-ray spectroscopy-based approach on laser pulse temporal profile characterization is described. The structure of dielectronic satellites to H-like Ly&alpha, lines strongly depends on a plasma electron density, so it can be applied for diagnostics. These spectral lines are mainly emitted during initial stage of laser plasma expansion. It means that plasma parameters obtained via them characterizes matter conditions in a region surrounding a spot of laser-matter interaction. In the case when a laser contrast is high enough, the radiation interacts with cold matter, which had not been preliminary perturbed by a laser prepulse, and the satellites structure shape corresponding to high densities should be observed. It allows us to consider the satellites as a diagnostic tool for the laser temporal profile quality. In the paper dependencies of the dielectronic satellites structure on electron densities obtained from detailed kinetic calculations in the wide range of plasma parameter for different elements are under discussion. Fundamental theoretical aspects of plasma diagnostic based on the feature of satellite structures shape in hot dense plasma, which led to development of the proposed method, are also explained.

59 pages, 24 ref.; We consider a homogeneous plasma composed of N particles of the same electric charge which interact through a Coulomb potential. In the large plasma parameter limit, classical kinetic theories justify that the empirical density is the solution of the Balescu-Guernsey-Lenard equation, at leading order. This is a law of large numbers. The Balescu-Guernsey-Lenard equation is approximated by the Landau equation for scales much smaller than the Debye length. In order to describe typical and rare fluctuations, we compute for the first time a large deviation principle for dynamical paths of the empirical density, within the Landau approximation. We obtain a large deviation Hamiltonian that describes fluctuations and rare excursions of the empirical density, in the large plasma parameter limit. We obtain this large deviation Hamiltonian either from the Boltzmann large deviation Hamiltonian in the grazing collision limit, or directly from the dynamics, extending the classical kinetic theory for plasmas within the Landau approximation. We also derive the large deviation Hamiltonian for the empirical density of N particles, each of which is governed by a Markov process, and coupled in a mean field way. We explain that the plasma large deviation Hamiltonian is not the one of N particles coupled in a mean-field way.

In the direct vicinity of plasma-facing surfaces, the incident plasma particles interact with surface-recombined neutrals. Remarkably high near-surface pressure losses were observed in the high-flux linear plasma generator Magnum-PSI. Combining the incoherent and coherent Thomson scattering diagnostics, we directly measured particle, momentum and energy fluxes down to 3 mm from the plasma target surface. At the surface, the particle and total heat flux were also measured, using respectively an in-target Langmuir probe and thermographic methods. The near-surface momentum and energy losses scale with density, and amount to at least 50 % and 20%, respectively, at ne=8centerdot1020m-3. These losses are attributed to the efficient exchange of charge, momentum and energy between incident plasma and surface-recombined neutrals. In low-temperature plasmas with sufficient density, incident particles go through several cycles of interaction and surface deposition before leaving the plasma, thereby providing an effective alternative dissipation channel to the incident plasma. Parallel plasma parameter profiles exhibit a transition with increasing plasma density. In low-density conditions, the plasma temperature is constant and near-surface ion acceleration is observed, attributed to the ambipolar electric field. Conversely, deceleration and plasma cooling are observed in dense conditions. These results are explained by the combined effect of ion-neutral friction and electron-ion thermal equilibration in the so-called thermalized collisional pre-sheath. The energy available for ambipolar acceleration is thus reduced, as well as the upstream flow velocity. In the ITER divertor, enhanced near-surface p-n interaction is expected as well, given the overlap in plasma conditions. Including these effects in finite-element scrape-off layer models requires a near-surface resolution smaller than the neutral mean free path. This amounts to 1 mm in Magnum-PSI, and possibly an order of magnitude smaller in ITER.

International audience; In low temperature magnetized plasma, Langmuir probe measurements must be corrected because of the electron diffusion through the sheath which is formed around the probe collector. The correction factor which is called the electron diffusion or electron sink parameter depends on many other parameters like the probe geometry, the electron diffusion coefficient, the sheath thickness or the potential profile through the sheath. Based on a previous work, we determine the values of this parameter under different experimental conditions and we study the effect of the electron energy, of the probe biased voltage and of the magnetic field intensity on this parameter. The results are compared with theoretical models published in literature. An empirical equation is determined to fit the diffusion parameter value versus magnetic field intensity.

An investigation has been done to study the effects of κ-distributed electrons on the waves with arbitrary amplitude of magnetized plasma in the presence of warm ions and negatively charged dust particles. The kappa distribution (κ > 3/2), which represents a velocity distribution, contains high energy tail but nears to the Maxwell–Boltzmann distribution as κ → ∞. In this work, by using the non-perturbation technique (i.e., Sagdeev pseudopotential analysis), a suitable mathematical expression for the arbitrary amplitude double layers in dust kinetic Alfven waves is formulated. Using the standard numerical values for different plasma parameter related to it, the Sagdeev Potential (SP) has been calculated for the plasma waves. It is observed that the spatial index κ plays a substantial role in finding the size and shape of double layers. Depth of double layers increases with decreasing kz, keeping ω fixed. For this parameter set, the double layer does not exist when M ≤ 1.1. This theoretical study may be helpful for explaining some of recent in situ observations (e.g., Freja, Cassini) in space plasmas, where one of its constituents is kappa distributed electron.