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An atmospheric-pressure microwave plasma torch is employed to generate hydrogen by injecting methanol aerosols into the near afterglow region of a nitrogen microwave plasma. Two types of reaction chambers are proposed to study the influence of different boundary conditions of reaction chambers on hydrogen production by comparison. Fourier transformation infrared spectrometer and gas chromatography are used to measure and determine the hydrogen production rate, energy efficiency, and hydrogen yield. Also, the effects of conditions of methanol injection and discharge parameters on methanol decomposition are investigated, respectively. It is found that the active species originated from collision with the excited and ionized N2 in the high gas temperature in the plasma discharge plays an important role in the conversion of methanol to hydrogen. The gas flow pattern in the reaction chamber is closely related to boundary conditions and significantly affects the reaction time of methanol in it, which is analyzed with the software of computational fluid dynamics. The achievements of hydrogen production in our work are as follows: production rate up to 921 l/h, energy yield up to 371 l/kWh, and hydrogen yield up to 70%, respectively. Furthermore, the reaction mechanism is discussed in detail with respect to the formation of outlet products. [ABSTRACT FROM AUTHOR]

The surface of Chinese-manufactured T800 carbon fiber (CF) underwent air ICP plasma treatment to enhance its interfacial bonding with polyimide resin at high temperatures. This treatment significantly improved the high-temperature interlaminar shear strength (ILSS) of the CF/PI composite. Optimal treatment, achieved at a power of 200W, resulted in an ILSS retention rate of 67.34% at 300°C and maintained ILSS at 66.46MPa at 350°C. At this power level, the CF surface developed protrusions, increasing its roughness to 155.70 nm and its oxygen content to 18.32%. Additionally, the ratio of polar to nonpolar groups increased to 0.98, and the ID/IG value rose to 2.781. These changes were important reasons for enhancing the high-temperature ILSS of CF/PI composite. [ABSTRACT FROM AUTHOR]

As a dual-functional catalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), Ru clusters have great potential, but there are certain difficulties regarding their stability on the substrate and the tunability of their electronic environment. Here, the S doped graphited biochar aerogel electrocatalyst was designed and synthesized using terrestrial lignin and algal polysaccharide as a carbon substrate. The Ru clusters were anchored on the S-doped carbon aerogel (P-Ru/SC) by carefully designing the Ru-S bond via a novel plasma assisted high temperature carbonization treatment. The optimized P-Ru/SC-2 catalyst exhibits excellent electrocatalytic performance for the HER and OER, achieving ultra-small overpotentials of 119.6 mV and 193.4 mV at 10 mA cm-2. The dual-electrode requires only 1.47 V to reach 10 mA cm-2. It is worth noting that a large number of S sites on graphited carbon can strongly interact with the Ru clusters, significantly improving the catalytic activity and stability for the HER and OER. [ABSTRACT FROM AUTHOR]

ZrB 2 -based composite coatings with addition of Al 2 TiO 5 were prepared via very low-pressure plasma spraying using mechanically mixed powder of ZrB 2 and Al 2 O 3 -40 wt%TiO 2 (AT40). The ablation behavior of the composite coating was investigated using a high temperature plasma jet at a temperature of ∼2500oC. Results demonstrate the addition of AT40 improved the ablation resistance of the ZrB 2 coatings at high temperatures. The coating with 17 vol%AT40 addition exhibited the lowest ablation rate, approximately 1.33 μm/s, which is only one-third of that of the pure ZrB 2 coating. The added AT40 filled the pores between ZrO 2 crystals during ablation, reducing oxygen penetration and lowering the ablation rate. However, excessive addition of AT40 hindered gaseous B 2 O 3 release and thus led to large pore formation, impairing the protective effect. The ZrB 2 -AT40 coating is a promising candidate for high-temperature applications. [ABSTRACT FROM AUTHOR]

The effect of an ionic core on the temperature relaxation in dense hot plasma of beryllium is studied using the pseudpotential model by Gericke et al [Phys. Rev. E 2010, 81, 065401(R)]. Employing the screened version of the ion pseudpotential [by Ramazanov et al, Phys. Plasmas 2021, 28 (9), 092702], we computed the quantum transport cross section for the electron‐ion collisions in dense beryllium plasma, where screening is taking into account using the density response function in the long‐wavelength regime. The results for the transport cross section are used to compute a generalised Coulomb logarithm and electron‐ion collision frequency. Utilizing the latter, we show the effect of the ionic core on the temperature relaxation. To understand the role of the ionic core, we compare the results with the data computed considering ions as point‐like charges. [ABSTRACT FROM AUTHOR]

Radiation hydrodynamical equations with Compton scattering are generally difficult to solve analytically, and usually examined numerically, even if in the subrelativistic regime. We examine the equations available in the subrelativistic regime of k B T |$/$| (m e c 2) ≲ 0.1, h ν |$/$| (m e c 2) ≲ 0.1, and v |$/$| c ≲ 0.1, where T is the electron temperature, ν the photon frequency, and v the fluid bulk velocity. For simplicity, we ignore the induced scattering terms. We then seek and obtain analytical solutions of frequency-dependent radiative moment equations of a hot plasma with bulk motions for several situations in the subrelativistic regime. For example, in the static case of a plane-parallel atmosphere without bulk motions, where equations involve the generalized Kompaneets equation with subrelativistic corrections, we find the Wien-type solution, which reduces to the usual Milne–Eddington solution in the nonrelativistic limit, as well as the power-law-type one, which has a form of [ h ν |$/$| (k B T)]−4. In the moving case of an accelerating one-dimensional flow with bulk motions, we also find the Wien-type and the power-law-type solutions affected by the bulk Compton effect. Particularly, in the Wien-type solutions, due to the bulk Compton effect, the radiation fields gain momentum from the hot plasma in the low-frequency regime of h ν < 3 k B T , while they lose it in the high-frequency regime of h ν > 3 k B T. [ABSTRACT FROM AUTHOR]

Heteroatom doping can efficiently tailor the physicochemical properties of 2D MXene materials for enhancing the energy storage performance. However, in mostly applied doping strategies, the wet chemistry method typically suffers tedious separation and abstersion process while the solid‐phase thermal strategy (traditional furnace heating) employed long‐time （several hours） high‐temperature treatment may cause degradation of MXene. In this work, a universal, energy efficient and environmental‐friendly strategy is reported to realize the heteroatom doping of MXene within seconds by microwave‐induced targeted thermal shock. The MXene film can self‐heat to >800 °C within seconds followed by generating dazzling plasma under microwave field. The high temperature combined with plasma create a localized ultrahigh‐energy environment in MXenes, which promotes the rapid decomposition of preloaded dopant precursors and lattice/surface functional group substitutions between dopant atoms and MXene. The resulted nitrogen (N) and sulfur (S) co‐doped MXene showed significantly improved capacity and performance stability under deformations. Compared with the traditional furnace heating, the targeted heating strategy have significantly higher energy and time efficiencies and reduced carbon footprint. In addition, this method can be readily extended to various element doping of MXene. The microwave‐induced targeted thermal‐shock represents a general and efficient strategy for the fast heteroatom doping of MXene. [ABSTRACT FROM AUTHOR]

The investigation of waves and instabilities in ultra-relativistic charged particle beam–plasma systems is considerable for a wide class of astrophysical environments. Hence, in this study, using relativistic kinetic plasma theory and Lorentz transformations, we study the interaction of a relativistic electron beam with an ultra-relativistic hot plasma. First, we obtain the dispersion relation of fast and slow longitudinal waves and consequently the growth rate of the slow wave (negative-energy wave) instability. Then, we plot the instability growth rate in terms of different physical parameters, such as the Lorentz factor, the electron beam density, the thermal velocity of electrons, and the temperature of the beam particles, and discuss them further. Our results in the ultra-relativistic regime show that the growth rate of instability decreases by increasing the Lorentz factor and thermal velocity of particles, while the beam density enhances the growth rate of instability. Moreover, a comparison with the results obtained from previous studies shows that the growth rate of instability in the cold electron beam–cold plasma interaction is higher than the instability growth rate in the case of the relativistic electron beam and ultra-relativistic hot plasma. [ABSTRACT FROM AUTHOR]

ZrC dispersion-strengthened W exhibits high strength/ductility, low ductile-to-brittle transition temperature, and excellent thermal shock resistance, making it a promising candidate plasma-facing material for future fusion devices. In this study, surface modification of 0.5 wt.% ZrC dispersion-strengthened W (WZrC) under low energy and high fluence He plasma irradiation at high temperature was presented. Under the energy of 90 eV and fluence ranging from 6 × 1024 He·m−2–2 × 1026 He·m−2 He irradiation at 920 °C, a typical fuzz nanostructure appeared on the W matrix of WZrC. The thickness of fuzz layer is proportional to the square root of He irradiation fluence. The fuzz showed comparable thickness and structural features to pure W, indicating limited effects of the particle's addition on resistance to high fluence He irradiation at high temperatures. Under continuous He injection, the fuzz would grow extending onto the particle area, making the particle obscured. Besides, the erosion behavior of particles under He plasma irradiation has been investigated, which is thought to be dominated by a sputtering process. Under the He influence of 6 × 1024 He·m−2, only nanopores were observed in the surface region. With fluence increasing to 5 × 1025 He·m−2, the surface became relatively uneven with larger holes. W aggregated in spots and distributed on the surface of the particle, which might be the result of subthreshold sputtering and deposition. When fluence further increased to 2 × 1026 He·m−2, the particles were eroded completely and covered by the extended fuzz, forming cavities. In addition, distinctive layered nanotendrils were observed above the cavities, which were characterized to consist of inner W-riched skeletons and outer Zr-riched layers. It indicates that the layered nanotendrils should be the result of fuzz extension combined with particle sputtering/deposition. [ABSTRACT FROM AUTHOR]

The old nova and intermediate polar (IP) GK Persei underwent one of its recurrent dwarf nova (DN) outbursts in 2018. We proposed monitoring it in UV and X-rays with the Neil Gehrels Swift Observatory, starting less than six days after the eruption, until 16 days after the eruption ended. For the first time, we could follow the decay to the minimum light UV and X-rays. We present the timing and spectral analysis, comparing the results with the previous outbursts and with the quiescent status. We confirm the spin modulation in X-rays with a period P WD = 351.325(9) s, only in the 2–10 keV range. The period was not detected in the 0.3–2 keV range and in the UV band, suggesting that the soft portion of the X-ray spectrum in GK Per does not originate near the poles, but in a wind or circumstellar material. The amplitude of the modulation was less prominent than in 2015, a fact that seems correlated with a lower average mass accretion rate. The spectral fits are consistent with a mass accretion rate increasing by a factor of 2 from rise to maximum and decreasing during the return to minimum, following the trend of the modulation amplitude. The maximum plasma temperature is higher than the Swift XRT energy range of 0.3–10 keV, thus it is not well constrained, but our spectral fits indicate that it may have varied irregularly during the outburst. [ABSTRACT FROM AUTHOR]

Simulation of full wave, without paraxial approximation, high-resolution solution of wave equations in frequency domain in the electron cyclotron resonance (ECR) frequency range for realistic Tokamak plasma parameters became possible by using recently formulated hybrid iterative algorithm [Svidzinski et al., Phys. Plasmas 25, 082509 (2018)] for numerically solving discretized wave equations. This approach combines time evolution and iterative relaxation techniques into iteration cycles. This algorithm is implemented in 2D code FullWave, solving wave equations in Tokamaks in cold and hot plasma models, and it has been tested in 3D full wave iterative RF beams simulation tool, which is presently being developed to model 3D ECRH RF beams in fusion devices using dynamic grid adaptation. The results of 2D full wave modeling, assuming specified toroidal mode number, of ECRH RF beams in DIII-D plasma, performed in the cold and hot plasma models for outboard and top launch scenarios using FullWave are presented. Nonlocal hot plasma response model, based on accurate numerical solution of linearized Vlasov equation, is used to model beam propagation and absorption in the 2nd electron cyclotron harmonic region. Demonstration of capability of the hybrid iterative algorithm to model ECRH RF beams in 3D is made by simulating a substantial part of realistic beam in DIII-D, launched from outboard side of the machine. All relevant physics of RF beam propagation, most of which is not captured in paraxial approximation, such as beam's divergence, interference between the X and O modes in the beam, X-O mode conversion, beam splitting into the X and O mode beams, transformation of beam's cross section, and absorption at the 2nd electron cyclotron harmonic, is captured in the simulations. A numerical technique to find an optimal beam polarization at the launcher to launch a nearly pure X or O mode beam in plasma is developed and tested. [ABSTRACT FROM AUTHOR]

We report striking Doppler velocity gradients observed during the well-observed 2017 September 10 solar flare, and argue that they are consistent with the presence of an above-the-looptop termination shock beneath the flare current sheet. Observations from the Hinode Extreme-ultraviolet Imaging Spectrometer measure plasma sheet Doppler shifts up to 35 km s−1 during the late-phase of the event. By comparing these line-of-sight flows with plane-of-sky (POS) measurements, we calculate total velocity downflows of 200+ km s−1, orientated ≈6–10° out of the POS. The observed velocities drop rapidly at the base of the hot plasma sheet seen in extreme ultraviolet, consistent with simulated velocity profiles predicted by our 2.5D magnetohydrodynamics model that features a termination shock at the same location. Finally, the striking velocity deceleration aligns spatially with the suppression of Fe  xxiv non-thermal velocities, and a 35–50 keV hard X-ray looptop source observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager. Together, these observations are consistent with the presence of a possible termination shock within the X8.2-class solar flare. [ABSTRACT FROM AUTHOR]

Kr L-shell spectroscopy modeling results are discussed in this paper, focusing on the n = 4 to n = 2 line transitions of Be- and Li-like Kr ions. Collisional radiative atomic kinetic and Stark-broadened spectral line shape calculations show electron temperature T e and density n e sensitivity in the spectrum. The combination of the T e dependence due to the relative intensity of Be-like to Li-like line emissions in the range from 1.5 to 3 keV and the n e sensitivity from the Stark broadening effect on the line shapes in the range from 5 × 10 23 to 2 × 10 24 / cc results in a spectrum that can be employed to diagnose T e and n e . Two different collisional radiative atomic kinetic models i.e., Prismspect [J. J. MacFarlane, et al., Int. Fusion Sci. Appl. Conf. Proc. 457 (2003)] and ABAKO [Florido, et al., PRE, 80, 056402 (2009)] produce similar results in level populations and spectra. In x-ray spectroscopy of implosion cores, this Kr L-shell spectrum may prove useful in an intermediate T e range in which Ar is too ionized for its K-shell to be of diagnostic value and Kr is not ionized enough for its K-shell emission to be useful. [ABSTRACT FROM AUTHOR]

The study of self-lubricating coatings is a rapidly developing research field that is expected to address major issues arising from operation under high loads and thermal stresses of machine parts. It is of utmost importance that various critical tribological pairs such as crankshaft bearings, piston rings maintain their integrity, thus contributing to the engines efficient and reliable operation for long periods of time. Therefore, a choice of high-strength metals is required, with special treatments and/or coatings in combination with sufficient lubrication. In the present study, liquid lubricants encapsulated in poly(urea-formaldehyde) shells were incorporated in ceramic-metal matrices to produce composite coatings by Atmospheric Plasma Spraying. Aspects concerning the survival of the capsules during their flight through the high temperature plasma flame, the maintenance of their integrity at impact with the substrate with high kinetic energy, their homogeneous dispersion within the coating mass, thermal spray deposition parameters adjustment and optimization are thoroughly discussed. Coating properties such as roughness, friction, adhesion strength, and wear behaviour were also investigated. Microstructural characteristics and friction-wear behaviour were found to be critical to the durability of coating. [ABSTRACT FROM AUTHOR]

Unstable states of different charged species in the solar wind and Earth's magnetosphere are governed with the collective and collisional processes. For these dilute plasmas, the contribution of microinstabilities driven by the anisotropic particle distribution and heat flux becomes important in defining the stable/equilibrium states of electrons and ions/protons. The present paper highlights the key role of proton firehose instability to regulate an unchecked rise in the temperature anisotropy in these solar wind and magnetospheric environments. Right-handed circularly polarized proton firehose mode becomes unstable when the temperature condition of T‖p > T⊥p is satisfied, where the directional subscripts denote directions with respect to the ambient magnetic field. Based on the observations of magnetospheric multi-scale (MMS) space mission, we assume the bi-Maxwellian nature of the model distribution for the multi-component proton plasma. To study the time evolution of the unstable mode, we further allow the time variation in the cold and hot proton temperatures. For the choice of the initial conditions related with observations, we unveil the wave properties (growth and unstable wave number domain) corresponding to the cold/hot proton temperature anisotropy and the plasma betas of constituents proton components. In the back action of proton firehose instability, we highlight the time-scale modifications and saturation of initial bi-Maxwellian distributions and resulting wave-energy densities for various choices of initial cold-hot temperature anisotropy and plasma betas. [ABSTRACT FROM AUTHOR]

This paper is based on a report at the 2nd International Fusion Plasma Conference & 13th International Conference on Open Magnetic Systems for Plasma Confinement (iFPC & OS 2023), August 21–25, 2023, Busan, Korea and provides a brief overview of the status of work at the Budker Institute on the study of hot plasma confinement in open-type magnetic traps with a linear axisymmetric configuration. The main attention is paid to key problems: magnetohydrodynamics (MHD) stability in regimes with extremely high relative pressure, longitudinal electronic thermal conductivity, stability with respect to the development of kinetic modes and transverse transport. This paper provides an overview of the methods we are developing to address these problems, the experimental and theoretical results achieved and plans for future development. The last section of the article provides brief information about the preliminary design of the gas-dynamic multiple-mirror trap device, the development of which has been completed. [ABSTRACT FROM AUTHOR]

We present the results of numerical simulation by two-dimensional hybrid particle-in-cell code of high-beta plasma with hot ions in an axisymmetric mirror machine. Two particular effects are discussed: the self-rotating of plasma with Maxwellian ions in regime of diamagnetic confinement and the excitation of axisymmetric magnetosonic waves in a high-beta plasma with sloshing ions. [ABSTRACT FROM AUTHOR]

At present, the research on cathode plasma electrolytic deposition (CPED) mainly focuses on improving the coating properties, while the initial structure and formation mechanism of CPED coating are less studied. This work aims to study the initial deposition behavior of Al 2 O 3 coating by CPED at different time scales systematically. The results show that the coating consists of lamellar Al(OH) 3 in the pre-plasma discharge period. After reaching the breakdown potential, the preparation process of Al 2 O 3 can be considered as a cyclic process: plasma discharge, injection of molten oxide, sintering and solidification, and stacking. Such an iterative process results in a gradual thickening of the coating. Later in the deposition process, the raised structure of the coating surface flaps off and coating thickness decreases. In addition, the high temperature during plasma discharge results in local melting of the substrate surface, which is co-deposited with Al 2 O 3. [ABSTRACT FROM AUTHOR]

Comparison between the analytic theory of n = 0 vertical displacement modes in magnetically confined plasmas of fusion interest and numerical simulations using the extended-MHD code NIMROD is presented. Agreement between analytic and numerical results is highly satisfactory. Differences are interpreted to be caused mostly by the different wall shape and by the presence of a halo plasma surrounding the hot plasma adopted in NIMROD. A numerical study of vertical displacement oscillatory modes [Barberis et al., J. Plasma Phys. 88, 905880511 (2022)] is presented. Axisymmetric X-point currents supported by the halo plasma are discussed. The article provides a successful benchmark and a useful starting point for future numerical investigations of n = 0 modes using more realistic tokamak geometry and plasma equilibria. [ABSTRACT FROM AUTHOR]

Context. The bright heads of penumbral filaments, penumbral grains (PGs), show apparent horizontal motions inward, toward the umbra, or outward, away from the umbra. Aims. We aim to ascertain statistically whether the direction of PGs' apparent motion is related to the inclination of the surrounding magnetic field. Methods. We used spectropolarimetric observations of five sunspot penumbrae to compare magnetic inclinations inside PGs with those in their surroundings. The data were taken by three observatories: the Hinode satellite, the Swedish Solar Telescope, and the GREGOR solar telescope. The direction of PGs' motion was determined by feature tracking. The atmospheric conditions in PGs and their surroundings, including magnetic field information, were retrieved by means of height-stratified spectropolarimetric inversions. Results. Out of a sample of 444 inward-moving PGs and 269 outward-moving ones, we show that 43% of the inward-moving PGs have a magnetic inclination larger by 8° ±4° than the inclination in their surroundings and 51% of the outward-moving PGs have an inclination smaller by 13° ±7° than the surrounding one. The opposite relation of inclinations is observed in only one fifth of the inward- and outward-moving PGs. Conclusions. Rising hot plasma in PGs surrounded by a less inclined magnetic field may adapt its trajectory to be more vertical, causing an inward apparent motion of PGs. Conversely, it may be dragged by a more horizontal surrounding magnetic field such that an outward apparent motion is observed. [ABSTRACT FROM AUTHOR]

Context. During the first four all-sky surveys eRASS:4, which was carried out from December 2019 to 2021, the extended Roentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Roentgen-Gamma (Spektr-RG, SRG) observed the Galactic H II region, the Carina nebula. Aims. We analysed the eRASS:4 data to study the distribution and spectral properties of the hot interstellar plasma and the bright stellar sources in the Carina nebula. Methods. The spectral extraction regions of the diffuse emission were defined based on the X-ray spectral morphology and multi-wavelength data. The spectra were fit with a combination of thermal and non-thermal emission models. The X-ray bright point sources in the Carina nebula are the colliding wind binary η Car, several O stars, and Wolf–Rayet (WR) stars. We extracted the spectra of the brightest stellar sources, which can be well fit with a multi-component thermal plasma model. Results. The spectra of the diffuse emission in the brighter parts of the Carina nebula are well reproduced by two thermal models, a lower-temperature component (~0.2 keV) and a higher-temperature component (0.6–0.8 keV). An additional non-thermal component dominates the emission above ~1 keV in the Central region around η Car and the other massive stars. Significant orbital variation in the X-ray flux was measured for η Car, WR 22, and WR 25. η Car requires an additional time-variable thermal component in the spectral model, which is associated with the wind-wind collision zone. Conclusions. Properties such as temperature, pressure, and luminosity of the X-ray emitting plasma in the Carina nebula derived from the eROSITA data are consistent with theoretical calculations of emission from superbubbles. This confirms that the X-ray emission is caused by the hot plasma inside the Carina nebula that has been shocked-heated by the stellar winds of the massive stars, in particular, of η Car. [ABSTRACT FROM AUTHOR]

In the previous paper Liu and Pu (2019) [17] , we proved the nonlinear Schrödinger (NLS) approximation for the Euler-Poisson system for a hot ion-acoustic plasma, where the appearance of resonances and the loss of derivatives of quadratic terms are the main difficulties. Note that when the ion-acoustic plasma is hot, the Euler-Poisson system is Friedrich symmetrizable, and the linear term can provide a derivative to compensate the loss of derivative induced by quadratic terms after diagonalizing the linearized system. When the ion-acoustic plasma is cold, as considered in the present paper, the situation is very different from that in the previous paper. The Euler-Poisson system becomes a pressureless system, so the linear operator has no regularity, and the quadratic terms still lose a derivative in the diagonalized system. This fact makes it more difficult to prove the NLS approximation of Euler-Poisson system for a cold ion-acoustic plasma. In this paper, we take advantage of the special structure of the pressureless Euler-Poisson system and the normal-form transformation to deal with the difficulties caused by resonances, especially the difficulties caused by derivative loss, in order to prove the NLS approximation. [ABSTRACT FROM AUTHOR]

The extremely harsh environment of the high temperature plasma imposes strict requirements on the construction materials of the first wall in a fusion reactor. In this work, a refractory alloy system, WTaVTiZrx, with low activation and high entropy, was theoretically designed based on semi-empirical formula and produced using a laser cladding method. The effects of Zr proportions on the metallographic microstructure, phase composition, and alloy chemistry of a high-entropy alloy cladding layer were investigated using a metallographic microscope, XRD (X-ray diffraction), SEM (scanning electron microscope), and EDS (energy dispersive spectrometer), respectively. The high-entropy alloys have a single-phase BCC structure, and the cladding layers exhibit a typical dendritic microstructure feature. The evolution of microstructure and mechanical properties of the high-entropy alloys, with respect to annealing temperature, was studied to reveal the performance stability of the alloy at a high temperature. The microstructure of the annealed samples at 900 °C for 5–10 h did not show significant changes compared to the as-cast samples, and the microhardness increased to 988.52 HV, which was higher than that of the as-cast samples (725.08 HV). When annealed at 1100 °C for 5 h, the microstructure remained unchanged, and the microhardness increased. However, after annealing for 10 h, black substances appeared in the microstructure, and the microhardness decreased, but it was still higher than the matrix. When annealed at 1200 °C for 5–10 h, the microhardness did not increase significantly compared to the as-cast samples, and after annealing for 10 h, the microhardness was even lower than that of the as-cast samples. The phase of the high entropy alloy did not change significantly after high-temperature annealing, indicating good phase stability at high temperatures. After annealing for 10 h, the microhardness was lower than that of the as-cast samples. The phase of the high entropy alloy remained unchanged after high-temperature annealing, demonstrating good phase stability at high temperatures. [ABSTRACT FROM AUTHOR]

It is shown that the radial profile of the electron temperature in the Globus-M2 spherical tokamak is related to the radial profile of the electron density by a power law . An analytical model of the density attractor, assuming the dependence of on the specific poloidal volume v, previously tested on the TCV and JET tokamaks with a large aspect ratio, holds on the spherical tokamak, and the approximation of 162 experimental profiles has resulted in . The proposed model makes it possible to calculate the spatial distribution and according to a known magnetic configuration. [ABSTRACT FROM AUTHOR]

Plasma, the fourth fundamental state of matter, comprises charged species and electrons, and it is a fascinating medium that is spread over the entire visible universe. In addition to that, plasma can be generated artificially under appropriate laboratory techniques. Artificially generated thermal or hot plasma has applications in heavy and electronic industries; however, the non-thermal (cold atmospheric or low temperature) plasma finds its applications mainly in biomedicals and therapeutics. One of the important characteristics of LTP is that the constituent particles in the plasma stream can often maintain an overall temperature of nearly room temperature, even though the thermal parameters of the free electrons go up to 1 to 10 keV. The presence of reactive chemical species at ambient temperature and atmospheric pressure makes LTP a bio-tolerant tool in biomedical applications with many advantages over conventional techniques. This review presents some of the important biomedical applications of cold-atmospheric plasma (CAP) or low-temperature plasma (LTP) in modern medicine, showcasing its effect in antimicrobial therapy, cancer treatment, drug/gene delivery, tissue engineering, implant modifications, interaction with biomolecules, etc., and overviews some present challenges in the field of plasma medicine. [ABSTRACT FROM AUTHOR]

The paper presents an investigation of the plasma fluctuation in the SMOLA helical mirror, which is suspected to be responsible for anomalous scattering. The helical mirror confinement is effective when the ion mean free path is equal to the helix pitch length. This condition can be satisfied in hot collisionless plasma only by anomalous scattering. The wave, which scatters the passing ions, is considered to receive energy from the trapped ions. The oscillations of the electric field in the helically symmetric plasma were observed in experiment. The oscillations have both regular highly correlated and chaotic components. The dependency of the regular component frequency on the Alfvén velocity is linear for $V_{\rm A} and constant for higher values. It is shown experimentally that the condition for the wave to be in phase resonance with the trapped ions is satisfied in a specific region of the plasma column for the highly correlated component. The amplitude of the chaotic component (up to $3\ \text {V}\ \text {cm}^{-1}$) is higher than the estimated electric field required for the ion scattering. [ABSTRACT FROM AUTHOR]

We successfully offer a quantitative and qualitative analysis of the micro-toxic elements that are found in various brands of commercial ink powders (CIPs) available in Saudi Arabia employing short-long orthogonal double-pulse laser-induced plasma spectroscopy (SLODP-LIPS), and an inductively coupled plasma-optical emission spectrometer (ICP-OES). The compositional analysis exploiting the fast detection SLODP-LIPS geometry is based on the received emission spectra of the laser-generated ink plasma flare to promote the SNR (signal-to-noise ratio) compared to the single-pulse (SP) LIPS geometry. The investigated elemental composition of CIPs brands was compared with ICP-OES. The emission optical spectra of the CIPs contain spectral lines of aluminium, antimony, cadmium, calcium, carbon, chromium, copper, lead, iron, potassium, silicon, sodium, and zinc, with varying intensities. To overwhelm the struggle of inadequate SP-LIPS sensitivity or calibration-free LIPS (CF-LIPS) routine characterisation of the tested material and to accomplish a greater emitting volume, grander atomised mass, the lower detection limit, and higher plasma temperature, a double-pulse alternate for sample vaporisation were exercised in our work. The density and electron temperature of the spectral lines of the pertinent elements were deduced by stark-broadening and Boltzmann plot, with an average of about 1.23 × 1018 cm−3 and 9300 ± 200 K, respectively. It was found that both outcomes from SLODP-LIPS and ICP-OES were in greater agreement. The analysis of different commercial ink brands shows that SLODP-LIPS is a potent scheme for the analysis of the micro-toxic trace element in any solids. [ABSTRACT FROM AUTHOR]

In high confinement mode (H-mode) in the tokamak Globus-M2, the development of edge-localized modes (ELMs) is accompanied by the appearance of filament structures. Using the Doppler backscattering method allowed to determine the parameters of the filaments during ELMs triggered by and independent from saw-tooth crashes. It was shown that the number of filaments observed during ELMs synchronized with saw-tooth crashes is greater and the area of their observation is wider. The filament velocity during all observed ELM types on Globus-M2 is higher than was the case on the Globus-M tokamak. Filaments that developed immediately before an ELM burst are characterized by smaller amplitudes and velocities. Two diagnostics, Doppler backscattering and poloidal correlation Doppler reflectometry, were used to determine the poloidal velocity of such filaments and the results demonstrated that the velocity values obtained had similar values, which may indicate linear backscattering taking place off these filaments. [ABSTRACT FROM AUTHOR]

Based on the results of measurements near the equatorial plane a fluxes and energy spectra of H+ and O+ ions of the magnetosphere's ring current by the OGO-3, Explorer 45, AMPTE/CCE, and Van Allen Probes (A and B) satellites, a systematic analysis of spatial distributions of the energy density for these ions on the main phase of magnetic storms was carried out. Twelve storms of different strength were considered, with max|Dst| from 64 to 307 nT. The radial profile of the ring current ions energy density is characterized by the maximum (Lm) and by the ratio of the energy densities of the ions and the magnetic field at this maximum (βm), and at L > Lm this profile is approximated by the function w(L) = w0 exp(–L/L0). Quantitative dependences of the parameter Lm on the Dst index and MLT, and also the dependences of the parameters βm, w0 and L0 on the Dst, MLT and Lm, are obtained. These dependences are different for H+ and O+ ions, as well as for ions of low (E < 60 keV) and higher energies. It has been established that in a narrow inner region of the ring current near its maximum in the nighttime hemisphere of the magnetosphere, the RC asymmetry is much smaller (especially for O+ ions) than at L > Lm. It was found that with increasing L, the asymmetry of the ring current by MLT increases significantly, with H+ ions concentrated at near 18 MLT, and O+ ions at near 24 MLT. It is shown that for O+ ions with E ∼ 1–300 keV, βm ∝ ; this result shows that a deeper penetration of hot plasma into a geomagnetic trap, during strong storms, requires not only a stronger electric field of convection, but also a significant preliminary accumulation and acceleration of ions (especially O+ ions) in the sources of the ring current. [ABSTRACT FROM AUTHOR]

The effect of powder characteristics on the sintering behaviour and microstructure of densified W by spark plasma sintering and post-hot isostatic pressing was investigated. W powder was prepared by ultrasonic spray pyrolysis of a W precursor and hydrogen reduction, and a commercially available powder was used for comparison. The synthesised W powders were present in the form of large agglomerates composed of nano-sized particles. The densified specimens prepared by ultrasonic spray pyrolysis showed lower relative density and larger grain size than when commercial powder was sintered under the same conditions. Microstructural observation for the specimen sintered using the powder of ultrasonic spray pyrolysis revealed that the relatively large pores are present along the grain boundaries. The observed microstructural features were discussed by sintering behaviour based on the effect of intra-agglomerate and inter-agglomerate pores in the initial powder on densification and grain growth. [ABSTRACT FROM AUTHOR]

We explore the electromagnetic wave modes that can exist in a cosmological plasma dominated by dark energy due to a cosmological constant. It is found that, in the cold and hot plasma cases, electromagnetic plasma wave modes can be found exactly. The effect of this cosmology appears as a time-dependent potential in the wave equation for the electromagnetic modes, which effectively modifies the frequency response of the plasma. This potential depends on the metric of the spacetime and on the thermodynamical properties of the plasma. For both cases, cold and hot, the solutions are found in terms of Airy and Bessel functions, respectively. When those solutions are required to have vanishing initial conditions, a discretization on the wavelengths of the electromagnetic plasma waves is imposed. Thus, only some specific wave modes can exist in this dark energy cosmology. Relaxing those conditions, we obtain other solutions that approximate to plane waves only in the very hot plasma limit. [ABSTRACT FROM AUTHOR]

Using computer simulation, the sputtering coefficients of a beryllium target upon bombardment with hydrogen isotopes in the particle energy range 8 eV–100 keV and the dependences of the sputtering coefficients on the angle of incidence of the beam are obtained. Obtained results allow to estimate the sputtering of the ITER first wall and the entry of beryllium impurities into the hot plasma zone. Formulas are proposed for estimating the energy sputtering threshold and describing the sputtering coefficient dependence on the angle of incidence of the beam. [ABSTRACT FROM AUTHOR]

De-excitation gamma-ray lines, produced by nuclei colliding with protons, provide information about astrophysical environments where particles have kinetic energies of 10–100 MeV per nucleon. In general, such environments can be categorized into two types: the interaction between non-thermal MeV cosmic rays and ambient gas, and the other is thermal plasma with a temperature above a few MeV. In this paper, we focus on the latter type and investigate the production of de-excitation gamma-ray lines in very hot thermal plasma, especially the dependence of the line profile on the plasma temperature. We have calculated the line profile of prompt gamma rays from 12C and 16O and found that when nuclei have a higher temperature than protons, gamma-ray line profiles can have a complex shape unique to each nucleus species. This is caused by anisotropic gamma-ray emission in the nucleus rest frame. We propose that the spectroscopy of nuclear de-excitation gamma-ray lines may enable to probe energy distribution in very hot astrophysical plasmas. This diagnostics can be a new and powerful technique to investigate the physical state of a two-temperature accretion flows onto a black hole, especially the energy distributions of the protons and nuclei, which are difficult to access for any other diagnostics. [ABSTRACT FROM AUTHOR]

The role of energetic outflows from galactic nuclei in shaping galaxy formation and evolution is still shrouded in uncertainty. In this study, we shed light on this complex phenomenon by presenting evidence for a large-scale bipolar radio/X-ray-emitting bubble-like structure emanating from the central region of the nearby disc galaxy M106 (NGC 4258). Our findings, based on Low-Frequency Array survey data and Chandra observations, provide a glimpse into the underlying physical processes driving this enigmatic structure. Similar to the eROSITA / Fermi bubbles in our own Galaxy, the M106 bubbles enclose diffuse hot plasma and are partially bounded by prominent radio/X-ray-emitting edges. We constrain the magnetic field and cosmic-ray properties of the structure. The analysis of the X-ray data gives an estimate of the thermal energy of the bubbles as ∼8 × 1056 erg. This energy can be supplied by the jets and perhaps by the wind from the accretion flow of the galaxy's low-luminosity AGN, which most likely has been much more powerful in the recent past, with an average mechanical energy release rate of ∼4 × 1042 erg s−1 over the last ∼8 × 106 yr – the estimated age of the structure. We also show evidence for diffuse X-ray emission on larger scales, indicating the presence of a hot galactic corona. Our results provide a clear manifestation of galactic nuclear feedback regulating the gas content and energetics of the circumgalactic medium of disc galaxies similar to our own. [ABSTRACT FROM AUTHOR]

Low-collisionality plasma in a magnetic field generically develops anisotropy in its distribution function with respect to the magnetic field direction. Motivated by the application to radiation from accretion flows and jets, we explore the effect of temperature anisotropy on synchrotron emission. We derive analytically and provide numerical fits for the polarized synchrotron emission and absorption coefficients for a relativistic bi-Maxwellian plasma (we do not consider Faraday conversion/rotation). Temperature anisotropy can significantly change how the synchrotron emission and absorption coefficients depend on observing angle with respect to the magnetic field. The emitted linear polarization fraction does not depend strongly on anisotropy, while the emitted circular polarization does. We apply our results to black hole imaging of Sgr A* and M87* by ray tracing a GRMHD simulation and assuming that the plasma temperature anisotropy is set by the thresholds of kinetic-scale anisotropy-driven instabilities. We find that the azimuthal asymmetry of the 230 GHz images can change by up to a factor of 3, accentuating (T ⊥ > T ∥) or counteracting (T ⊥ < T ∥) the image asymmetry produced by Doppler beaming. This can change the physical inferences from observations relative to models with an isotropic distribution function, e.g., by allowing for larger inclination between the line of sight and spin direction in Sgr A*. The observed image diameter and the size of the black hole shadow can also vary significantly due to plasma temperature anisotropy. We describe how the anisotropy of the plasma can affect future multifrequency and photon ring observations. We also calculate kinetic anisotropy-driven instabilities (mirror, whistler, and firehose) for relativistically hot plasmas. [ABSTRACT FROM AUTHOR]

In this paper, we performed a spectro-polarimetric analysis of the transient NS-LMXB XTE J1701−462 using IXPE, NICER , and NuSTAR data during its 2022 outburst. We report significant detection of energy-dependent polarization in the X-ray signal from the source on 2022 September 29 in the 2–4, 4–8, and 2–8 keV energy bands with a polarization degree of 3.9 ± 0.3, 5.5 ± 0.6, and 4.5 ± 0.4 per cent, respectively. The polarization angle in the overall 2–8 keV band was ∼143° ± 2°. The spectra were modelled using a combination of thermal emission from an accretion disc, Comptonized emission from a hot electron plasma (or corona) and a Gaussian line. From spectro-polarimetric analysis, the polarization degree due to the disc emission had an upper limit of ∼11.5 per cent, and that of the Comptonized emission was constrained at 7.7 ± 2.5 per cent (at the 3σ level). The results suggest that the Comptonized component probably originates from a spreading-layer/boundary-layer above the neutron star surface. IXPE observation of the source on 2022 October 8 does not show significant polarization which can be attributed to a weakening of the coronal Comptonized emission. The implication of these results are discussed. [ABSTRACT FROM AUTHOR]

The goal of this paper is to assess the possibility of using a new three-ion ICRF heating scheme on the spherical tokamak Globus-M2. In the first place, the operating frequencies and positions of cyclotron harmonics were found. Matching with frequency band of RF system of Globus-M2 was made. The absorption of electromagnetic waves was modeled using a one-dimensional full-wave code. Since the appearance of high-energy particles is expected in the three-ion ICRF scheme of heating special attention is paid to a comparing the estimates for generated particles energies with their confinement in tokamak Globus-M2. [ABSTRACT FROM AUTHOR]

The relaxed state of a magnetized relativistic hot plasma composed of inertial electrons and positrons having different relativistic temperatures and a fraction of static positive ions is studied. From the steady-state solutions of vortex dynamics equations and the relation for current density, a non-force-free triple Beltrami (TB) relaxed state equation is derived. The TB state is characterized by three scale parameters that consequently provide three different self-organized structures. The analysis of the relaxed state shows that for specific values of generalized helicities, the disparity in relativistic temperature and the existence of a small fraction of static positive ions in pair plasma can transform the nature of scale parameters. Moreover, an analytical solution of the TB state for an axisymmetric cylindrical geometry with an internal conductor configuration demonstrates that due to asymmetries of temperature and density of plasma species, diamagnetic structures can transform into paramagnetic ones and vice versa. The present study will improve our understanding of pair plasmas in trap-based plasma confinement experiments and astrophysical environments. [ABSTRACT FROM AUTHOR]

Results of experiments carried out with a quasi-stationary L-2M stellarator in the regime of electron cyclotron resonance heating by means of two gyrotrons are presented. The data on increase in the plasma energy lifetime by means of modulation (profiling) of the microwave pulse are obtained. The first gyrotron operating at fixed power was used for ionization and initial heating of plasma, while the second gyrotron initiated a stationary discharge with a duration of 10 ms. It is demonstrated that the lifetime can be increased by varying the second-gyrotron power in the range of 50–200 kW. A fourfold increase in the lifetime was obtained when the second-gyrotron power was reduced to 50 kW. This work is of interest as a method of studying hot plasma confined in the toroidal magnetic system of a stellarator. [ABSTRACT FROM AUTHOR]

We examine the impact of the hot drifting electron on stimulated Raman backscattering, which is coupled to decay instability, in a magnetized plasma. Through parametric coupling, this produces a plasma wave that moves forward and an electromagnetic wave that shifts downward. The plasma wave produced by stimulated Raman scattering (SRS) in this process decays into an ion-acoustic wave and a secondary, longer-wavelength Langmuir wave traveling opposite to the ion-acoustic wave. This energy diversion and attenuation of the primary Langmuir wave by drifting electrons limit the amplitude of SRS. In the presence of drifting electrons, the SRS is suppressed significantly and the plasma wave is attenuated resonantly at a higher rate. [ABSTRACT FROM AUTHOR]

Thermodynamic properties and equations of state of the electron–positron plasma (or gas) at high and very high temperatures (T ≥ 170 keV) are derived and investigated. We have derived a number of simple analytical formulas for the Fermi–Dirac distribution functions, which can be applied to various Fermi gases and plasmas in different cases. Almost all these formulas are represented in the form of series expansions. The coefficients in these expansions are relatively simple functions of the μ T ratio, where T is the temperature and μ is the chemical potential of this Fermi system. Our approach works well for high-temperature electron–positron plasmas, which are in thermal equilibrium with the photon gas of annihilation γ - quanta, and for the model gas of fermions, where there is no radiation at all. The first case corresponds to the ultra-relativistic limit for high-temperature electron–positron plasma, while the second case represents a model Fermi gas of particles, which has some non-zero chemical potential. By investigating sources of annihilation γ - quanta in our Galaxy, we have arrived to a remarkable conclusion about the high-temperature limit in our regular (photon) optics. [ABSTRACT FROM AUTHOR]

The Pillars of Creation, one of the most recognized objects in the sky, are believed to be associated with the formation of young stars. However, so far, the formation and maintenance mechanism of the pillars are still not fully understood due to the complexity of the nonlinear radiation magnetohydrodynamics (RMHD). Here, assuming laboratory laser-driven conditions, we studied the self-consistent dynamics of pillar structures in magnetic fields by means of two-dimensional and three-dimensional (3D) RMHD simulations, and the results support our proposed experimental scheme. We find that only when the magnetic pressure and ablation pressure are comparable, the magnetic field can significantly alter the plasma hydrodynamics. For medium-magnetized cases (β initial ≈ 3.5), the initial magnetic fields undergo compression and amplification. This amplification results in the magnetic pressure inside the pillar becoming large enough to support the sides of the pillar against radial collapse due to pressure from the surrounding hot plasma. This effect is particularly pronounced for the parallel component (B y ), which is consistent with observational results. In contrast, a strong perpendicular (B x , B z ) magnetic field (β initial < 1) almost retains its initial distribution and significantly suppresses the expansion of blown-off gas plasma, leading to the inability to form pillar-like structures. The 3D simulations suggest that the bending at the head of "Column I" in the Pillars of Creation may be due to nonparallel magnetic fields. After similarity scaling transformation, our results can be applied to explain the formation and maintenance mechanism of the pillars, and can also provide useful information for future experimental designs. [ABSTRACT FROM AUTHOR]

Based on observations at the RT-7.5 radio telescope of the Bauman Moscow State Technical University at a wavelength of 3.2 mm (93 GHz), along with other ground-based and space instruments (Siberian Radioheliograph, Solar Dynamics Observatory (SDO), Metsähovi Radio Observatory), the origin of millimeter radiation from X-ray class M 5.7 SOL2022-05-04T08:45 solar flare was investigated. An analysis of the time profiles of radiation in the X-ray and radio ranges showed that the millimeter emission source is not associated with hot (5 × 105–107 K) coronal plasma. This is also evidenced by the estimate of the sub-THz flux from radiating hot plasma according to the AIA/SDO data, which turned out to be much less than the observed values. Indications of the development of thermal instability in flare ultraviolet loops were obtained. The relationship between the millimeter emission of the flare and the heat source in the solar chromosphere has been substantiated. [ABSTRACT FROM AUTHOR]

We consider axisymmetric equilibrium of a tokamak plasma that includes current carried by relativistic runaway electrons (REs). Using a guiding center approach, a qualitative picture of the equilibrium of a pure RE beam is elucidated. In a hot thermal plasma, none of the classical drifts of charged particles contribute to the net field-perpendicular current density, which is purely due to magnetization current. In the case of a runaway beam, however, the curvature drift of REs provides the Lorentz force needed to maintain the centripetal acceleration associated with the relativistic toroidal motion. Two different equilibrium formulations are derived for the general case consisting of a mix of thermal and RE current. At higher RE energies, the shift between flux-surfaces and surfaces of constant generalized angular momentum of REs in such equilibria can exceed the radial extent of a typical magnetohydrodynamic mode such that its stability properties could be altered. Simplified one-dimensional governing equations are derived for the absolute and relative orbit shifts in the case of a circular tokamak, enabling quick estimates of parameter dependencies. [ABSTRACT FROM AUTHOR]

The influence of the mixing of Au with D and T (DT) upon alpha heating is studied in the wide ranges of plasma temperatures from 0.1 to 100.0 keV, under the assumption that all the charged particles in the mixture are in the same temperature. Two cases of mixture densities 4.15 and 415 g/cc are discussed, where the average ionization degree of Au ions and the partial densities of different ions in the mixture are determined by the average atom model. It is found that the mixing decreases the energy partition fraction for DT ions significantly even if the number of Au ions is 1.0% of that for DT ions. The mixing also lengthens the range of alpha particles in the plasmas, which is more prominent when Au ion is in a low ionized state. Moreover, the heating of Au ions by alpha particles is found much easier than that of DT ion All these are very harmful to the controlled fusion. All the results about energy partition fractions are mainly because that the heavy Au ion is usually in a highly charged state in the plasmas. This makes the nuclear stopping due to Au ions much bigger than that due to DT ions and cover the incident energy range for the heating of DT ions by alpha particles. The similar work in Phys. Plasmas21,102,307 (2014) is found doubtful since its nuclear stopping due to high Z ions was obtained by means of perturbation theory. [ABSTRACT FROM AUTHOR]

The sputtering yields of a tungsten target by hydrogen isotopes in the energy range of bombarding particles from 50 eV to 100 eV, as well as the dependence of the sputtering yields on the angle of incidence of the beam on the target and the energy and angular distributions of sputtered particles are obtained by the code developed by us. The strong influence of the type of surface barrier on the results of calculation of the sputtering yield, as well as on the characteristics of sputtered particles is demonstrated. The results obtained make it possible to more accurately assess the tungsten impurity inflow into the hot plasma zone of tokamak. [ABSTRACT FROM AUTHOR]

The relaxation of relativistic hot electron–positron plasma is investigated by incorporating the effect of non-zero photon mass, and a quadruple Beltrami (QB) relaxed state for the magnetic vector potential is derived. The QB state is a linear superposition of four single force-free fields and is characterized by four self-organized structures of different length scales. The analysis of QB states shows that for certain values of generalized helicities at lower relativistic temperatures, plasma shows diamagnetic behaviour. It is also noteworthy that the inclusion of non-zero photon mass naturally provides the possibility of multiscale structure formation in the relaxed state. In this scenario, one of the field structures is significantly larger than the Compton wavelength of photons, while the other three structures are on the scale of the electron skin depth. The potential implications of this QB state for astrophysical environments are also discussed. [ABSTRACT FROM AUTHOR]

Extragalactic jets are generated as bipolar outflows at the nuclei of active galaxies. Depending on their morphology, they are classified as Fanaroff–Riley type I (FRI) (centre-brightened) and Fanaroff–Riley type II (FRII) (edge-brightened) radio jets. However, this division is not sharp, and observations of these sources at large scales often show intermediate jet morphologies or even hybrid jet morphologies with a FRI type jet on one side and a FRII type jet on the other. A good example of a radio galaxy that is difficult to classify as FRI or FRII is Hercules A. This source shows jets with bright radio lobes (a common feature of FRII type jets) albeit without the hotspots indicative of the violent interaction between the jet and the ambient medium at the impact region, because the jets seem to be disrupted inside the lobes at a distance from the bow shocks surrounding the lobes. In this paper, we explore the jet physics that could trigger this peculiar morphology by means of three-dimensional relativisitic hydrodynamical simulations. Our results show that the large-scale morphological features of Hercules A jets and lobes can be reproduced by the propagation of a relativistically hot plasma outflow that is disrupted by helical instability modes, and generates a hot lobe that expands isotropically against the pressure-decreasing intergalactic medium. We also discuss the implications that this result may have for the host active nucleus in terms of a possible transition from high-excitation to low-excitation galaxy modes. [ABSTRACT FROM AUTHOR]