Plasma Parameters and Weakly Non-Ideal Behaviour of a High Density, Super-Atmospheric 2kA Cascade Arc in Argon

AbstractExperimental results are reported for simultaneous pressure and current pulses up to 14 bar and 2200 A superimposed on an atmospheric pressure 60 A dc cascade arc. A current density over 108 A/m2, previously 107 A/m2 (power density 1012W m3, previously 1010W/m3) has been obtained. The electron temperature of the thermal plasma was deduced from the end-on measured radiance of argon lines, and the electron density from the absolute continuum emission. The values found for the quantities mentioned during the quasi-stationary phase of the current pulse, lasting ~ 1 ms, were 27000 K and 3 · 1023 m-3, respectively, at a pressure of ~ 1.5 bar (ionization degree 100%), and 18000 K and > 1024 m-3, respectively, for a pressure of 14 bar (ionization degree 60%). These values satisfy the LTE relation. Deviations from the Spitzer conductivity have been observed in this weakly non-ideal plasma.In general, the high ionized thermal plasma studied with its composition of neutral, singly ionized and doubly ionized argon atoms can serve as a useful medium for spectroscopic studies of highly ionized systems and as a valuable source of radiation in the visible a well as in the near and far ultraviolet parts of the spectrum.

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Spectroscopic Studies of Laser-Based Far-Ultraviolet Plasma Light Source

Applied Sciences ◽

10.3390/app11156919 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6919

Author(s):

Majid Masnavi ◽

Martin Richardson

Keyword(s):

Dense Plasma ◽

Wavelength Region ◽

Spectroscopic Studies ◽

Radiation Hydrodynamics ◽

Full Width ◽

Half Maximum ◽

Laser Plasmas ◽

Series Of Experiments ◽

Far Ultraviolet ◽

Radiation Conversion

A series of experiments is described which were conducted to measure the absolute spectral irradiances of laser plasmas created from metal targets over the wavelength region of 123–164 nm by two separate 1.0 μm lasers, i.e., using 100 Hz, 10 ns, 2–20 kHz, 60–100 ns full-width-at-half-maximum pulses. A maximum radiation conversion efficiency of ≈ 3%/2πsr is measured over a wavelength region from ≈ 125 to 160 nm. A developed collisional-radiative solver and radiation-hydrodynamics simulations in comparison to the spectra detected by the Seya–Namioka-type monochromator reveal the strong broadband experimental radiations which mainly originate from bound–bound transitions of low-ionized charges superimposed on a strong continuum from a dense plasma with an electron temperature of less than 10 eV.

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Inkjet Printing of Polypyrrole Electroconductive Layers Based on Direct Inks Freezing and Their Use in Textile Solid-State Supercapacitors

Materials ◽

10.3390/ma14133577 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3577

Author(s):

Zbigniew Stempien ◽

Mohmmad Khalid ◽

Marcin Kozanecki ◽

Paulina Filipczak ◽

Angelika Wrzesińska ◽

...

Keyword(s):

Solid State ◽

Inkjet Printing ◽

Surface Resistance ◽

Spectroscopic Studies ◽

Polymerization Temperature ◽

Textile Fabrics ◽

Symmetric Supercapacitor ◽

Novel Method ◽

A Current ◽

Standard Support

In this work, we propose a novel method for the preparation of polypyrrole (PPy) layers on textile fabrics using a reactive inkjet printing technique with direct freezing of inks under varying temperature up to −16 °C. It was found that the surface resistance of PPy layers on polypropylene (PP) fabric, used as a standard support, linearly decreased from 6335 Ω/sq. to 792 Ω/sq. with the decrease of polymerization temperature from 23 °C to 0 °C. The lowest surface resistance (584 Ω/sq.) of PPy layer was obtained at −12 °C. The spectroscopic studies showed that the degree of the PPy oxidation as well as its conformation is practically independent of the polymerization temperature. Thus, observed tendences in electrical conductivity were assigned to change in PPy layer morphology, as it is significantly influenced by the reaction temperature: the lower the polymerization temperature the smoother the surface of PPy layer. The as-coated PPy layers on PP textile substrates were further assembled as the electrodes in symmetric all-solid-state supercapacitor devices to access their electrochemical performance. The electrochemical results demonstrate that the symmetric supercapacitor device made with the PPy prepared at −12 °C, showed the highest specific capacitance of 72.3 F/g at a current density of 0.6 A/g, and delivers an energy density of 6.12 Wh/kg with a corresponding power density of 139 W/kg.

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Thermodynamic of Liquid Iron Ore Reduction by Hydrogen Thermal Plasma

Metals ◽

10.3390/met8121051 ◽

2018 ◽

Vol 8 (12) ◽

pp. 1051 ◽

Cited By ~ 4

Author(s):

Masab Naseri Seftejani ◽

Johannes Schenk

Keyword(s):

Iron Oxide ◽

Liquid Iron ◽

Thermal Plasma ◽

Iron Ore ◽

Hydrogen Plasma ◽

Reduction Rate ◽

Plasma Arc ◽

Ionization Degree ◽

Reduction Reactions ◽

Plasma State

The production of iron using hydrogen as a reducing agent is an alternative to conventional iron- and steel-making processes, with an associated decrease in CO2 emissions. Hydrogen plasma smelting reduction (HPSR) of iron ore is the process of using hydrogen in a plasma state to reduce iron oxides. A hydrogen plasma arc is generated between a hollow graphite electrode and liquid iron oxide. In the present study, the thermodynamics of hydrogen thermal plasma and the reduction of iron oxide using hydrogen at plasma temperatures were studied. Thermodynamics calculations show that hydrogen at high temperatures is atomized, ionized, or excited. The Gibbs free energy changes of iron oxide reductions indicate that activated hydrogen particles are stronger reducing agents than molecular hydrogen. Temperature is the main influencing parameter on the atomization and ionization degree of hydrogen particles. Therefore, to increase the hydrogen ionization degree and, consequently, increase of the reduction rate of iron ore particles, the reduction reactions should take place in the plasma arc zone due to the high temperature of the plasma arc in HPSR. Moreover, the solubility of hydrogen in slag and molten metal are studied and the sequence of hematite reduction reactions is presented.

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Prospects for observing the magnetorotational instability in the plasma Couette experiment

Journal of Plasma Physics ◽

10.1017/s0022377815000471 ◽

2015 ◽

Vol 81 (4) ◽

Cited By ~ 4

Author(s):

K. Flanagan ◽

M. Clark ◽

C. Collins ◽

C. M. Cooper ◽

I. V. Khalzov ◽

...

Keyword(s):

Stability Analysis ◽

Body Force ◽

Protoplanetary Disks ◽

Azimuthal Velocity ◽

Relevant Parameter ◽

Magnetorotational Instability ◽

Plasma Parameters ◽

Global Stability Analysis ◽

Two Fluid ◽

Ideal Plasma

Many astrophysical disks, such as protoplanetary disks, are in a regime where non-ideal, plasma-specific magnetohydrodynamic (MHD) effects can significantly influence the behaviour of the magnetorotational instability (MRI). The possibility of studying these effects in the plasma Couette experiment (PCX) is discussed. An incompressible, dissipative global stability analysis is developed to include plasma-specific two-fluid effects and neutral collisions, which are inherently absent in analyses of Taylor–Couette flows (TCFs) in liquid metal experiments. It is shown that with boundary driven flows, a ion-neutral collision drag body force significantly affects the azimuthal velocity profile, thus limiting the flows to regime where the MRI is not present. Electrically driven flow (EDF) is proposed as an alternative body force flow drive in which the MRI can destabilize at more easily achievable plasma parameters. Scenarios for reaching MRI relevant parameter space and necessary hardware upgrades are described.

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Modeling the Influence of the Penetration Channel’s Shape on Plasma Parameters When Handling Highly Concentrated Energy Sources

Advances in Materials Science and Engineering ◽

10.1155/2017/2435079 ◽

2017 ◽

Vol 2017 ◽

pp. 1-8

Author(s):

Dmitriy N. Trushnikov ◽

Ekaterina S. Salomatova ◽

Igor I. Bezukladnikov ◽

Igor L. Sinani ◽

K. P. Karunakaran

Keyword(s):

Electron Beam Welding ◽

Gaussian Function ◽

Three Dimensional ◽

Energy Sources ◽

Plasma Parameters ◽

Statistical Probability ◽

Secondary Current ◽

Thermal Fields ◽

Sustained Discharge ◽

A Current

In our work to formulate a scientific justification for process control methods when processing materials using concentrated energy sources, we develop a model that can calculate plasma parameters and the magnitude of the secondary waveform of a current from a non-self-sustained discharge in plasma as a function of the geometry of the penetration channel, thermal fields, and the beam’s position within the penetration channel. We present the method and a numeric implementation whose first stage involves the use of a two-dimensional model to calculate the statistical probability of the secondary electrons’ passage through the penetration channel as a function of the interaction zone’s depth. Then, the discovered relationship is used to numerically calculate how the secondary current changes as a distributed beam moves along a three-dimensional penetration channel. We demonstrate that during oscillating electron beam welding the waveform has the greatest magnitude during interaction with the upper areas of the penetration channel and diminishes with increasing penetration channel depth in a way that depends on the penetration channel’s shape. When the surface of the penetration channel is approximated with a Gaussian function, the waveform decreases nearly exponentially.

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Absolutmessung der kontinuierlichen Strahlung des Heliums im Lichtbogen von λ = 109 bis 540 nm / Measurement of the Helium Continuum Radiation from λ = 109 to 540 nm in an Arc Plasma

Zeitschrift für Naturforschung A ◽

10.1515/zna-1980-0803 ◽

1980 ◽

Vol 35 (8) ◽

pp. 808-819 ◽

Cited By ~ 1

Author(s):

P. Thoma

Keyword(s):

Energy Balance ◽

Theoretical Calculations ◽

Continuum Emission ◽

Kinetic Temperature ◽

Arc Plasma ◽

Plasma Parameters ◽

Continuum Radiation ◽

Theoretical Results ◽

Helium Emission ◽

Good Agreement

Abstract Absolute helium emission coefficients have been measured from 540 nm down to 109 nm in the near vuv. The radiation originates from the axis of a cylindrical He-arc of 2 mm ∅ at one atmosphere with electron temperatures between 25000 K and 26500 K. The electron densities range from 3.0 · 1016 cm-3 to 4.0 · 1016 cm-3 and have been determined independently from other plasma parameters by means of line shape measurements. The density of atoms and their kinetic temperature have been calculated from the energy balance of the electrons and Dalton's law. Comparison of the measured helium continuum emission coefficients with theoretical calculations in the wavelength range from 540 nm to 400 nm shows that, in this experiment, the radiation due to bremsstrahlung in the field of atoms must not be neglected. Taking into account this contribution very good agreement with theoretical calculations over the whole investigated spectral range from 540 nm down to 109 nm has been found. Thus the present experiment confirms the theoretical results for the photoionisation coefficients from the n = 2 and n = 3 levels. On the basis of these results the helium continuum radiation may be used for calibration purposes, which is of particular interest in the vuv.

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Relations Between FUV Excess and Coronal Soft X-Ray Emission Among Dwarf Stars

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2017.47 ◽

2017 ◽

Vol 34 ◽

Cited By ~ 7

Author(s):

Graeme H. Smith ◽

Mason Hargrave ◽

Elliot Eckholm

Keyword(s):

Active Regions ◽

Continuum Emission ◽

Stellar Rotation ◽

Dwarf Stars ◽

X Ray ◽

Contrast Detection ◽

Chromospheric Emission ◽

Far Ultraviolet

AbstractThe far-ultraviolet magnitudes of late-F, G and early-K dwarfs with (B − V) ⩾ 0.50 as measured by the GALEX satellite are shown to correlate with soft X-ray luminosity. This result indicates that line and continuum emission from stellar active regions make significant contributions to the flux in the GALEX FUV band for late-F, G and K dwarfs. By contrast, detection of a correlation between FUV brightness and soft X-ray luminosity among early-F dwarfs requires subtraction of the photospheric component from the FUV flux. The range in (B − V) among F and G dwarfs over which a correlation between uncorrected FUV magnitude and X-ray luminosity is detected coincides with the range in colour over which coronal and chromospheric emission correlates with stellar rotation.

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Effects of Precursors and Plasma Parameters on Fullerene Synthesis in RF Thermal Plasma Reactor

Plasma Chemistry and Plasma Processing ◽

10.1007/s11090-006-9036-0 ◽

2006 ◽

Vol 26 (6) ◽

pp. 597-608 ◽

Cited By ~ 20

Author(s):

János Szépvölgyi ◽

Zoran Marković ◽

Biljana Todorović-Marković ◽

Zoran Nikolić ◽

Ilona Mohai ◽

...

Keyword(s):

Thermal Plasma ◽

Plasma Reactor ◽

Plasma Parameters ◽

Rf Thermal Plasma

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Dust-driven viscous ring-instability in protoplanetary disks

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731878 ◽

2018 ◽

Vol 609 ◽

pp. A50 ◽

Cited By ~ 24

Author(s):

C. P. Dullemond ◽

A. B. T. Penzlin

Keyword(s):

Surface Density ◽

Scattered Light ◽

Protoplanetary Disks ◽

Continuum Emission ◽

Rotational Instability ◽

Local Pressure ◽

Ionization Degree ◽

Local Maxima ◽

Gas Ionization ◽

Small Dust

Protoplanetary disks often appear as multiple concentric rings in dust continuum emission maps and scattered light images. These features are often associated with possible young planets in these disks. Many non-planetary explanations have also been suggested, including snow lines, dead zones and secular gravitational instabilities in the dust. In this paper we suggest another potential origin. The presence of copious amounts of dust tends to strongly reduce the conductivity of the gas, thereby inhibiting the magneto-rotational instability, and thus reducing the turbulence in the disk. From viscous disk theory it is known that a disk tends to increase its surface density in regions where the viscosity (i.e. turbulence) is low. Local maxima in the gas pressure tend to attract dust through radial drift, increasing the dust content even more. We have investigated mathematically if this could potentially lead to a feedback loop in which a perturbation in the dust surface density could perturb the gas surface density, leading to increased dust drift and thus amplification of the dust perturbation and, as a consequence, the gas perturbation. We find that this is indeed possible, even for moderately small dust grain sizes, which drift less efficiently, but which are more likely to affect the gas ionization degree. We speculate that this instability could be triggered by the small dust population initially, and when the local pressure maxima are strong enough, the larger dust grains get trapped and lead to the familiar ring-like shapes. We also discuss the many uncertainties and limitations of this model.

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