Effect of External Charging on Nanoparticle Formation in a Flame

This paper attempts to demonstrate the importance of the nanoparticle charge in the synthesis flame, for the mechanism of their evolution during formation processes. An investigation was made of MgO nanoparticles formed during combustion of magnesium particles. The cubic shape of nanoparticles in an unaffected flame allows for direct interpretation of results on the external flame charging, using a continuous unipolar emission of ions. It was found that the emission of negative ions applied to the flame strongly affects the nanoparticle shape, while the positive ions do not lead to any noticeable change. The demonstrated effect emphasizes the need to take into account all of the phenomena responsible for the particle charge when modeling the nanoparticle formation in flames.

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Numerical Simulation of Leakage Current on Conductive Insulator Surface

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.d9759.118419 ◽

2019 ◽

Vol 8 (4) ◽

pp. 9487-9492

Keyword(s):

Numerical Simulation ◽

Electric Field ◽

Leakage Current ◽

Method Of Lines ◽

Electron Attachment ◽

Negative Ions ◽

Conduction Current ◽

Insulator Surface ◽

Finite Difference Approximations ◽

Positive Ions

The outdoor insulator is commonly exposed to environmental pollution. The presence of water like raindrops and dew on the contaminant surface can lead to surface degradation due to leakage current. However, the physical process of this phenomenon is not well understood. Hence, in this study we develop a mathematical model of leakage current on the outdoor insulator surface using the Nernst Planck theory which accounts for the charge transport between the electrodes (negative and positive electrode) and charge generation mechanism. Meanwhile the electric field obeys Poisson’s equation. Method of Lines technique is used to solve the model numerically in which it converts the PDE into a system of ODEs by Finite Difference Approximations. The numerical simulation compares reasonably well with the experimental conduction current. The findings from the simulation shows that the conduction current is affected by the electric field distribution and charge concentration. The rise of the conduction current is due to the distribution of positive ion while the dominancy of electron attachment with neutral molecule and recombination with positive ions has caused a significant reduction of electron and increment of negative ions.

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Effect of Low-Pressure Plasma Treatment Parameters on Wrinkle Features

Materials ◽

10.3390/ma13173852 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3852

Author(s):

Bongjun Gu ◽

Dongwook Ko ◽

Sungjin Jo ◽

Dong Choon Hyun ◽

Hyeon-Ju Oh ◽

...

Keyword(s):

Power Flow ◽

Treatment Time ◽

Argon Plasma ◽

Negative Ions ◽

Low Pressure ◽

Nitrogen Plasma ◽

Pressure Plasma ◽

Positive Ions ◽

Low Pressure Plasma ◽

Optical Adhesive

Wrinkles attract significant attention due to their ability to enhance the mechanical and optical characteristics of various optoelectronic devices. We report the effect of the plasma gas type, power, flow rate, and treatment time on the wrinkle features. When an optical adhesive was treated using a low-pressure plasma of oxygen, argon, and nitrogen, the oxygen and argon plasma generated wrinkles with the lowest and highest wavelengths, respectively. The increase in the power of the nitrogen and oxygen plasma increased the wavelengths and heights of the wrinkles; however, the increase in the power of the argon plasma increased the wavelengths and decreased the heights of the wrinkles. Argon molecules are heavier and smaller than nitrogen and oxygen molecules that have similar weights and sizes; moreover, the argon plasma comprises positive ions while the oxygen and nitrogen plasma comprise negative ions. This resulted in differences in the wrinkle features. It was concluded that a combination of different plasma gases could achieve exclusive control over either the wavelength or the height and allow a thorough analysis of the correlation between the wrinkle features and the characteristics of the electronic devices.

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Electrical Breakdown in Air and in SF6

Australian Journal of Physics ◽

10.1071/ph950453 ◽

1995 ◽

Vol 48 (3) ◽

pp. 453 ◽

Cited By ~ 6

Author(s):

R Morrow ◽

JJ Lowke

Keyword(s):

Electric Field ◽

Electric Field Distribution ◽

Electrical Breakdown ◽

Negative Ions ◽

Continuity Equations ◽

Positive Ions ◽

Positive Space Charge ◽

Attachment Coefficient ◽

Positive Space ◽

Positive Point

A theory is presented for the development of streamers from a positive point in atmospheric air. The continuity equations for electrons, positive ions, and negative ions are solved simultaneously with Poisson's equation. For an applied voltage of 20 kV across a 20 mm gap, streamers are predicted to cross the gap in 26 ns, and the calculated streamer velocities are in fair agreement with experiment. When the gap is increased to 50 mm for the same voltage, the streamer is predicted not to reach the cathode. In this case an intense electric field front rapidly propagates about 35 mm into the gap in 200 ns. For a further 9�5 �s the streamer slowly moves into the gap, until the electric field at the head of the streamer collapses, and the streamer front stops moving. Finally, only positive space-charge remains; this moves away from the point, allowing the field near the point to recover, giving rise to a secondary discharge near the anode. The electric field distribution is shown to be quite different from that found previously for SF6; this is explained by the much lower attachment coefficient in air compared with that in SF6. These results show that streamers in air have a far greater range than streamers in SF6. This greater range cannot be explained by comparison of the values of E*, the electric field at which ionisation equals attachment.

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Note on radiationless transitions involving three-body collisions

Mathematical Proceedings of the Cambridge Philosophical Society ◽

10.1017/s0305004100019186 ◽

1936 ◽

Vol 32 (3) ◽

pp. 482-485 ◽

Cited By ~ 2

Author(s):

R. A. Smith

Keyword(s):

Continuous Spectrum ◽

Negative Ions ◽

Bound State ◽

Excess Energy ◽

Negative Ion ◽

Positive Ions ◽

Continuous State ◽

Direct Formation ◽

Three Body ◽

Positive Ion

When an electron makes a transition from a continuous state to a bound state, for example in the case of neutralization of a positive ion or formation of a negative ion, its excess energy must be disposed of in some way. It is usually given off as radiation. In the case of neutralization of positive ions the radiation forms the well-known continuous spectrum. No such spectrum due to the direct formation of negative ions has, however, been observed. This process has been fully discussed in a recent paper by Massey and Smith. It is shown that in this case the spectrum would be difficult to observe.

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Chaos in positive ion–negative ion magnetized plasmas

Journal of Plasma Physics ◽

10.1017/s0022377820001348 ◽

2020 ◽

Vol 86 (6) ◽

Author(s):

Samiran Ghosh ◽

Biplab Maity ◽

Swarup Poria

Keyword(s):

Nonlinear Wave ◽

Low Frequency ◽

Negative Ions ◽

Dynamical Behaviour ◽

Negative Ion ◽

Sound Waves ◽

Weakly Nonlinear ◽

Positive Ions ◽

Experimental Parameters ◽

Map Analysis

The dynamical behaviour of weakly nonlinear, low-frequency sound waves are investigated in a plasma composed of only positive and negative ions incorporating the effects of a weak external uniform magnetic field. In the plasma model the mass (temperature) of the positive ions is smaller (larger) than that of the negative ions. The dynamics of the nonlinear wave is shown to be governed by a novel nonlinear equation. The stationary plane wave (analytical and numerical) nonlinear analysis on the basis of experimental parameters reveals that the nonlinear wave does have quasi-periodic and chaotic solutions. The Poincarè return map analysis confirms these observed complex structures.

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The Effective Temperature of Dust Impact Plasmas — Olivine Dust on Tungsten Target

10.5194/egusphere-egu21-14909 ◽

2021 ◽

Author(s):

Jiří Pavlů ◽

Samuel Kočiščák ◽

Åshild Fredriksen ◽

Michael DeLuca ◽

Zoltan Sternovsky

Keyword(s):

Negative Charge ◽

Negative Ions ◽

Charge Carriers ◽

Dust Particles ◽

Applied Bias ◽

Control Grid ◽

Impact Speed ◽

Positive Ions ◽

Effective Temperatures ◽

The Impact

<p>We experimentally observe both positive and negative charge carriers in impact plasma and estimate their effective temperatures. The measurements are carried on a dust accelerator using polypyrrole (PPy)-coated olivine dust particles impacting tungsten (W) target in the velocity range of 2&#8211;18 km/s. We measure the retained impact charge as a function of applied bias potential to the control grid. The temperatures are estimated from the data fit. The estimated effective temperatures of the positive ions are approximately 7&#160;eV and seems to be independent of the impact speed. The negative charge carriers' temperatures vary from as low as 1 eV for the lowest speeds to almost ten times higher speeds. The presented values differ significantly from previous studies using Fe dust particles. Yet, the discrepancy can be attributed to a larger fraction of negative ions in the impact plasma that likely originates from the PPy coating.</p>

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Ion-acoustic solitons in multi-component plasmas including negative ions at critical densities

Journal of Plasma Physics ◽

10.1017/s0022377800012861 ◽

1988 ◽

Vol 39 (1) ◽

pp. 71-79 ◽

Cited By ~ 68

Author(s):

Frank Verheest

Keyword(s):

Negative Ions ◽

Stationary Solutions ◽

Reductive Perturbation Method ◽

Positive Ions ◽

Kdv Equations ◽

Basic Fluid ◽

Ion Acoustic ◽

Ion Acoustic Solitons ◽

Modified Kdv Equations ◽

Fast Ion

Ion-acoustic solitons in a plasma with different adiabatic ion constituents and isothermal electrons are studied via a reductive perturbation method. The basic fluid equations then give rise to KdV or modified KdV equations, depending upon the relative ion densities. At critical densities, rarefactive and compressive fast ion-acoustic solitons are possible. Explicit stationary solutions are discussed in the special case of cold ions, in a plasma containing two species of negative ions and one of positive ions. The inclusion of heavier ions, even at low densities, increases the amplitudes of the critical solitons.

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