scholarly journals Simulation of High-Voltage Ion Diode with Wire Cathode at Atmospheric Pressure of Nitrogen

2021 ◽  
Vol 26 (1) ◽  
Author(s):  
Olha Volodymyrivna Andriienko ◽  
Mykhailo Serhiiovych Melnichenko ◽  
Serhii Borysovych Sydorenko ◽  
Anatolii Ivanovych Kuzmychiev
Keyword(s):  
High Voltage ◽  
Voltage Drop ◽  
Electronic Conductivity ◽  
Charged Particles ◽  
Negative Ions ◽  
Constant Field ◽  
Gas Temperature ◽  
Positive Ions ◽  
Interelectrode Gap ◽  
Metal Cathode

Physic-topological simulation of a high-voltage coaxial ion diode with a wire metal cathode at atmospheric nitrogen pressure in the hydrodynamic drift-diffusion approximation is performed. The reactions of nitrogen ionization by electrons, attachment of electrons to nitrogen molecules with the formation of negative ions, recombination of charged particles with opposite signs of charge, secondary ion-electron emission of the cathode were taken into account. The distribution of potential and density (concentration) of charged particles in the interelectrode gap, the density of ionic and electron currents at the electrodes were calculated within the self-consistent problem with the following parameters: diameter of wire metal cathode 0.01-0.16 mm, diameter of tubular anode 6 or 20 cm, voltage 20-40 kV, gas temperature 300 or 600K. The influence of geometry, voltage and gas temperature on the discharge parameters has been determined. The obtained calculated data on the discharge current are consistent with the experiment. It is shown that two zones are formed in the discharge between the electrode gap – one is with a width of about 1 mm with a strong and rapidly changing electric field near the cathode and the second long zone with the drift of charged particles towards the anode with a smaller but constant field strength. This is a characteristic feature of negative corona discharges. In the cathode zone there is an intensive ionization of nitrogen with the generation of positive ions and electrons. In the second zone, the density of positive ions decreases sharply due to recombination and weak ionization. The reaction of attachment of electrons to nitrogen molecules begins almost near the cathode surface and continues throughout the cathode zone, in the drift zone the concentration of negative ions gradually decreases. Moreover, the role of electronic conductivity is greatly reduced as we approach the anode. Due to the low mobility of negative ions and, accordingly, the high electrical resistance of the drift zone, the voltage drop on this space part represents a significant portion of the discharge voltage (~1.5 kV on the cathode zone and 18.5 kV on the drift space, at the total voltage of 20 kV). The fact that the highest concentration of positive ions is formed near the cathode, and negative – along the entire interelectrode gap, it can be used, respectively, in the processes of ionic nitriding of wire cathode metal materials and for processing materials and biological substances (bacteria, viruses, fungi), sensitive to negative ions, at the location of the carriers of these substances near the anode. To implement the latter, it is advisable to modify the design of the external anode for efficient extraction of nitrogen ions into the environment. It is also advisable to continue research in the direction of increasing the energy efficiency of ion generation by determining the method of the maximum allowable reduction of the voltage drop on the space of drift of charged particles.

scholarly journals Electrosmosis between plane parallel walls produced by high-frequency alternating currents

1937 ◽  
Vol 163 (913) ◽  
pp. 298-317 ◽  
Keyword(s):  
Electric Field ◽  
Solid Surface ◽  
High Frequency ◽  
Negative Ions ◽  
The Body ◽  
Mathematical Treatment ◽  
Constant Field ◽  
Electrostatic Forces ◽  
Plane Parallel ◽  
Positive Ions

The problem of the motion, under the influence of high-frequency alter­nating currents, of fluid between plane parallel walls whose distance apart is very small, appears to be of interest in certain branches of Physical Chemistry. The following paper contains a mathematical treatment of this type of motion under certain specified conditions. We are greatly indebted to Mr. J. J. Bikerman of the Chemistry Department of the University of Manchester for having brought the problem to our notice, and for having given us a great deal of information concerning the physics of the phenomena involved. In general, when two different substances, or phases, have a common surface, there is an electrokinetic potential difference between them. This is produced by an electric double layer of ions in contact with the common surface. Consider the boundary between a solid and an electrolyte, and let us assume the solid to take a negative charge, as is almost invariably the case when the electrolyte is water or a very dilute aqueous solution. The negative layer consists, probably, of ions adsorbed rigidly to the surface. Near the surface, in the fluid, there will be a preponderance of positively charged ions held more or less firmly in position by electrostatic forces. Very close to the “rigid” layer of negative ions the electrostatic forces will be sufficiently great to keep the positive ions rigidly in place. As we leave the solid surface the forces diminish and ultimately a position is reached where diffusion and thermal forces overcome the electrostatic forces. Beyond this surface in the fluid there will still be a preponderance of positive ions, since the electrostatic forces will still be operative, but these ions will be mobile. At points remote from the solid surface there are approximately equal concentrations of positive and negative ions, and the liquid as a whole is electrically neutral. The equilibrium attained when electrostatic and diffusion forces are operating was first calculated by Gouy; the expression given by Gouy for the charge density is used in this paper. On applying an electric field the mobile ions in the layer near the surface begin to move towards one or other of the two electrodes as illustrated diagramatically in fig. 1, and this motion is transmitted to the liquid as a whole through the operation of viscous forces. As the fluid close to the walls contains more positive ions than negative ions greater forces will be called into play near the walls than in the body of the fluid, and, in a constant field, the liquid will move to the cathode. This phenomenon of the movement of a liquid over a fixed surface under the influence of an applied electric field is called “electrosmosis” or “endosmosis”.

Numerical Simulation of Leakage Current on Conductive Insulator Surface

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.

scholarly journals Effect of Low-Pressure Plasma Treatment Parameters on Wrinkle Features

Materials ◽  
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.

scholarly journals Effect of External Charging on Nanoparticle Formation in a Flame

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2891
Author(s):  
Elena Fomenko ◽  
Igor Altman ◽  
Igor E. Agranovski
Keyword(s):  
Negative Ions ◽  
Formation Processes ◽  
Particle Charge ◽  
Mgo Nanoparticles ◽  
Nanoparticle Formation ◽  
Noticeable Change ◽  
Nanoparticle Shape ◽  
Positive Ions ◽  
Direct Interpretation ◽  
Shape Of Nanoparticles

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.

scholarly journals Electrical Breakdown in Air and in SF6

1995 ◽  
Vol 48 (3) ◽  
pp. 453 ◽  
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.

Note on radiationless transitions involving three-body collisions

1936 ◽  
Vol 32 (3) ◽  
pp. 482-485 ◽  
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.

Chaos in positive ion–negative ion magnetized plasmas

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.

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

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 2–18 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 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>

Comparison of the Forward Voltage Drop of Si and SiC High Voltage Diodes

2014 ◽  
Vol 64 (7) ◽  
pp. 223-236 ◽  
Author(s):  
T. Gachovska ◽  
J. L. Hudgins
Keyword(s):  
High Voltage ◽  
Voltage Drop ◽  
Forward Voltage ◽  
Forward Voltage Drop

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

1988 ◽  
Vol 39 (1) ◽  
pp. 71-79 ◽  
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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