Plasma sheath evolution from perturbed electrodes in a negative-ion plasma. Part 2. Experiment and PIC simulation

1997 ◽  
Vol 58 (3) ◽  
pp. 455-466 ◽  
Author(s):  
SEUNGJUN YI ◽  
YASSER EL-ZEIN ◽  
KARL E. LONNGREN ◽  
TERENCE E. SHERIDAN
Keyword(s):  
Fluid Model ◽  
Negative Ions ◽  
Plasma Sheath ◽  
Negative Ion ◽  
Pic Simulation ◽  
Particle In Cell ◽  
Model Code ◽  
Positive Ions ◽  
Ion Plasma ◽  
Quasineutral Plasma

The two-dimensional spatial and temporal evolution of a plasma surrounding an electrode whose potential is suddenly decreased is experimentally investigated. The electrode contains a localized convex or a localized concave perturbation. The quasineutral plasma consists of positive ions and various proportions of negative ions and electrons. The results are compared and contrasted with those that are obtained numerically using a particle-in-cell (PIC) simulation and those that had previously been obtained using a fluid-model code.

Plasma sheath evolution from perturbed electrodes in a negative-ion plasma

1997 ◽  
Vol 57 (1) ◽  
pp. 47-57 ◽  
Author(s):  
YASSER EL-ZEIN ◽  
SEUNGJUN YI ◽  
KARL E. LONNGREN ◽  
IGOR ALEXEFF ◽  
TERRENCE E. SHERIDAN ◽  
...  
Keyword(s):  
Temporal Evolution ◽  
Negative Ions ◽  
Plasma Sheath ◽  
Negative Ion ◽  
Two Dimensional ◽  
Positive Ions ◽  
Ion Plasma ◽  
Quasineutral Plasma

The two-dimensional spatial and temporal evolution of the components of a plasma surrounding an electrode whose potential is suddenly decreased is investigated numerically. The electrode contains a localized convex or a localized concave voltage perturbation. The quasineutral plasma consists of positive ions and various proportions of negative ions and electrons. The results are compared and contrasted with those obtained with a uniform electrode under identical plasma conditions.

scholarly journals Effect of DC Biased Voltage and Ion Temperature on Bounded Ion-Ion Plasma

2020 ◽  
Vol 25 (1) ◽  
pp. 61-67
Author(s):  
Anish Maskey ◽  
Atit Deuja ◽  
Suresh Basnet ◽  
Raju Khanal
Keyword(s):  
Electric Field ◽  
Strong Electric Field ◽  
Negative Ions ◽  
Simulation Method ◽  
Negative Ion ◽  
Ion Temperature ◽  
Plasma Parameters ◽  
Degree Of Ionization ◽  
Particle In Cell ◽  
Ion Plasma

 A one dimensional particle-in-cell (PIC) simulation method has been employed to study the effect of DC voltage and ion temperature on the properties of ion-ion plasma bounded by two symmetrical but oppositely biased electrodes. It is assumed that the ion-ion plasma is collisionless and both the positive and negative ion species have the same mass, temperature, and degree of ionization. Simulation results show that the formation of sheath and presheath regions and fluctuation of plasma parameters in that region are affected by the biasing voltage and ion temperature. It was found that the magnitude of the electrostatic electric field at the vicinity of biasing electrodes was affected by the biasing voltage and ion temperature as well. This strong electric field close to the electrodes further prevents the flow of charged particles towards the electrodes. The presence of a non-zero electric field at the quasineutral region suggests a presheath region similar to the electron-ion plasma. In the quasineutral region, the density of ions increased with the increase in biasing voltage and decreased with the increase in temperature of isothermal ions. Furthermore, the phase space diagrams for the ions were obtained which indicated different regions of the plasma. The positive ions acquire negative velocity towards the negatively biased electrode and the negative ions acquire positive velocity towards the positively biased electrode.

The Boltzmann relation in electronegative plasmas: When is it permissible to use it?

2000 ◽  
Vol 64 (2) ◽  
pp. 131-153 ◽  
Author(s):  
R. N. FRANKLIN ◽  
J. SNELL
Keyword(s):  
Fluid Model ◽  
Negative Ions ◽  
Ionization Rate ◽  
Negative Ion ◽  
Simple Relationship ◽  
Ion Temperature ◽  
Ion Density ◽  
Positive Ions ◽  
Electronegative Plasmas ◽  
Low Pressures

This paper reports the results of computations to obtain the spatial distributions of the charged particles in a bounded active plasma dominated by negative ions. Using the fluid model with a constant collision frequency for electrons, positive ions and negative ions the cases of both detachment-dominated gases (such as oxygen) and recombination-dominated gases (such as chlorine) are examined. It is concluded that it is valid to use a Boltzmann relation ne = ne0exp(eV/kT) for the electrons of density ne, where the temperature T is approximately the electron temperature Te, and that the density nn of the negative ions at low pressures obeys nn = nn0exp(eV/kTn), where Tn is the negative-ion temperature. However, at high pressure in detachment-dominated gases where the ratio of negative-ion density to electron density is constant and greater than unity, and when the attachment rate is larger than the ionization rate, the negative ions are distributed with the same effective temperature as the electrons. In all other cases there is no simple relationship. Thus to put nn/ne = const, nn = ne0exp(eV/kTe) and nn = nn0exp(eV/kTn) simultaneously is mathematically inconsistent and physically unsound. Accordingly, expressions deduced for ambipolar diffusion coefficients based on these assumptions have no validity. The correct expressions for the situation where nn/ne = const are obtained without invoking a Boltzmann relation for the negative ions.

Current-driven drift wave instability in a collisional dusty negative ion plasma

2013 ◽  
Vol 79 (6) ◽  
pp. 1113-1116 ◽  
Author(s):  
M. ROSENBERG
Keyword(s):  
Negative Ions ◽  
Negative Ion ◽  
Drift Waves ◽  
Charged Dust ◽  
Wave Instability ◽  
Nonuniform Plasma ◽  
Positive Ions ◽  
Ion Plasma ◽  
The Magnetic Field ◽  
Linear Kinetic Theory

AbstractThe excitation of drift waves by an electron current parallel to the magnetic field is investigated in a nonuniform plasma composed of electrons, positive ions, negative ions, and massive, negatively charged dust. Electrostatic drift waves with frequencies smaller than the ion gyrofrequencies and wavelengths larger than the ion gyroradii are considered. Linear kinetic theory is used, and collisions of charged particles with neutrals are taken into account. The present results may be relevant to laboratory collisional magnetoplasmas containing negative ions and dust.

Low-frequency electrostatic waves in a magnetized, current-free, heavy negative ion plasma

2013 ◽  
Vol 79 (6) ◽  
pp. 1107-1111 ◽  
Author(s):  
S. H. KIM ◽  
R. L. MERLINO ◽  
J. K. MEYER ◽  
M. ROSENBERG
Keyword(s):  
Large Fraction ◽  
Low Frequency ◽  
Negative Ions ◽  
Wave Mode ◽  
Negative Ion ◽  
Electrostatic Wave ◽  
Electrostatic Waves ◽  
Positive Ions ◽  
Ion Plasma ◽  
The Waves

AbstractWe report experimental observations of a low-frequency (≪ ion gyrofrequency) electrostatic wave mode in a magnetized cylindrical (Q machine) plasma containing positive ions, very few electrons and a relatively large fraction (n−/ne > 103) of heavy negative ions (m−/m+ ≈ 10), and no magnetic field-aligned current. The waves propagate nearly perpendicular to B with a multiharmonic spectrum. The maximum wave amplitude coincided spatially with the region of largest density gradient suggesting that the waves were excited by a drift instability in a nearly electron-free positive ion–negative ion plasma

Drift instability in a positive ion–negative ion plasma

2013 ◽  
Vol 79 (5) ◽  
pp. 949-952 ◽  
Author(s):  
M. ROSENBERG ◽  
R. L. MERLINO
Keyword(s):  
Negative Ions ◽  
Local Approximation ◽  
Magnetized Plasma ◽  
Negative Ion ◽  
Positive Ions ◽  
Ion Plasma ◽  
Drift Instability ◽  
Ion Species ◽  
Positive Ion ◽  
Linear Kinetic Theory

AbstractDrift wave instability in a magnetized plasma composed of positive ions and negative ions is considered using linear kinetic theory in the local approximation. We consider the case where the mass (temperature) of the negative ions is much larger (smaller) than that of the positive ions, and where the gyroradii of the two ion species are comparable. Weak collisional effects are taken into account. Application to possible laboratory parameters is discussed.

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.

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