Study of ion-ion plasma formation in negative ion sources by a three-dimensional in real space and three-dimensional in velocity space particle in cell model

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.

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

Journal of Plasma Physics ◽

10.1017/s0022377897006065 ◽

1997 ◽

Vol 58 (3) ◽

pp. 455-466 ◽

Cited By ~ 4

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.

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Analysis of the double-ion plasma in the extraction region in hydrogen negative ion sources

10.1063/1.4792772 ◽

2013 ◽

Cited By ~ 8

Author(s):

T. Fukuyama ◽

S. Okuda ◽

A. Fukano ◽

K. Tsumori ◽

H. Nakano ◽

...

Keyword(s):

Ion Sources ◽

Negative Ion ◽

Extraction Region ◽

Ion Plasma

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Particle-In-Cell Simulations of the Cassini Spacecraft’s Interaction with Saturn’s Ionosphere during the Grand Finale

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab750 ◽

2021 ◽

Author(s):

Zeqi Zhang ◽

Ravindra T Desai ◽

Yohei Miyake ◽

Hideyuki Usui ◽

Oleg Shebanits

Keyword(s):

Three Dimensional ◽

Potential Gradient ◽

Ion Concentration ◽

Negative Ion ◽

High Electron ◽

Free Electrons ◽

Field Orientation ◽

Particle In Cell ◽

Spacecraft Potential ◽

Charged Ions

Abstract A surprising and unexpected phenomenon observed during Cassini’s Grand Finale was the spacecraft charging to positive potentials in Saturn’s ionosphere. Here, the ionospheric plasma was depleted of free electrons with negatively charged ions and dust accumulating up to over 95 % of the negative charge density. To further understand the spacecraft-plasma interaction, we perform a three dimensional Particle-In-Cell study of a model Cassini spacecraft immersed in plasma representative of Saturn’s ionosphere. The simulations reveal complex interaction features such as electron wings and a highly structured wake containing spacecraft-scale vortices. The results show how a large negative ion concentration combined with a large negative to positive ion mass ratio is able to drive the spacecraft to the observed positive potentials. Despite the high electron depletions, the electron properties are found as a significant controlling factor for the spacecraft potential together with the magnetic field orientation which induces a potential gradient directed across Cassini’s asymmetric body. This study reveals the global spacecraft interaction experienced by Cassini during the Grand Finale and how this is influenced by the unexpected negative ion and dust populations.

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On the Analytical Solution of the Kuwabara-Type Particle-in-Cell Model for the Non-Axisymmetric Spheroidal Stokes Flow via the Papkovich–Neuber Representation

Symmetry ◽

10.3390/sym14010170 ◽

2022 ◽

Vol 14 (1) ◽

pp. 170

Author(s):

Panayiotis Vafeas ◽

Eleftherios Protopapas ◽

Maria Hadjinicolaou

Keyword(s):

Stokes Flow ◽

Cell Model ◽

Flow Behavior ◽

Mathematical Formulation ◽

Three Dimensional ◽

Flow Fields ◽

Particle In Cell ◽

Embedded Particles ◽

Type Particle ◽

Spheroidal Geometry

Modern engineering technology often involves the physical application of heat and mass transfer. These processes are associated with the creeping motion of a relatively homogeneous swarm of small particles, where the spheroidal geometry represents the shape of the embedded particles within such aggregates. Here, the steady Stokes flow of an incompressible, viscous fluid through an assemblage of particles, at low Reynolds numbers, is studied by employing a particle-in-cell model. The mathematical formulation adopts the Kuwabara-type assumption, according to which each spheroidal particle is stationary and it is surrounded by a confocal spheroid that creates a fluid envelope, in which the Newtonian fluid moves with a constant velocity of arbitrary orientation. The boundary value problem in the fluid envelope is solved by imposing non-slip conditions on the surface of the spheroid, which is also considered as non-penetrable, while zero vorticity is assumed on the fictitious spheroidal boundary along with a uniform approaching velocity. The three-dimensional flow fields are calculated analytically for the first time, in the spheroidal geometry, by virtue of the Papkovich–Neuber representation. Through this, the velocity and the total pressure fields are provided in terms of a vector and the scalar spheroidal harmonic potentials, which enables the thorough study of the relevant physical characteristics of the flow fields. The newly obtained analytical expressions generalize to any direction with the existing results holding for the asymmetrical case, which were obtained with the aid of a stream function. These can be employed for the calculation of quantities of physical or engineering interest. Numerical implementation reveals the flow behavior within the fluid envelope for different geometrical cell characteristics and for the arbitrarily-assumed velocity field, thus reflecting the different flow/porous media situations. Sample calculations show the excellent agreement of the obtained results with those available for special geometrical cases. All of these findings demonstrate the usefulness of the proposed method and the powerfulness of the obtained analytical expansions.

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