The role of negative ions on the Jeans instability in a complex plasma in the presence of nonthermal positive ions

2006 ◽  
Vol 13 (10) ◽  
pp. 102904 ◽  
Author(s):  
Banamali Roy ◽  
Susmita Sarkar ◽  
Manoranjan Khan ◽  
M. R. Gupta
Keyword(s):  
Negative Ions ◽  
Complex Plasma ◽  
Positive Ions ◽  
Jeans Instability

scholarly journals Orientational instability of the director in a nematic cell caused by electro-induced anchoring modification

2021 ◽  
Vol 24 (1) ◽  
pp. 13601
Author(s):  
O.S. Tarnavskyy ◽  
M.F. Ledney
Keyword(s):  
Liquid Crystal ◽  
Negative Ions ◽  
The Other ◽  
Cell Surfaces ◽  
Positive Ions ◽  
Threshold Voltages ◽  
A Cell ◽  
Director Reorientation ◽  
Orientational Transitions

We theoretically investigate the threshold for the director reorientation from the homeotropic state to the hybrid homeotropic-planar state and vice versa in a cell filled with a flexoelectric nematic liquid crystal (NLC) subjected to an electric field. The liquid crystal is doped by a CTAB-like substance, a part of molecules of which dissociates into positive and negative ions. The anchoring on one of the cell surfaces is assumed to be strong and homeotropic, while the other surface can adsorb positive ions which play the role of an orienting surfactant for NLC molecules on this surface. At certain voltages, the orientational transitions in the bulk of the NLC are possible due to the changing conditions for the director on the adsorbing surface. We calculate respective threshold voltages as functions of anchoring parameters. The existence of the critical values of these parameters, beyond which the orientational transitions do not take place, is established.

Jeans instability in a complex plasma in the presence of negative ions

2006 ◽  
Vol 73 (5) ◽  
pp. 506-510 ◽  
Author(s):  
Susmita Sarkar ◽  
Banamali Roy ◽  
M Khan ◽  
M R Gupta
Keyword(s):  
Negative Ions ◽  
Complex Plasma ◽  
Jeans Instability

scholarly journals Characterisation of corona-generated ions used in a Neutral cluster and Air Ion Spectrometer (NAIS)

2011 ◽  
Vol 4 (2) ◽  
pp. 2099-2125 ◽  
Author(s):  
H. E. Manninen ◽  
A. Franchin ◽  
S. Schobesberger ◽  
A. Hirsikko ◽  
J. Hakala ◽  
...  
Keyword(s):  
Detection Limit ◽  
Size Range ◽  
Negative Ions ◽  
Neutral Cluster ◽  
Differential Mobility ◽  
Size Spectra ◽  
Mixing Ratios ◽  
Positive Ions ◽  
Concentration Of Ions

Abstract. We characterized size and chemical composition of ions generated by a corona-needle charger of a Neutral cluster and Air Ion Spectrometer (NAIS) by using a high resolution differential mobility analyzer and a time-of-flight mass spectrometer. Our study is crucial to verify the role of corona-generated ions in the particle size spectra measured with the NAIS, in which a corona charger is used to charge aerosol particles down to the size range overlapping with the size of generated ions. The size and concentration of ions produced by the corona discharging process depend both on corona voltage and on properties and composition of carrier gas. Negative ions were <1.6 nm (0.8 cm2 V−1 s−1 in mobility) in all tested gas mixtures (nitrogen, air with variable mixing ratios of water vapour), whereas positive ions were <1.7 nm (0.7 cm2 V−1 s−1. Electrical filtering of the corona-generated ions and not removing all charged particles plays an important role in determining the lowest detection limit. Based on our experiments, the lowest detection limit for the NAIS in the particle mode is between 2 and 3 nm.

The role of negative ions in experiments with complex plasma

JETP Letters ◽  
2003 ◽  
Vol 78 (5) ◽  
pp. 300-304 ◽  
Author(s):  
B. A. Klumov ◽  
A. V. Ivlev ◽  
G. Morfill
Keyword(s):  
Negative Ions ◽  
Complex Plasma

scholarly journals Characterisation of corona-generated ions used in a Neutral cluster and Air Ion Spectrometer (NAIS)

2011 ◽  
Vol 4 (12) ◽  
pp. 2767-2776 ◽  
Author(s):  
H. E. Manninen ◽  
A. Franchin ◽  
S. Schobesberger ◽  
A. Hirsikko ◽  
J. Hakala ◽  
...  
Keyword(s):  
Detection Limit ◽  
Size Range ◽  
Negative Ions ◽  
Neutral Cluster ◽  
Differential Mobility ◽  
Size Spectra ◽  
Mixing Ratios ◽  
Positive Ions ◽  
Concentration Of Ions

Abstract. We characterized size and chemical composition of ions generated by a corona-needle charger of a Neutral cluster and Air Ion Spectrometer (NAIS) by using a high resolution differential mobility analyzer and a time-of-flight mass spectrometer. Our study is crucial to verify the role of corona-generated ions in the particle size spectra measured with the NAIS, in which a corona charger is used to charge aerosol particles down to the size range overlapping with the size of generated ions. The size and concentration of ions produced by the corona discharging process depend both on corona voltage and on properties and composition of carrier gas. Negative ions were <1.6 nm (0.8 cm2 V−1 s−1 in mobility) in all tested gas mixtures (nitrogen, air with variable mixing ratios of water vapour), whereas positive ions were <1.7 nm (0.7 cm2 V−1 s−1). Electrical filtering of the corona generated ions and not removing all charged particles plays an important role in determining the lowest detection limit. Based on our experiments, the lowest detection limit for the NAIS in the particle mode is between 2 and 3 nm.

Gaussian- and Slater-type bases for ground and certain low-lying excited states of positive and negative ions of the atoms H through Xe based on the generator coordinate Hartree–Fock method

1996 ◽  
Vol 74 (8) ◽  
pp. 1526-1534 ◽  
Author(s):  
A.B.F. da Silva ◽  
M. Trsic
Keyword(s):  
Excited States ◽  
Negative Ions ◽  
Weight Functions ◽  
Slater Type ◽  
Atomic Ions ◽  
Hartree Fock ◽  
Gaussian Type ◽  
Positive Ions ◽  
Generator Coordinate

We applied a discretized version of the generator coordinate Hartree–Fock (GCHF) method to generate Gaussian- and Slater-type functions for mono positive and mono negative ions of the atoms H through Xe. The basis sizes for Slater-type functions are (12s, 10p, 10d) for positive ions, and (13s, 11p, 10d) for negative ions. In the case of Gaussian-type functions the bases are (18s, 12p, 11d) for both positive and negative species. Ground and excited state Hartree–Fock energies are calculated with these bases and the results compared with the best atom-optimized calculations and numerical HF results available. A discussion on the role of weight functions in the evaluation of electronic energies emphasizes the integral character of the GCHF method. Key words: Slater-type bases, Gaussian-type bases, generator coordinate Hartree–Fock, atomic ions.

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.

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