Cut-off conditions and existence domains for large-amplitude ion-acoustic solitons and double layers in fluid plasmas

1990 ◽  
Vol 44 (1) ◽  
pp. 1-23 ◽  
Author(s):  
S. Baboolal ◽  
R. Bharuthram ◽  
M. A. Hellberg
Keyword(s):  
Negative Ion ◽  
Double Layers ◽  
Sagdeev Potential ◽  
Ion Acoustic ◽  
Negative Ion Plasmas ◽  
Ion Acoustic Solitons ◽  
Arbitrary Amplitude ◽  
Ion Species ◽  
Positive Ion

It is shown how existence domains for arbitrary-amplitude ion-acoustic solitons and double layers are determined numerically by cut-off conditions on the corresponding Sagdeev potential. A two-electron-temperature model is considered, and in positive-ion plasmas the cut-off conditions are given in terms of the electron parameters, while for negative-ion plasmas such conditions are described in terms of parameters characterizing the role of the negative ion species.

On the existence of ion-acoustic double layers in negative-ion plasmas

1991 ◽  
Vol 46 (2) ◽  
pp. 247-254 ◽  
Author(s):  
S. Baboolal ◽  
R. Bharuthram ◽  
M. A. Hellberg
Keyword(s):  
Negative Ion ◽  
Double Layers ◽  
Positive Ions ◽  
Potential Formulation ◽  
Ion Acoustic ◽  
Negative Ion Plasmas ◽  
Temperature Electron ◽  
Arbitrary Amplitude ◽  
Ion Acoustic Double Layers ◽  
Ion Species

It is well known that ion-acoustic double layers occur in plasmas containing two-temperature electron species and positive ions. In a recent study Verheest suggested that such structures can occur when there is only one electron species but both negative and positive ion species. There a stationary modified Korteweg de Vries equation was derived to support his deduction. This prediction, however, contradicts our own arbitrary-amplitude studies, which also cover the Verheest parameter regime. Here we resolve the discrepancy by examining both approaches in the pseudo-potential formulation in more relevant detail. The implications of this study extend beyond the realm of the present subject.

Large-amplitude ion-acoustic double layers in multispecies plasma

1990 ◽  
Vol 68 (6) ◽  
pp. 474-478 ◽  
Author(s):  
S. L. Jain ◽  
R. S. Tiwari ◽  
S. R. Sharma
Keyword(s):  
Large Amplitude ◽  
Reductive Perturbation Method ◽  
Negative Ion ◽  
Double Layers ◽  
Ion Acoustic ◽  
Unmagnetized Plasma ◽  
Ion Acoustic Double Layers ◽  
Ion Species ◽  
Ion Impurity ◽  
Positive Ion

We have investigated the effect of second-ion species on the characteristics of a large-amplitude ion-acoustic double layers (IADL) in a collisionless, unmagnetized plasma consisting of hot and cold Maxwellian populations of electrons and two cold-ion species with different masses, concentrations, and charge states. After deriving the criteria for the existence of large-amplitude IADL, we find that the presence of a positive-ion impurity does not modify considerably the characteristics of large-amplitude IADL. However, the presence of a negative-ion impurity changes significantly the characteristics of large-amplitude IADL. We have also presented an analytic discussion of small-amplitude IADL using a reductive perturbation method.

Linear and nonlinear obliquely propagating ion-acoustic waves in magnetized negative ion plasma with non-thermal electrons

2013 ◽  
Vol 79 (5) ◽  
pp. 893-908 ◽  
Author(s):  
M. K. MISHRA ◽  
S. K. JAIN
Keyword(s):  
Acoustic Waves ◽  
Kdv Equation ◽  
Negative Ions ◽  
Ion Concentration ◽  
Negative Ion ◽  
Slow Mode ◽  
Ion Temperature ◽  
Ion Acoustic ◽  
Ion Acoustic Solitons ◽  
Ion Species

AbstractIon-acoustic solitons in magnetized low-β plasma consisting of warm adiabatic positive and negative ions and non-thermal electrons have been studied. The reductive perturbation method is used to derive the Korteweg–de Vries (KdV) equation for the system, which admits an obliquely propagating soliton solution. It is found that due to the presence of finite ion temperature there exist two modes of propagation, namely fast and slow ion-acoustic modes. In the case of slow-mode if the ratio of temperature to mass of positive ion species is lower (higher) than the negative ion species, then there exist compressive (rarefactive) ion-acoustic solitons. It is also found that in the case of slow mode, on increasing the non-thermal parameter (γ) the amplitude of the compressive (rarefactive) soliton decreases (increases). In fast ion-acoustic mode the nature and characteristics of solitons depend on negative ion concentration. Numerical investigation in case of fast mode reveals that on increasing γ, the amplitude of compressive (rarefactive) soliton increases (decreases). The width of solitons increases with an increase in non-thermal parameters in both the modes for compressive as well as rarefactive solitons. There exists a value of critical negative ion concentration (αc), at which both compressive and rarefactive ion-acoustic solitons appear as described by modified KdV soliton. The value of αc decreases with increase in γ.

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