Large-amplitude ion-acoustic double layers in a plasma with warm ions

1990 ◽  
Vol 68 (2) ◽  
pp. 222-226 ◽  
Author(s):  
R. K. Roychoudhury ◽  
Sikha Bhattacharyya ◽  
Y. P. Varshni
Keyword(s):  
Potential Method ◽  
Double Layers ◽  
Ion Temperature ◽  
Sagdeev Potential ◽  
Electron Population ◽  
Numerical Studies ◽  
Ion Acoustic ◽  
Temperature Electron ◽  
Ion Acoustic Double Layers ◽  
Two Temperature

The conditions for the existence of an ion-acoustic double layer in a plasma with warm ions and two distinct groups of hot electrons have been studied using the Sagdeev potential method. A comparison is made with the published results of Bharuthram and Shukla for cold ions and a two-temperature electron population. Numerical studies have been made to find out the effect of a finite ion temperature on the Mach number of the double layers.

Ion acoustic double layers forming behind irradiated solid objects in streaming plasmas

2010 ◽  
Vol 76 (3-4) ◽  
pp. 429-439 ◽  
Author(s):  
W. J. MILOCH ◽  
V. L. REKAA ◽  
H. L. PÉCSELI ◽  
J. TRULSEN
Keyword(s):  
Numerical Simulations ◽  
Uv Light ◽  
Three Dimensional ◽  
Double Layers ◽  
Back Side ◽  
Electron Population ◽  
Von Neumann ◽  
Solid Objects ◽  
Ion Acoustic ◽  
Ion Acoustic Double Layers

AbstractSmall solid metallic objects in relative motion to thermal plasmas are studied by numerical simulations. We analyze supersonic motions, where a distinctive ion wake is formed behind obstacles. At these plasma drift velocities, ions enter the wake predominantly due to deflections by the electric field in the sheath around the obstacle. By irradiating the back side of the object by ultraviolet (UV) light, we can induce also an enhanced photo-electron population there. The resulting charge distribution gives rise to a pronounced local potential and plasma density well behind the object. This potential variation has the form of a three-dimensional ion acoustic double layer, containing also an ion phase space vortex. The analysis is supported also by one-dimensional numerical simulations to illustrate the importance of boundary conditions, Dirichlet and von Neumann conditions in particular.

scholarly journals Particle Energization in Stochastic Double Layers

1985 ◽  
Vol 107 ◽  
pp. 125-129
Author(s):  
William Lotko
Keyword(s):  
Electric Fields ◽  
Acoustic Waves ◽  
Diffusion Processes ◽  
Computer Experiments ◽  
Double Layers ◽  
Ion Temperature ◽  
Ion Drift ◽  
Ion Acoustic ◽  
Relative Electron ◽  
Ion Acoustic Double Layers

Electrostatic turbulence develops in current carrying plasmas when the relative electron-ion drift exceeds the critical value for laminar current flow. Recent 2D computer experiments (Barnes, 1982) indicate that many weak ion acoustic double layers form in such turbulence when the plasma is strongly magnetized (ωce ≳ ωpe), the electron/ion temperature ratio is large (≳10), and the relative electron-ion drift is comparable to or less than the electron thermal speed. The double layers emerge from the incoherent spectrum of electrostatic ion cyclotron and ion acoustic waves as intense localized electric field structures propagating subsonically relative to the ion bulk flow. The occurrence of weak ion acoustic double layers, excited by field-aligned currents in the Earth's auroral regions, has also been reported from in situ spacecraft measurements (Temerin et al., 1982). An important question concerns the effect of these coherent electric fields on plasma transport properties such as bulk heating and acceleration. For example, one might expect nonlinear diffusion processes, manifested as distinct nonthermal features in the particle spectra, to accompany the quasilinear diffusion of ions as they traverse turbulent regions in space. This idea motivates the work presented here.

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.

Ion-acoustic double layers in electron–positron–ion plasmas with finite ion temperature

2013 ◽  
Vol 79 (5) ◽  
pp. 661-675 ◽  
Author(s):  
S. K. JAIN ◽  
M. K. MISHRA
Keyword(s):  
Double Layer ◽  
Small Amplitude ◽  
Double Layers ◽  
Cold Electron ◽  
Ion Temperature ◽  
Temperature Ratio ◽  
Plasma Parameters ◽  
Electron Positron ◽  
Ion Acoustic ◽  
Ion Acoustic Double Layers

AbstractThe large-amplitude ion-acoustic double layers in a collisionless plasma consisting of isothermal positrons, warm adiabatic ions and two-temperature distribution of electrons are investigated. Using the pseudo-potential approach, an energy-integral equation for the system has been derived which encompasses complete nonlinearity for the plasma system. The existence region of the double layers is analyzed numerically. It is found that for a selected set of physical parameters, the rarefactive double layer exists in the electron–positron–ion plasma. It is found that the existence regime of the double layer is very sensitive to the plasma parameters, e.g. cold electron concentration (μ) and temperature ratio of two electron species (β). An increase in the finite ion temperature ratio increases the amplitude of the rarefactive double layer. To study small-amplitude double layers, we have expanded the Sagdeev potential. In the case of small amplitude, it is found that the amplitude of the double layer increases with increase in ion temperature ratio (σ) and cold electron concentration (μ). However increase in positron concentration (α) and temperature ratio of positrons to electrons (γ) decreases the amplitude of the double layer. The effect of various plasma parameters on the characteristics of the double layers is discussed in detail. The results of the investigation may be helpful to understanding basic plasma characteristics in space.

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