scholarly journals Electron acoustic solitons in the presence of an electron beam and superthermal electrons

2011 ◽  
Vol 18 (5) ◽  
pp. 627-634 ◽  
Author(s):  
S. Devanandhan ◽  
S. V. Singh ◽  
G. S. Lakhina ◽  
R. Bharuthram
Keyword(s):  
Electron Beam ◽  
Mach Number ◽  
Electric Field ◽  
Potential Method ◽  
Hot Electrons ◽  
Superthermal Electron ◽  
Electrons And Ions ◽  
Arbitrary Amplitude ◽  
Unmagnetized Plasma ◽  
Electron Acoustic

Abstract. Arbitrary amplitude electron acoustic solitons are studied in an unmagnetized plasma having cold electrons and ions, superthermal hot electrons and an electron beam. Using the Sagdeev pseudo potential method, theoretical analysis is carried out by assuming superthermal hot electrons having kappa distribution. The results show that inclusion of an electron beam alters the minimum value of spectral index, κ, of the superthermal electron distribution and Mach number for which electron-acoustic solitons can exist and also changes their width and electric field amplitude. For the auroral region parameters, the maximum electric field amplitudes and soliton widths are found in the range ~(30–524) mV m−1 and ~(329–729) m, respectively, for fixed Mach number M = 1.1 and for electron beam speed of (660–1990) km s−1.

scholarly journals Electron acoustic solitary waves with non-thermal distribution of electrons

2004 ◽  
Vol 11 (2) ◽  
pp. 275-279 ◽  
Author(s):  
S. V. Singh ◽  
G. S. Lakhina
Keyword(s):  
Solitary Waves ◽  
Auroral Zone ◽  
Thermal Electron ◽  
Electrons And Ions ◽  
Cold Electrons ◽  
Field Lines ◽  
Unmagnetized Plasma ◽  
Zone Field ◽  
Electron Acoustic ◽  
Pseudo Potential

Abstract. Electron-acoustic solitary waves are studied in an unmagnetized plasma consisting of non-thermally distributed electrons, fluid cold electrons and ions. The Sagdeev pseudo-potential technique is used to carry out the analysis. The presence of non-thermal electrons modifies the parametric region where electron acoustic solitons can exist. For parameters representative of auroral zone field lines, the electron acoustic solitons do not exist when either α > 0.225 or Tc/Th > 0.142, where α is the fractional non-thermal electron density, and Tc (Th) represents the temperature of cold (hot) electrons. Further, for these parameters, the simple model predicts negatively charged potential structures. Inclusion of an electron beam in the model may provide the positive potential solitary structures.

Electron acoustic double layers in a magnetized plasma in the presence of superthermal particles

2019 ◽  
Vol 85 (3) ◽  
Author(s):  
D. Dutta ◽  
K. S. Goswami
Keyword(s):  
Acoustic Waves ◽  
Small Amplitude ◽  
Analytical Study ◽  
Potential Method ◽  
Magnetized Plasma ◽  
Double Layers ◽  
Electrons And Ions ◽  
Mach Numbers ◽  
Electron Acoustic ◽  
Pseudo Potential

An analytical study of the small amplitude electron acoustic double layers in a magnetized plasma consisting of superthermal electrons and ions along with cold fluid electrons is discussed. The dispersion relation allows electron acoustic waves with the frequency within electron and ion gyro-frequency in the modelled plasma. In the process of study of the nonlinear structures, the Sagdeev pseudo-potential method for small amplitude regions is employed. The existence domains for the double layers are investigated in terms of the Mach numbers of the structures and the temperature ratios of the species for different ratios of their concentration. The effects of the compositional parameters on the nature and size of the double layers are also explored and it is observed that the plasma can support both compressive and rarefactive double layers depending on the values of those parameters and the Mach numbers.

Nonlinear electron-acoustic rogue waves in electron-beam plasma system with non-thermal hot electrons

2014 ◽  
Vol 54 (9) ◽  
pp. 1786-1792 ◽  
Author(s):  
S.A. Elwakil ◽  
A.M. El-hanbaly ◽  
A. Elgarayh ◽  
E.K. El-Shewy ◽  
A.I. Kassem
Keyword(s):  
Electron Beam ◽  
Rogue Waves ◽  
Hot Electrons ◽  
Plasma System ◽  
Beam Plasma ◽  
Electron Acoustic ◽  
Electron Beam Plasma

Electron-acoustic instability driven by a field-aligned hot electron beam

1991 ◽  
Vol 46 (1) ◽  
pp. 1-10 ◽  
Author(s):  
R. Bharuthram
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Electron Beam ◽  
Hot Electron ◽  
Plasma Parameters ◽  
Acoustic Instability ◽  
Electrons And Ions ◽  
Component Plasma ◽  
Instability Growth ◽  
Electron Acoustic

Using kinetic theory, the electron-acoustic instability is investigated in a three-component plasma consisting of a hot electron beam and stationary cool electrons and ions. In the model considered here both the electrons and ions are magnetized, with the beam drift along the external magnetic field. The dependence of the growth rate on plasma parameters, such as electron-beam density, electron-beam speed, magnetic field strength and propagation angle, is studied. In addition, the effects of anisotropies in the velocity distributions of the hot electron beam and the cool electrons on the instability growth rate are examined.

scholarly journals Double layers in the downward current region of the aurora

2003 ◽  
Vol 10 (1/2) ◽  
pp. 45-52 ◽  
Author(s):  
R. E. Ergun ◽  
L. Andersson ◽  
C. W. Carlson ◽  
D. L. Newman ◽  
M. V. Goldman
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Phase Space ◽  
Electric Field ◽  
Electric Fields ◽  
Double Layers ◽  
Parallel Electric Field ◽  
Electrostatic Waves ◽  
Current Region ◽  
Decisive Evidence

Abstract. Direct observations of magnetic-field-aligned (parallel) electric fields in the downward current region of the aurora provide decisive evidence of naturally occurring double layers. We report measurements of parallel electric fields, electron fluxes and ion fluxes related to double layers that are responsible for particle acceleration. The observations suggest that parallel electric fields organize into a structure of three distinct, narrowly-confined regions along the magnetic field (B). In the "ramp" region, the measured parallel electric field forms a nearly-monotonic potential ramp that is localized to ~ 10 Debye lengths along B. The ramp is moving parallel to B at the ion acoustic speed (vs) and in the same direction as the accelerated electrons. On the high-potential side of the ramp, in the "beam" region, an unstable electron beam is seen for roughly another 10 Debye lengths along B. The electron beam is rapidly stabilized by intense electrostatic waves and nonlinear structures interpreted as electron phase-space holes. The "wave" region is physically separated from the ramp by the beam region. Numerical simulations reproduce a similar ramp structure, beam region, electrostatic turbulence region and plasma characteristics as seen in the observations. These results suggest that large double layers can account for the parallel electric field in the downward current region and that intense electrostatic turbulence rapidly stabilizes the accelerated electron distributions. These results also demonstrate that parallel electric fields are directly associated with the generation of large-amplitude electron phase-space holes and plasma waves.

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