The influence of negatively charged heavy ions on Alfven waves in a cometary environment

2014 ◽  
Vol 4 (3) ◽  
pp. 643-654
Author(s):  
Venugopal Chandu ◽  
Sreekala G ◽  
Sijo Sebastian ◽  
Manesh Michael ◽  
Neethu Theresa Willington ◽  
...  
Keyword(s):  
Heavy Ions ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Loss Cone ◽  
Direction Parallel ◽  
Oxygen Ions ◽  
Oxygen Ion ◽  
Laboratory Plasmas ◽  
Cone Type ◽  
The Stability

Alfven waves are important in a wide variety of areas like astrophysical, space and laboratory plasmas. In cometary environments, waves in the hydromagnetic range of frequencies are excited predominantly by heavy ions. We, therefore, study the stability of Alfven waves in a plasma of hydrogen ions, positively and negatively charged oxygen ions and electrons. Each species has been modeled by drifting distributions in the direction parallel to the magnetic field; in the perpendicular direction the distribution is  simulated with a loss cone type distribution obtained through the subtraction of two Maxwellian distributions with different temperatures.  We find that for frequencies  ( and   being respectively the Doppler shifted and hydrogen ion gyro-frequencies ), the peak growth  rate  increases with increasing negatively charged oxygen ion densities. On the other hand, for frequencies   (being the oxygen ion gyro-frequencies) the region of wave growth increases with increasing negatively charged oxygen ion densities.

scholarly journals Kinetic modulational instability of broadband dispersive Alfvén waves in plasmas

2007 ◽  
Vol 73 (2) ◽  
pp. 153-157 ◽  
Author(s):  
P.K. SHUKLA ◽  
NITIN SHUKLA ◽  
L. STENFLO
Keyword(s):  
Modulational Instability ◽  
Random Phase ◽  
Alfven Waves ◽  
Nonlinear Propagation ◽  
Alfvén Waves ◽  
Nonlinear Dispersion Relation ◽  
Laboratory Plasmas ◽  
Interstellar Media ◽  
Bow Shocks ◽  
Instability Growth

Abstract.We consider a kinetic modulational instability of broadband (random phase) magnetic-field-aligned circularly polarized dispersive Alfvén waves in plasmas. By treating random phase Alfvén waves as quasi-particles, we consider their nonlinear interactions with ion quasi-modes within the framework of the wave-kinetic and Vlasov descriptions. A nonlinear dispersion relation governing such interactions is derived and analyzed. An explicit expression for the kinetic modulational instability growth rate is presented. Our results can be of relevance to the nonlinear propagation of incoherent Alfvén waves, which have been frequently observed in interstellar media, in the solar corona and in the solar wind, as well as in the foreshock regions of planetary bow-shocks and laboratory plasmas.

Acceleration and heating of heavy ions by circularly polarized Alfvén waves

1996 ◽  
Vol 101 (A7) ◽  
pp. 15661-15665 ◽  
Author(s):  
L. Gomberoff ◽  
F. T. Gratton ◽  
G. Gnavi
Keyword(s):  
Heavy Ions ◽  
Alfven Waves ◽  
Alfvén Waves ◽  
Circularly Polarized

scholarly journals Viscoelastic type magnetic effects and self-gravity on the propagation of MHD waves

Meccanica ◽  
2020 ◽  
Vol 55 (11) ◽  
pp. 2199-2214
Author(s):  
Franca Franchi ◽  
Barbara Lazzari ◽  
Roberta Nibbi
Keyword(s):  
Alfven Waves ◽  
Accelerated Expansion ◽  
Mhd Waves ◽  
Critical Threshold ◽  
Alfvén Waves ◽  
Sonic Waves ◽  
The Stability ◽  
Definition Of ◽  
Self Gravity ◽  
Network Patterns

Abstract We take up the challenge to explain the correlation between the Jeans instability topic towards star formation within the accelerated expansion of universe and the role of torsional shear-like Alfven waves in triggering the formation of network patterns, by proposing new mathematical models for self-gravitating interstellar non ideal MHD plasmas. The diffusion of the gravitational field is included via a parabolic Einstein’s equation with the cosmological constant, whereas anomalous resistive features are described through non ideal Ohm’s laws incorporating inertia terms, to account of relaxation and retardation magnetic responses. We perform a spectral analysis to test the stability properties of the novel constitutive settings where dissipative and elastic devices act together, by emphasizing the differences with previous models. As a main result, we highlight the definition of a lower critical threshold, here called the Jeans-Einstein wavenumber, against collapse formation towards the formation of longitudinal gravito-magneto-sonic waves and transverse non gravitational Alfven waves exhibiting larger effective wavespeeds, due to the hyperbolic-parabolic diffusion of the magnetic field. Consequently shorter collisional times are allowable so, beyond the plasma-beta, another interesting key point is the definition of the Ohm number to revisit the timescale topic, towards reviewed Reynolds and Lundquist numbers able to better capture the microphysical phenomena of Magnetic Reconnection in narrow diffusion regimes.

The Stability of the Relativistic Alfvén Waves

1983 ◽  
Vol 23 (2) ◽  
pp. 117-132
Author(s):  
C. D. Ciubotariu ◽  
D. I. Zoler ◽  
N. S. Thirer
Keyword(s):  
Alfven Waves ◽  
Alfvén Waves ◽  
The Stability

Three-dimensional stability of solitary shear kinetic Alfvén waves in a low-beta plasma

1989 ◽  
Vol 41 (1) ◽  
pp. 171-184 ◽  
Author(s):  
K. P. Das ◽  
L. P. J. Kamp ◽  
F. W. Sluijter
Keyword(s):  
Growth Rate ◽  
Dimensional Stability ◽  
Three Dimensional ◽  
Alfven Waves ◽  
Magnetized Plasma ◽  
Alfvén Waves ◽  
Ion Acoustic Solitons ◽  
The Stability ◽  
External Uniform Magnetic Field ◽  
Kinetic Alfvén Waves

The three-dimensional stability of solitary shear kinetic Alfvén waves in a low-β plasma is investigated by the method of Zakharov & Rubenchik (1974). It is found that there is no instability if the direction of perturbation falls within a certain region of space. The growth rate of the instability for the unstable region is determined. This growth rate is found to decrease with increasing angle between the direction of propagation of the solitary wave and the direction of the external uniform magnetic field. A particular case of the present analysis gives results on the stability of ion-acoustic solitons in a magnetized plasma.

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