Modulational instability of magnetosonic waves in a spin 1/2 quantum plasma

Journal Article · Thu May 15 04:00:00 EDT 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2913265· OSTI ID:21120290

Misra, A P ^[1]; Shukla, P K ^[2]

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1. Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan-731 235 (India)
2. Institut fuer Theoretische Physik IV and Centre for Plasma Science and Astrophysics, Fakultaet fuer Physik and Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

The modulational instability (MI) of magnetosonic waves (MSWs) is analyzed, by using a two-fluid quantum magnetohydrodynamic model that includes the effects of the electron-1/2 spin and the plasma resistivity. The envelope modulation is then studied by deriving the corresponding nonlinear Schroedinger equation from the governing equations. The plasma resistivity is shown to play a dissipative role for the onset of MI. In the absence of resistivity, the microscopic spin properties of electrons can also lead to MI. In such a situation, the dominant spin contribution corresponds to a dense quantum plasma with the particle number density, n{sub 0} > or approx. 10{sup 28} m{sup -3}. Also, in such a dissipative (absorbing) medium, where the group velocity vector is usually complex for real values of the wave vector, the role of the real group velocity in the propagation of one-dimensional MSW packets in a homogeneous absorbing medium is reported. The effects of quantum spin on the stability/instability conditions of the magnetosonic envelope are obtained and examined numerically. From the nonlinear dispersion relation of the modulated wave packet it is found that the effect of the spin (plasma resistivity) is to decrease (increase) the instability growth rate provided the normalized Zeeman energy does not exceed a critical value. The theoretical results may have relevance to astrophysical (e.g., magnetars) as well as to ultracold laboratory plasmas (e.g., Rydberg plasmas)

• OSTI ID: 21120290
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ASTROPHYSICS
COLD PLASMA
DISPERSION RELATIONS
ELECTRONS
INSTABILITY
INSTABILITY GROWTH RATES
ION ACOUSTIC WAVES
MAGNETOACOUSTIC WAVES
MAGNETOHYDRODYNAMICS
NONLINEAR PROBLEMS
ONE-DIMENSIONAL CALCULATIONS
PLASMA DENSITY
QUANTUM PLASMA
SCHROEDINGER EQUATION
SPIN
VECTORS
VELOCITY
WAVE PACKETS