1,072 research outputs found
Spin induced nonlinearities in the electron MHD regime
We consider the influence of the electron spin on the nonlinear propagation
of whistler waves. For this purpose a recently developed electron two-fluid
model, where the spin up- and down populations are treated as different fluids,
is adapted to the electron MHD regime. We then derive a nonlinear Schrodinger
equation for whistler waves, and compare the coefficients of nonlinearity with
and without spin effects. The relative importance of spin effects depend on the
plasma density and temperature as well as the external magnetic field strength
and the wave frequency. The significance of our results to various plasmas are
discussed.Comment: 5 page
A new electromagnetic wave in a pair plasma
A new nonlinear electromagnetic wave mode in a plasma is reported. Its
existence depends on the interaction of an intense circularly polarized
electromagnetic wave with a plasma, where quantum electrodynamical
photon--photon scattering is taken into account. As an illustration, we
consider a pair plasma and show that the new mode can be significant in
astrophysical settings and in the next generation laser-plasma systems.Comment: 3 page
Generation of wakefields by whistlers in spin quantum magnetoplasmas
The excitation of electrostatic wakefields in a magnetized spin quantum
plasma by the classical as well as the spin-induced ponderomotive force (CPF
and SPF, respectively) due to whistler waves is reported. The nonlinear
dynamics of the whistlers and the wakefields is shown to be governed by a
coupled set of nonlinear Schr\"{o}dinger (NLS) and driven Boussinesq-like
equations. It is found that the quantum force associated with the Bohm
potential introduces two characteristic length scales, which lead to the
excitation of multiple wakefields in a strongly magnetized dense plasma (with a
typical magnetic field strength T and particle density
m), where the SPF strongly dominates over the CPF.
In other regimes, namely T and
m, where the SPF is comparable to the CPF, a plasma wakefield can also
be excited self-consistently with one characteristic length scale. Numerical
results reveal that the wakefield amplitude is enhanced by the quantum
tunneling effect, however it is lowered by the external magnetic field. Under
appropriate conditions, the wakefields can maintain high coherence over
multiple plasma wavelengths and thereby accelerate electrons to extremely high
energies. The results could be useful for particle acceleration at short
scales, i.e. at nano- and micrometer scales, in magnetized dense plasmas where
the driver is the whistler wave instead of a laser or a particle beam.Comment: 8 pages, 2 figures; Revised version to appear in Physics of Plasmas
(Dec. 2010 issue
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