Speaker
Arno Vanthieghem
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.4005.pdf
Stability analysis of a periodic system of relativistic current filaments
A. Vanthieghem1,2 , M. Lemoine1 , L. Gremillet3
1 Sorbonne Université, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d’Astrophysique de
Paris, 98 bis bd Arago, 75014 Paris, France
2 Sorbonne Universités, Institut Lagrange de Paris (ILP), 98 bis bd Arago, 75014 Paris, France
3 CEA, DAM, DIF, F-91297 Arpajon, France
Homogeneous counterstreaming plasmas are 12 2
subject to the transverse filamentation (or 1.8
10
1.6
Weibel) instability that leads to the formation
1.4
of magnetically pinched current filaments. The 8
1.2
y [c/ Ωp ]
nonlinear evolution of this instability is of prime
6 1
interest in astrophysics where it is held respon- 0.8
4
sible for generating the magnetic turbulence in 0.6
the precursor region of relativistic collisionless 2
0.4
0.2
shocks [1]. It also plays an important role in
0 0
high-intensity laser-plasma interactions in ac- 0 5 10 15 20 25
t [ Ω-1 ]
p
counting for the angular spread of the laser-
Space-time evolution of an initially y-periodic
accelerated particles [2].
chain of current filaments in a plasma composed
In this presentation, we perform a linear sta-
of two counterstreaming pair beams. The lat-
bility analysis of a periodic system of relativis- ter drift along the x-axis, and are described by
tic current filaments described by a relativistic Jüttner-Synge distributions of proper tempera-
warm-fluid model. Using the Floquet theory, we ture T0 = me c2 and Lorentz factor γ0 = 10. Space
compute the exact eigenmodes of the system, and time coordinates are normalized by the rela-
and show that the dominant modes transit from tivistic plasma frequency Ω p associated with the
coalescence-type to kink-type instabilities with peak density of a single electron beam .
increasing nonlinearity and asymmetry between the plasma streams. Our theoretical predictions
are supported by particle-in-cell simulations. In a strongly nonlinear symmetric configuration,
the stationary state consists of a chain of Harris-type current sheets, for which we derive a new
analytic expression for the relativistic kink instability. This formula closely matches the numer-
ical results, and allows us to delimit the coalescence and kink-dominated parameter regions.
References
[1] M. Milosavljevic and E. Nakar, Astrophys. J. 641, 978 (2006)
[2] A. Debayle, J.J. Honrubia, E. d’Humières and V.T. Tikhonchuk, Phys. Rev. E 82, 036405 (2010)
