Speaker
Mohamad Shalaby
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.4014.pdf
Accessing the Nonlinear Physics of Astrophysical Plasmas
Mohamad Shalaby1,2 , Avery E. Broderick1,3 , Philip Chang4 ,
Christoph Pfrommer5 , Astrid Lamberts6 and Ewald Puchwein7
Astrophysical plasmas are ubiquitous and differ from laboratory plasmas in key aspects. They
are typically cold kB T me c2 , collisionless, and usually contain relativistic sub-populations. To
study the evolution of such plasmas, typically, it is necessary to employ a fully kinetic treatment
of the plasmas, as described by Boltzmann equation coupled with Maxwell’s equations.
-0.5
This can be accomplished via Particle-in-cell (PIC) -1.0
-1.5
algorithms, which combine Eulerian and Lagrangian
-2.0
methods to efficiently solve for plasmas full evolution. -2.5
-3.0
Due to numerical heating in PIC algorithms, exploring -3.5
nonlinear and long term (e.g., millions of ω p−1 ) evolu- -4.0
2
tion is typically unreliable. However, the use of higher 0
order interpolation (up to 5th order spline) has been -2
shown to be a key in increasing the accuracy of the -4
coupling between the Eulerian and Lagrangian parts -6
0.5 1.0 1.5 2.0 2.5 3.0 3.5
of the algorithm and thus ensuring long term stability
(without the need to resolve the Debye length in some
instances) [1]. This greatly improves energy conservation while exactly conserving both the
charge and the total momentum. I have developed a fully relativistic PIC codes (called SHARP),
in 1D [1], 1D3V, 2D and 2D3V, where up to fifth order spline shape function are implemented.
The computation cost of using SHARP codes are much lower than using higher resolution sim-
ulations with typical (1st or 2nd order) interpolation to achieve comparable accuracy. Thus,
SHARP codes enable the reliable explorations of the nonlinear evolution of astrophysical plas-
mas. In my talk, I will present some results where these codes have been used to study the
nonlinear evolution of tenuous beam-plasmas instabilities [2] .
References
[1] Shalaby, M., Broderick, A. E., Chang, P., et al. 2017, ApJ, 841, 52
[2] Broderick, A. E., Chang, P., & Pfrommer, C. 2012, ApJ, 752, 22
1 Perimeter Institute for Theoretical Physics, Waterloo, Canada. 2 University of Chicago, USA. 3 University of Wa-
terloo, Canada. 4 University of Wisconsin-Milwaukee, USA. 5 Leibniz Institute for Astrophysics, Potsdam, Ger-
many. 6 California Institute of Technology, USA. 7 University of Cambridge, UK.
