Speaker
Antoine Bret
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/O2.J302.pdf
Generation of Laser-Driven, High-Mach-Number Magnetized
Collisionless Shocks
D.B. Schaeffer1 , W. Fox1,2 , D. Haberberger3 , G. Fiksel4 , A. Bhattacharjee1,2 , D.H. Barnak3 ,
S.X. Hu3 , K. Germaschewski5 , R.K. Follett3
1 Princeton University, Princeton, USA
2 Princeton Plasma Physics Laboratory, Princeton, USA
3 Laboratory for Laser Energetics, Rochester, USA
4 University of Michigan, Ann Arbor, USA
5 University of New Hampshire, Durham, USA
Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of su-
percritical shocks is of particular importance due to their role in accelerating particles to high
energies. While these shocks have been traditionally studied by spacecraft and remote sensing
observations, laboratory experiments can provide reproducible and multi-dimensional datasets
that provide complementary understanding of the underlying microphysics. We present exper-
iments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation
and evolution of high-Mach number collisionless shocks created through the interaction of a
laser-driven magnetic piston and magnetized ambient plasma [1, 2]. Through time-resolved, 2-
D imaging we observe large density and magnetic compressions that propagate at an Alfvénic
Mach number MA ∼ 15 and that occur over ion kinetic length scales. Additional shock structure
and electron and ion heating are observed with optical Thomson scattering, which is also used to
characterize the initial ambient plasma. Particle-in-cell simulations constrained by experimental
data further detail the shock formation and separate dynamics of the multi-ion-species ambient
plasma. The results show that the shocks form on timescales as fast as one gyroperiod, aided
by the efficient coupling of energy, and the generation of a magnetic barrier, between the piston
and ambient ions. The development of this experimental platform opens the way for controlled
laboratory investigations of high-Mach-number collisionless shocks, including mechanisms of
shock heating and particle acceleration.
References
[1] D.B. Schaeffer, W. Fox, D. Haberberger, et al., Phys. Rev. Lett. 119, 025001 (2017)
[2] D.B. Schaeffer, W. Fox, D. Haberberger, et al., Phys. Plasmas 24, 122702 (2017)
