TY - JOUR
T1 - Departure from MHD prescriptions in shock formation over a guiding magnetic field
AU - Bret, A.
AU - Pe'Er, A.
AU - Sironi, L.
AU - Dieckmann, M. E.
AU - Narayan, R.
N1 - Publisher Copyright:
Copyright © Cambridge University Press 2017.
PY - 2017/9/1
Y1 - 2017/9/1
N2 - In plasmas where the mean-free-path is much larger than the size of the system, shock waves can arise with a front much shorter than the mean-free-path. These so-called collisionless shocks are mediated by collective plasma interactions. Studies conducted so far on these shocks found that although binary collisions are absent, the distribution functions are thermalized downstream by scattering on the fields, so that magnetohydrodynamics prescriptions may apply. Here we show a clear departure from this pattern in the case of Weibel shocks forming over a flow-Aligned magnetic field. A micro-physical analysis of the particle motion in the Weibel filaments shows how they become unable to trap the flow in the presence of too strong a field, inhibiting the mechanism of shock formation. Particle-in-cell simulations confirm these results.
AB - In plasmas where the mean-free-path is much larger than the size of the system, shock waves can arise with a front much shorter than the mean-free-path. These so-called collisionless shocks are mediated by collective plasma interactions. Studies conducted so far on these shocks found that although binary collisions are absent, the distribution functions are thermalized downstream by scattering on the fields, so that magnetohydrodynamics prescriptions may apply. Here we show a clear departure from this pattern in the case of Weibel shocks forming over a flow-Aligned magnetic field. A micro-physical analysis of the particle motion in the Weibel filaments shows how they become unable to trap the flow in the presence of too strong a field, inhibiting the mechanism of shock formation. Particle-in-cell simulations confirm these results.
KW - Collisionless shocks
KW - MHD
KW - Weibel instability
UR - http://www.scopus.com/inward/record.url?scp=85029834936&partnerID=8YFLogxK
U2 - 10.1017/s0263034617000519
DO - 10.1017/s0263034617000519
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AN - SCOPUS:85029834936
SN - 0263-0346
VL - 35
SP - 513
EP - 519
JO - Laser and Particle Beams
JF - Laser and Particle Beams
IS - 3
ER -