Date : 27th of September, 2016 at 14:00
Speaker : Dr. Kazem Ardaneh
Title : COLLISIONLESS ELECTRON-ION SHOCKS IN RELATIVISTIC UNMAGNETIZED JET-AMBIENT INTERACTIONS
Abstract :
The course of non-thermal electron ejection in relativistic unmagnetized electron?
ion shocks is investigated by performing self-consistent particle-in-cell simulations.
The shocks are excited through the injection of a relativistic jet into ambient plasma,
leading to two distinct shocks ( referred to as the trailing shock and leading shock)
and a contact discontinuity. The Weibel-like instabilities heat the electrons up
to approximately half of the ion kinetic energy. The double layers formed in the trailing
and leading edges then accelerate the electrons up to the ion kinetic energy.
The electron distribution function in the leading edge shows a clear,
non-thermal power-law tail which contains ~ 1% of electrons and
~ 8% of the electron energy. Its power-law index is -2.6.
The acceleration efficiency is ~ 23% by number and ~ 50% by energy,
and the power-law index is -1.8 for the electron distribution
function in the trailing edge. The effect of the dimensionality is examined
by comparing the results of threedimensional simulations
with those of two-dimensional simulations.
The comparison demonstrates that electron acceleration
is more effi cient in two dimensions.