Dynamical quantum chaos as fluid turbulence
Journal
Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics
Journal Volume
57
Journal Issue
4
Pages
4150-4154
Date Issued
1998
Author(s)
Abstract
We present a critical examination of the ideal MHD model for the stationary Crab pulsar wind, which has a terminal ow Lorentz factor and may have a terminal ratio of Poynting ux to kinetic c = D 106 energy ux as low as p D 10~210~3. We rst show that transitions to a low-p conguration cannot occur gradually in regions well beyond the light cylinder where the ow has already become ultrarelativistic. This is because the poloidal eld lines do not expand sufficiently beyond the fast critical point to convert the electromagnetic energy into ow kinetic energy. As an alternative, we consider whether the acceleration may proceed abruptly, with the ow rapidly passing through the fast critical point and expanding into a low-p conguration. Such rapid expansion of eld lines, analogous to that in a de Laval nozzle, requires the poloidal elds to be highly compressed upstream of the fast critical point. We categorize the rapid eld expansion generally into two prototypes : sheetlike and fountain-like, with the former being a spontaneous transition and the latter requiring external pressure supports. Unfortunately, it is shown that both types of rapid acceleration fail to satisfy either the energy and momentum conservation or the MHD ux-freezing condition. Nevertheless, we have pinned down the only situation where a stationary, ideal-MHD low-p wind may exist. It requires almost the entire wind acceleration to occur in the immediate neighborhood of the light cylinder. Moreover, it also demands drastic modications to the conventional picture of the pulsar dipole magnetosphere, in that the outer magnetosphere must be dominated by the toroidal elds and that the pulsar wind is carried by only a small fraction of the magnetospheric eld lines emerging from the star.
SDGs
Type
journal article