SOLITONS IN THE CRAB-NEBULA

High resolution x-ray observations of the Crab Nebula show the existen ce of a well-defined bright torus. A straightforward estimate suggests the inadequacy of the conventional model for the pulsar-wind terminal shock. A resolution to this difficulty is given in this report; it is proposed that the pulsar-wind shock can only be ''thermalized'' in a collisionless fashion and hence the shock transition is bound to be br oad. A dynamical scenario is given regarding how the shock ''thermaliz ation'' should proceed, and it employs the excitation of solitons that serve as the energy carriers in transporting the pulsar wind energy a far and depositing the energy when certain conditions in the backgroun d plasmas are met. A necessary condition for such an energy-deposition process to occur is that the charateristic wave speed decreases with distance, a condition that can hold in the Crab Nebula.