2019ApJ...884...62K

Two-fluid (electron-positron) plasma modeling has shown that inductive acceleration can convert Poynting flux directly into bulk kinetic energy in the relativistic flows driven by rotating magnetized neutron stars and black holes. Here, we generalize this approach by adding an ion fluid. Solutions are presented in which all particles are accelerated as the flow expands, with comparable power channeled into each of the plasma components. In an ion-dominated flow, each species reaches the limiting rigidity, according to Hillas' criterion, in a distance significantly shorter than in a lepton-dominated flow. These solutions support the hypothesis that newly born magnetars and pulsars are potential sources of ultrahigh energy cosmic rays. The competing process of Poynting flux dissipation by magnetic reconnection is shown to be ineffective in low-density flows in which the conventionally defined electron multiplicity satisfies κ_e≲10⁵(4πL₃₈/Ω)^1/4/Max(η_ion^1/2,1), where L₃₈ x 10³⁸ erg s^–1 is the power carried by the flow in a solid angle Ω, and η_ion is the ratio of the ion to lepton power at launch.