Rotating Magnetosphere: Acceleration of Plasma from the Surface

We solve for the space-charge field about a rotating object having a monopole magnetic field and a zero work-function surface. We generalize this result to obtain an approximate solution for the case of an axisymmetric dipole field, and find that electrons are accelerated from pulsar-like objects to an energy of the order of E (8ew2a3B /c)112 7 x 10 eV, where w is the rotation rate (estimated 6 rad 5-1), Bp is the polar surface field (estimated 1012 gauss), and a is the radius (estimated 10 m), with most of the acceleration taking place within a distance h (a3w/c)112 140 meters. The overall electromagnetic field structure is essentially unchanged from what one predicts by ignoring particle inertia. In the present work, the effect of a mass difference between the negative and positive particles is ignored. The above injection energy differs from that expected for a neutral stellar wind, and we account for this difference on the basis of the charge-separated nature of the plasma here. Incoherent radiation reaction is examined, and is found to play no important role. Subject headings: hydromagnetics - magnetic stars - plasmas - pulsars