  The radiation pressure of a radio pulsar does not necessarily disrupt a
surrounding disk. The position of the inner radius of a thin disk around a
neutron star can be estimated by comparing the electromagnetic energy density
generated by the neutron star with the kinetic energy density of the disk.
Inside the light cylinder, the near zone electromagnetic field is essentially
the dipole magnetic field, and the inner radius is the conventional Alfven
radius. Far outside the light cylinder, in the radiation zone, $E=B$ and the
electromagnetic energy density is $<S >/c \propto 1/r^2$ where $S$ is the
Poynting vector. Shvartsman (1970) argued that a stable equilibrium can not be
found in the radiative zone because the electromagnetic energy density
dominates over the kinetic energy density, with the relative strength of the
electromagnetic stresses increasing with radius. In order to check whether this
is true also near the light cylinder, we employ global electromagnetic field
solutions for rotating oblique magnetic dipoles (Deutsch 1955). Near the light
cylinder the electromagnetic energy density increases steeply enough with
decreasing $r$ to balance the kinetic energy density at a stable equilibrium.
The transition from the near zone to the radiation zone is broad. The radiation
pressure of the pulsar can not disrupt the disk for values of the inner radius
up to about twice the light cylinder radius if the rotation axis and the
magnetic axis are orthogonal. This allowed range beyond the light cylinder
extends much further for small inclination angles. We discuss implications of
this result for accretion driven millisecond pulsars and young neutron stars
with fallback disks.
