Low fluence calculation of photoelectron flux densities outside an emitting sphere

A method for calculating the flux of photoelectrons emerging from a surface, in a force-free environment, is described. The flux is constructed from the energy and angular distribution of the electrons at the surface and represents a particular solution to a class of time dependent solutions of the collisionless force-free Boltzman equation. Detailed calculations are made for a sphere emitting photoelectrons over half its surface due to the passage of a plane X-ray of finite time duration.