  A model of an electron-beam-plasma system is introduced to model the
electrical breakdown physics of low-pressure nitrogen irradiated by an intense
pulsed electron beam. The rapidly rising beam current induces an electric field
which drives a return current in the plasma. The rigid-beam model is a
reduction of the problem geometry to cylindrical coordinates and
simplifications to Maxwell's equations that are driven by a prescribed electron
beam current density. The model is convenient for comparing various reductions
of the plasma dynamics and plasma chemistry while maintaining a good
approximation to the overall magnitude of the beam-created electric field. The
usefulness of this model is demonstrated by coupling the rigid-beam model to a
fluid plasma model and a simplified nitrogen plasma chemistry. The dynamics of
this coupled system are computed for a range of background gas pressures, and
the results are compared with experimental measurements. At pressures 1 Torr
and above, the simulated line-integrated electron densities are within a factor
of two of measurements, and show the same trend with pressure as observed in
experiment.
