Computer simulations of microwave coupling to a nitrogen‐breakdown plasma have been performed at 25 Torr. Nonhydrodynamic ionization fronts are observed to propagate toward the radiation source under a variety of circumstances. Free‐nitrogen‐breakdown simulations in a spherical system show the propagation velocity of the breakdown wave can be as high as 5×106cm/sec. An elementary theory is used for estimating the speed of the breakdown wave in one dimension. The results are in reasonable agreement with breakdown experiments.