Effect of Collisional Energy Loss on Ionization Growth in H2

A model is studied for the growth of ionization in H2 gas with a constant electric field. The model includes a feature that stipulates an electron loses a fixed energy per collision with an H2 molecule, independent of the electron energy. Exact solutions are obtained for the time-growing part of the electron distribution function, averaged over velocity orientation, for the case that zero-energy electrons are uniformly supplied through all space at time zero. It is argued that this model provides a reasonable description of physical reality for E/P > ∼200.