  Dreicer generation is one of the main mechanisms of runaway electrons
generation, in particular during tokamak startup. In fully ionized plasma it is
described as a diffusive flow from the Maxwellian core into high energies under
the effect of the electric field. In this work we demonstrate a critical role
of the non-differential nature of inelastic collisions in weakly ionized plasma
during tokamak startup, where some electrons experience virtually no collisions
during acceleration to the critical energy. We show that using the
Fokker-Planck collisional operator can underestimate the Dreicer generation
rate by several orders of magnitude.
