The theoretical problem of the transient behavior of a plasma injected, at constant current, into a trap‐free semiconductor is solved exactly. Coincident with the arrival of the propagating injected‐plasma front at the collecting electrode there is a cusp in the time‐derivative‐of‐the‐voltage‐vs‐time profile. At any instant of time, the relative field‐intensity distribution within the injected plasma region is the same as in the steady state.