Space and time-dependent return current in secondary plasma created in atmosphere by a short pulse ultrarelativistic high power electron beam

Possibilities provided to energy propagation in atmosphere by short pulse high power electron beams, in the ns range, are presently being actively explored. Among the physical variables which condition dynamical beam equilibrium as well as stability, a prime place is held by secondary plasma current neutralization factor fm=∥Jplasmall/∥Jbeam∥. Theoretical models have until now included this quantity in the form of a given space and time constant, considered as some kind of average.