ABSTRACTWe describe a measurement of the transient conductivity induced in amorphous SiO2during irradiation by an intense and energetic electron beam. Preliminary results of an experiment [1] we performed at the Pulsed High - Energy Radiographic Machine Emitting X Rays (PHERMEX) facility of Los Alamos National Laboratory indicate that a beam of electrons of energy 17.5 MeV, of current density 1 kA/cm2, and of micropulse duration 3 nsec induce in a-SiO2an electric conductivity 007E 6 × 10-3(03A9-cm)-1. This value is 15 orders of magnitude larger than the ordinary (ionic) conductivity of the material [2].