Short rise time intense electron beam generator

A generator is described for producing an intense relativistic electron beam having a short current rise time, the generator comprising: means for generating an intense relativistic input electron beam having a radius r/sub b/, an injected beam current I/sub e/, a density n/sub b/ and a long rise time; a short, cylindrical, electrically conductive drift tube of radius R greater than r/sub b/ and a length greater than about 2.4(R), the tube including: an input end for receiving the input beam; a cavity containing a working gas at a low enough pressure to prevent the input beam from propagating through the working gas before t/sub s/, the time at which the working gas has been ionized by the input beam to a plasma density equal to N/sub b/, the beam being dispersed within the cavity and the space charge limiting current I/sub 1/ being less than I/sub e/; and an output end for passing an intense relativistic output electron beam having a short rise time; and ionizing means for simultaneously and suddenly ionizing the entire volume of the working gas in the drift tube up to a plasma density equal to n/sub b/ after the input beam has been generated and before t/sub s/, thereby generating the output beam