The construction of this apparatus follows an initial investigation which has been reported by Weibel. The generator delivers 10 periods of 30 MW at 1.5 Mc to a 10‐&OHgr; load. Alternatively it can give 40 MW at 2 Mc. The technical feasibility of producing hundreds of megawatts for a longer time, as required in some plasma‐physics experiments, is examined.