A two-beam virtual cathode device

Two concepts using counterstreaming high-space-charge relativistic electron beams are described. In one concept, two counterstreaming electron beams are injected into a drift beam. Depending on their current and energy, either zero, one, or two virtual cathodes are formed. In some cases (when the current of each beam is half the space charge limit current IL), the two beams take turns ´forming a virtual cathode. Applications to high-power microwave generation and collective ion acceleration are indicated.