Experimental confirmation of the reditron concept

A description is given of experiments demonstrating a method for producing high-power microwave emission. The unstable oscillations of a virtual cathode, which forms when a magnetized relativistic electron beam is injected into a circular waveguide, generates the microwave radiation. In contrast to other virtual-cathode microwave-generation techniques, electrons in the waveguide are prevented from reflexing back into the diode region by use of a slotted range-thick anode. Electrons injected into the waveguide are guided through the slot by an applied magnetic field, while reflected electrons, under the proper conditions, are intercepted by the anode. Several advantages of this approach are described, and experimental confirmation of this mode of high-power microwave generation is demonstrated. Data showing frequency scaling with beam parameters and magnetic field are also presented. Using this technique, 1.4 GW was produced at 3.9 GHz with several hundred megawatts radiated in harmonic radiation