Characterization of field emitter arrays operating in a traveling wave tube amplifier

Field emitter arrays have shown promise to become a viable electron source for RF vacuum devices, as a replacement of thermionic emitters used almost exclusively to date. Recent results at Northrop Grumman show unmodulated FEA operation in a TWT to over 90 mA and 55 W of RF power at 5 GHz as well as emission-gated operation at 5 mA and 280 mW with the emitted beam RF-modulated at up to 7 GHz. This emission-gated operation demonstrated high levels of modulation with peak-to-average current ratios as high as 1.3. Furthermore, cold measurements of RF coupling to the FEA cathode show that modulation up to and above 20 GHz might be achievable.