Initial experimental results of a 35 GHz efficient harmonic amplifier

Summary form only given, as follows. We present initial experimental results of a very compact, high efficiency harmonic amplifier (HARA) prototype. In this experiment, a 6 kV 200 mA pencil electron beam is modulated by a short microwave resonator operating in circular polarization at 5.85 GHz. A 35 GHz output cavity operating at the 6th harmonic of the drive frequency is employed to efficiently extract energy from the modulated beam. This device is expected to deliver 600 watts of output power at 35 GHz with 50% efficiency. Initial experimental results of the beam-wave interactions in the output cavity of the HARA prototype will be presented. The fact that the HARA does not require a beam focusing system makes for a very compact and lightweight system which is well suited for applications where size, weight and efficiency are critical.