Efficient Operation of Traveling-Wave Tube Amplifier with Dynamically Adjusted Collector Bias Voltages

We describe a novel efficiency enhancement technique for traveling-wave tube amplifiers (TWTAs) for applications in digital communication systems. The enhancement is obtained by tracking the time-dependent power envelope of the input waveform and dynamically adjusting the bias voltages of the TWTs multi-stage depressed collector. The instantaneous amplitude of the input waveform is used as a guide to optimize the collector bias voltages to the particular energy distribution of the spent electron beam to achieve maximum energy recovery. The improvement in recovered energy and efficiency has been demonstrated by experiment and through simulation by the large-signal helix TWT code CHRISTINE.