High peak power operation of a klystron at a short pulse length

In order to determine the peak power limitation of a typical klystron at short pulse lengths, several Stanford Linear Accelerator klystrons were operated at voltages above their nominal ratings. Using a marx generator to obtain short high-voltage pulses at an impedance level suitable for this experiment, the tubes were operated in the 400-kV region. Appropriate instrumentation was assembled for the measurement of voltage, current, power input, power output and related tube parameters. This paper will discuss tube characteristics, including electronic loading, gain, efficiency and peak output powers as a function of voltage in the 200- to 400-kV range. Measured small-signal characteristics of the tube are compared with computed values. Stable operation was observed at a peak output-power level at 100 MW at a 0.2-µsec pulse length. These results are a step in the direction of providing improved radar range resolution without the time-sidelobe clutter inherent in pulse compression systems.