Millimeter-wave gyroklystron amplifier experiment using a relativistic electron beam

A fundamental-mode TE/sub 111/ degrees two-cavity intense-beam gyroklystron amplifier experiment, operating at an accelerating voltage of 1 MV, is reported. The two cavities that were tested are designed to serve as bunching cavities for a high-power output cavity. The two-cavity amplifier has demonstrated a linear gain of 15 dB and an unsaturated output power of approximately 40 kW, with the intracavity gain and power approximately 4 dB higher. The frequency of the second cavity has been found to track the frequency of the driven cavity over a range of 300 MHz around a center frequency of 35 GHz. Stable amplifier operation was achieved with beam currents as large as 150 A and a velocity pitch ratio of 0.36. The stable operating range was limited by spurious oscillation in the TE/sub 112/ degrees mode. Theoretical calculations indicate that higher gains might be attainable if this mode could be suppressed.<
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