Design of a 7 MW, 95 GHz, three-cavity gyroklystron

In this paper we present a three-cavity design of a gyroklystron amplifier at 95 GHz. We present the design of the magnetron injection gun (MIG), the magnetic field coils, and the three-cavity microwave circuit. The MIG produces a 500 kV, 45 A small orbit annular beam with an average perpendicular-to-parallel velocity ratio of 1.5 and a parallel velocity spread below 5% (RMS). The MIG requires a control anode with a voltage of about 65 kV, a magnetic compression of about 30, and a cathode loading near 10 A/cm². The circuit magnetic field is about 28.7 kG. The microwave circuit has a first-harmonic TE ₀₁₁ input cavity which is driven at 47.5 GHz, and second-harmonic TE₀₂₁ buncher and output cavities which are resonant at 95 GHz. A peak power of 7.56 MW is obtained with 51.6 dB gain and 33.6% efficiency. A complete description of the system is presented along with a systematic study of the sensitivity of the device to parametric variations