OPERATION OF A K-BAND 2ND-HARMONIC COAXIAL GYROKLYSTRON

Amplification studies of a two-cavity second harmonic gyroklystron wit h a coaxial input cavity and drift tube are reported. The inner conduc tor is supported by tungsten pins which intercept the beam, and it uti lizes lossy dielectric rings to enhance mode suppression. A double-ano de magnetron injection gun produces a 440 kV, 200-268 A, 1 mus beam wi th an average perpendicular-to-parallel velocity ratio near one. The T E011 input cavity is driven near 9.886 GHz and the TE021 output cavity resonates near 19.772 GHz. Peak powers near 30 MW have been achieved, although more easily reproducible peak powers hover closer to 20 MW. While stability is improved over previous devices, beam interception r educes the accessible range in parameter space and thus degrades ampli fier performance. Pin erosion is also evident and qualitatively agrees well with theoretical predictions.