Operation of a high power, X-band gyroklystron experiment

Summary form only given. A high-pulse-power facility to drive X-band gyroklystrons is being operated at the University of Maryland. The rotating beam is produced by a magnetron injection gun (MIG), which is designed to provide pulses of up to 500 kV, 200 A, and 1 μs with low axial velocity spread and perpendicular to axial velocity ratios near 1.5. In the beam test, the microwave tube was replaced with a beam diagnostic chamber. The MIG has been run space-charge limited to 350 kV, 192 A. Temperature-limited operation, while possible over a wide range of parameters, is hindered by spurious microwave oscillations near X-band. Attempts to improve operation by the insertion of lossy dielectrics at the ends of the chamber have been relatively successful. The performance of the metal/ceramic drift tube with regard to the stability of low-order modes was investigated. Experimental results for tube stability as a function of magnetic field and beam voltage were compared to a new start oscillation code which handles the complex tube geometry with the help of a scattering matrix code