Experimental Demonstration of a W-Band Sheet Beam Klystron

As an important proof experiment for further developing a compact sheet beam klystron with the multicavity, multi-gap interaction circuit, we have designed and built a uniform magnetic focusing prototype tube, where a simulated 55 kV, 2.2 A sheet beam transports an interaction length of about 100 mm. A water-cooled solenoid is used to produce the field with a maximum value of 4,000 Gauss. To improve the characteristic impedance and efficiency, the HF circuit is composed of four multi-gap cavities, and each cavity includes a multi-layered membrane to finely tune its working frequency. Meanwhile, to simplify the structure, a single-port scheme is applied in the input and output cavities, the adverse influence of which on the field uniformity is reduced to a minimum level. The latest hot test shows the maximum output power attains to 2.57 kW at 95.025 GHz and the bandwidth is about 100 MHz when the output is over 1 kW. The self-oscillation has not been observed in this experiment.