The relativistic klystron amplifier with a single output gap [pulsed power applications]

A relativistic klystron amplifier at X-band with a single gap output cavity is designed and tested. The klystron is operated with a pencil beam of 450 keV, 200A extracted from a field immersed diode connected to the electron pulsed accelerator EPA-74, and the pulse width is about 40 ns. The focus magnetic field is about 1 Tesla, generated by an RLC circuit. The width of discharge is about 15 ms. At the first step, with the input RF of 500 W level, more than 1 MW radiation is detected. The authors have found that the RF breakdown was the biggest problem to overcome. The problem came from both the output cavity and the vacuum (the vacuum pressure near the output cavity was about /spl sim/5/spl times/10/sup -3/ Torr). Then, the authors developed a new output cavity with lower Q and improved the vacuum pressure near the output gap, and more than 10 MW radiation is detected with the input RF of /spl sim/kW level. The efficiency is about 10%, the gain is about 40 dB.