Cold test of π-TM610 mode double-gap coaxial cavity coupled to coaxial line

The frequencies and the Q_ext of the π-TM₆₁₀ mode and its adjacent modes of an X-band double-gap coaxial cavity coupled to a coaxial line are tested and the potential band of the output circuit of multi-beam klystron is discussed. The characteristic impedances along the six beam channels of the π-TM₆₁₀ mode double-gap coaxial cavity are tested by the conventional approximate method and the relative characteristic impedances along different beam channels are measured by a new method. Our experimental results show that the π-TM₆₁₀ mode double-gap coaxial cavity coupled to a coaxial line has more uniform axial electric fields in the interaction gaps of the six beam channels than the TM₃₁₀ mode single-gap coaxial cavity coupled to a rectangular. So the output circuit of multi-beam klystron will be more efficient and more stable.