The DC Pumped Quadrupole Amplifier- A Wave Analysis

Gordon, Buchsbaum, and Feinstein have proposed a new quasi-parametric electron-beam amplifier which uses the same transverse cyclotron waves as the Adler-Wade quadrupole parametric amplifier, but which is pumped with dc voltage applied via a twisted or staggered quadrupole structure. This paper analyses the dc pumped twisted-quadrupole case in terms of the four transverse beam waves and their coupling. Amplification is found to result from the coupling of the slow and fast cyclotron waves. The pump voltage does not actually pump, i.e., does not supply energy. An alternative dc pumping schemie is also examined and found to give coupling of the waves but no amplification.