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A design study of a permanent magnet quadrupole focused helix traveling-wave tube

Periodic permanent magnet quadrupole (PMQ) lattices have the potential to provide the strong focusing required to successfully transport higher current beams than conventional PPM lattices. We present a design example of a PMQ lattice optimized for a 16 kV, 0.81 A beam along with particle simulations using the electron transport code, MICHELLE 3D. We also present analyses of the interaction of the elliptical beam formed in the PMQ lattice with a helical traveling-wave circuit to provide insights into the advantages afforded by PMQ focusing.