Effects of a gyromagnetic material in a double-coupled helix traveling-wave tube

An analysis of the double-coupled helix with a gyromagnetic material (ferrite) inside the inner helix is presented using the field theory approach. Quantitative results are presented for the slow-wave solution. Qualitative results in the form of graphs illustrate wave propagation characteristics, impedance, resonance effects, and electric field variations for typical values of the ferrite parameters. The nonreciprocal nature of the ferrite material is demonstrated. Also, some important aspects of ferrite are pointed out which give support to the view that this type of material may improve traveling-wave tube operation.