Recent discrete model for small-signal analysis of traveling-wave tubes
Résumé
The numerical simulations of the wave-particle interaction, as it occurs in particular in traveling wave tubes, require new tools especially to investigate near the band edges of those devices. We propose a new approach (not limited to traveling wave tubes) using field decomposition allowing an important reduction of degrees of freedom : the discrete model. To assess its validity, we compare it in small-signal regime with Pierce’s four-wave theory. For both models, we take the same simplified fluid model and we express the associated circuit- beam impedances. We show analytically and with a numerical example that the newly developed reduced model is very close to the Pierce model, especially where the latter is well-established. Small deviations do occur at the edges of the amplification band, where Pierce’s model is known to lose its accuracy while the reduced model offers a valid physical interpretation.
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