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Summary
Dispersion of the slow-wave circuit, and synchronism condition for backward wave interaction: (a) forward fundamental (n=0), synchronism is at point B, intersection of the n=-1 space harmonic with the line of slope ve (the beam velocity), and (b) backward (n=0) fundamental.
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Dispersion of the slow-wave circuit, and synchronism condition for backward wave interaction: (a) forward fundamental (n=0), synchronism is at point B, intersection of the n=-1 space harmonic with the line of slope ve (the beam velocity), and (b) backward