the interaction circuit being a helix or a helix-derived slow-wave structure (H01J23/44 - H01J23/48 take precedence)

Full Title

Details of transit-time tubes of the types covered by group H01J25/00 > Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy > to or from the interaction circuit > the interaction circuit being a helix or a helix-derived slow-wave structure (H01J23/44 - H01J23/48 take precedence)