This is the second of a two-volume set for advanced students in physical electronic, plasma, and radio physics, optical and electronic engineering, applied mechanics, and space technologies. It offers a hierarchical treatment of undulative electrodynamic systems and describes systems such as EH-accelerators, EH-formers, EH-coolers, the klystron, and multi-harmonic two-stream superheterodyne free electron lasers. Special attention is paid to phenomena such as explosive instability, phase and polarization discrimination, and nonlinear generation of electric and magnetic fields.