AbstractThe penetration of the dynamic ergodic divertor (DED) field into the plasma is described in the wave approximation over the projected frequency range, f≤10 kHz. Candidate waves are first described in the WKB sense, both cold-collisional and warm plasma approximations being employed. There follows an analysis in terms of the wave magnetic field which identifies the rotating DED field with the fast wave; a coupling calculation shows this wave to penetrate to the resonant surface as it would in vacuum, undiminished by the presence of plasma. Ideal MHD breaks down at the resonant surface, the resistive layer playing a dominant role.