Mechanisms for energetic ion generation that could explain the observe
d ion energies in the anode plasma of a magnetically insulated ion dio
de [Phys. Rev. A 39, 5842 (1989)], are discussed. It is suggested that
strong electric fields that result from large density gradients on fe
w tens of micrometers near the anode cause the ion acceleration. Stead
y state as well as time-dependent accelerations are examined.