Abstract
In connection with the self-exciting dynamo problem, we study here time characteristics of magneto-hydrodynamical dynamos driven by fluid motions of magnitudes larger or smaller than those for stationary dynamos. For a given fluid velocity, there are infinite numbers of dynamos of different time characteristics. The fundamental dynamo (P1 solution in section 4) is developing or decaying according as the fluid velocity is larger or smaller than that for the stationary dynamo. There are also dynamos having quasi-periodical time characteristics. This periodical dynamo may be useful as a model for magnetic variable stars.
