a1 Institut für Theoretisehe Physik Ruhr-Universität Bochum, 4630 Bochum 1 Federal Republic of Germany
It is shown that a finite-amplitude ion-acoustic wave in a uniform magneto- plasma can enhance two-dimensional plasma vortices. The latter results from a modulational instability. The growth rates are obtained analytically.
(Received October 20 1980)