Then plasma formed in a fast B/sub z/ compression develops an instability after about a 4 to 5 mu sec quiescent period. Then consequence of the instability is that the plasma fissions into two well defined filaments that rotate with an angular velocity OMEGA approximates 10/sup 7/ sec/sup -1/. This configuration was was observed for many rotational periods. The plasma appears to remain confined, although impurity radiation indicates that some plasma reaches the walls during the fission process. The fission process in a deuterium plasma is accompanied by a rapid decline in neutron production. The origin of the rotation and the development of the instability are discussed. (auth)