 By this time, Soviet researchers had decided to build a larger toroidal machine along the lines suggested by Sakharov.In particular, their design considered one important point found in Kruskal's and Shafranov's works; if the helical path of the particles made them circulate around the plasma's circumference more rapidly than they circulated the long axis of the torus, the kink instability would be strongly suppressed.Today this basic concept is known as the "safety factor".