Dynamic analysis of the propagation velocity of the LHD helical coil

One-side propagation of a normal-zone is observed in helical coils of the Large Helical Device and their model coil. At the current close to the minimum propagating current, a normal-zone propagates to only the downstream side of the current. At the higher currents, a normal-zone propagates to both sides with the slow upstream velocity that is almost half as downstream. This asymmetry should be caused by the electromagnetic interaction between the transfer current and the external magnetic field. Dynamic heat analyses with a finite differential method have been carried out to evaluate the amount of asymmetric heat generation. (author)