Elastic vibrations and waves in a superconducting torus

Experiments on a small 16 coil superconducting torus, modeled after a tokamak fusion reactor design, demonstrate a number of dynamic phenomena resulting from mangetoelastic coupling in the torus. Almost all of the vibratory natural frequencies are observed to decrease with current, resulting in eventual buckling of one of the modes. Further,lateral bending wave propagation around the periodic structure was observed. The measured wave speed increases with current. The wave speeds are related theoretically to the group velocity derived from frequency dispersion relations. Induced vibrations in the toroidal field coils due to pulsed poloidal coils are also reported. Finally buckling induced quench in the superconducting coils show large dynamic overshoot and vibrations following the quench of the torus.