Demonstration of a prototype high field, single-turn toroidal magnet system

Very high toroidal magnetic fields have been produced using a single-turn magnet powered by homopolar generators (HPGs). A design goal of 20 T confinement field has been met by the combination of a low-impedance toroidal magnet, a high-current, low-voltage power supply, and the use of a high-strength, high-conductivity copper alloy. The Ignition Technology Demonstration (ITD) is a 1/16 scale prototype of the proposed full-scale IGNITEX (Ignition Experiment) toroidal field (TF) magnet. Stresses and temperatures reached in the prototype TF magnet are representative of those that would be experienced in a 1.5-m major radius magnet with a 5-s flat top current profile. Synchronized, parallel operation of multiple HPGs into a single-turn toroidal magnet has been realized. The prototype TF magnet has produced toroidal magnetic fields up to 18.1 T on-axis with liquid nitrogen precooling and axial preloading of the magnet. Results of testing the prototype are presented in detail