Fundamental Limitations and Topological Considerations for Fast Discharge Homopolar Machines

Fusion research experiments require high energy short duration pulses. A homopolar machine, as an inertial energy storage system, offers an attractive source of energy meeting these requirements. The Energy Storage Group at The University of Texas at Austin has investigated the fundamental limitations to the discharge time of homopolar machines of various topological configurations. This paper presents a mathematical model for fast discharge homopolar machines. Based on this model, various machine configurations are analyzed. A new configuration - the spool type machine - is also discussed, criteria for the evaluation of different alternatives are presented, and it is concluded that highly efficient (¿ 95%), high energy (¿ gigajoules), fast-discharge (¿ 5 to 30 milliseconds) homopolar inertial energy storage systems are technically feasible. Brief reference is also made to some of the experimental results obtained from the existing laboratory models.