Energy storage for thermonuclear research

The basis of most British work on controlled fusion is the pinch effect, and the experiments are essentially pulse operated. Many other suggested thermonuclear devices are also pulse operated or use pulsed model experiments to limit the mean-power requirements. To operate such pulsed experiments, where energy is often required at very high levels, it is usual to `charge¿ a suitable energy store over a long period¿several seconds. This energy is then discharged into the experimental `load¿ in a period which may be a few microseconds or an appreciable fraction of a second. Energy may be stored as electric charge, magnetic flux, mechanical energy or chemical energy, and these various methods are considered. It is shown that storage as electric charge in a capacitor is most suitable where a rapid discharge is required. Magnetic storage as current in an inductance has its greatest usefulness where energy is required for periods of milliseconds, whilst machines and batteries are more appropriate to the longer pulses. For large-scale experiments the energy store can be a large fraction of the capital cost and an economic study of the various possibilities is important. It is suggested that a reasonable price for an energystorage system has been achieved when the capital cost is of the same order, or less, than the cost of the electrical energy to be passed through it in its designed life.