Some switching problems in thermonuclear research

The switching studies and development work in progress at Harwell form a service to a developing and changing research programme; their objective must therefore be to have available for use as required a range of switches with a wide and flexible field of application. The most typical switching problem in thermonuclear research is that of transferring a large amount of energy quickly from an energy store to an inductive load, and then maintain the load current at or near its peak value for a comparatively long period. The requirements of the simple LC circuit with `clamping¿ switch can be met by various combinations of spark gap, vacuum arc and mechanical making switches; some of these arrangements and their practical limitations are discussed. The use of inductive energy storage will require circuit-breakers, which may have to be of largebreaking capacity and designed for frequent operation; several alternative circuit arrangements for providing a current zero are possible.