Generation and Switching of Magnetic Energies in the Megajoule Range by Explosive Systems

The results of an extensive experimental program on explosive-driven magnetic flux compression devices of the ``bellows'' type are described and discussed. These generators, in which explosively propelled conducting plates compress the magnetic flux into the final load, have been tested in single and multistage systems, generating axial fields of up to 700 kOe in volumes of the order of liters with a corresponding maximum magnetic energy in the load of 2 MJ. Bellows generators are best suited to match a single-turn solenoid as the inductive load and it is shown that in particular cases a combination of these generators with the recently described helical ones is of great interest. Particular attention is paid to a switching system (including a closing and opening switch) with which it is possible to transfer the magnetic energy accumulated in the generators into an appropriate inductive load within 10 μsec and less. A simple analysis and the experimental results show that this is feasible, although magnetic flux and energy losses are inevitable, particularly if high switch performances are required (e.g., opening time <5 μsec, initial current rise >1 MA/μsec).