Flux Concentrator for High-Intensity Pulsed Magnetic Fields

Use of multiturn coil structure in the production of several hundred kilogauss pulsed fields is discussed with specific emphasis on coil life. The magnetic force that shortens the coil life is reduced by introducing a flux concentration device. Into the multiturn coil is inserted a rigid, slotted metal slug that generates induction current in such a way as to shift the magnetic flux from the multiturn to the central vacuum region and serves as a flux concentrator. Electromagnetically and mechanically this scheme is a convenient synthesis of the multiturn and single turn coils. The advantage of this scheme is most apparent for tape-wound coil structures, and a quantitative analysis of the flux pattern relevant to this coil system is given. An analog computer is employed in solving the time dependence of the field. The results are documented by experimental tests carried out with a 3000-μf, 4-kv capacitor bank.