A small size 7 Tesla flux-concentrator of modular construction fed by a small thyristor pulse generator

The generation of high magnetic pulsed fields in circularly cylindrical volumes of short length with a conventional Bitter coil design leads to difficult technical problems. We will show that in these cases a special design of a flux concentrator may be an alternative solution. The existing flux concentrator systems are composed of a cylindrical conducting core (with inner bore and radial slot) as single turn secondary coil, surrounded by an exciting multi-turn primary coil. Applying a pulsed voltage to the primary the induced current - due to the slot - will be urged to flow around the inner bore in a thin layer (skin-effect). Since on the outer periphery exciting and induced current have opposite directions nearly the total flux will be concentrated in the inner bore. Obviously the efficiency of current transfer from primary to core depends on coupling. Therefore a multilayer primary coil is an improper means of raising the total excitation. However the modular construction proposed here allows the total excitation to be increased with maintaining the efficiency by interlacing further secondary and primary coils. Together with a small thyristor pulse generator we thus arrive at a small size simple and inexpensive high field system which may easily be adapted to various needs in laboratory and instrumentation applications.