Magnetic pulse welding provides high quality joining of fuel pin cladding for fast nuclear
reactors. The tool coil there operates under the most stressful conditions: 40 T magnetic
fields with tens of microseconds duration. This requires minimal coil inductance and
affects the capabilities and lifetime of the coils. Two approaches are being practiced to
enhance the coil durability: material research and construction optimization. The first
approach considers the use of high strength steels or composite materials for the coil
working area. The present work is aimed to realize the second approach – the use of multi position coils in order to maximize the number of parts welded in one coil.
Experiments and finite element modeling were carried out for two designs of two- and
four-position single-turn coils, which were made to process several workpieces in one
current pulse. The main parameters measured and calculated were the magnetic field
between the coil and the workpiece, and the ratio of its amplitude to the discharge current,
Bm/Im. The currents flowing through the coils were about 700 kA, which correspond to the
magnetic fields of 40–45 T. The FEM modeling revealed a 17–19% drop of the magnetic
induction near the insulated slit, which, however, did not prevent the helium-tight joining
of the tubes to the end plugs
