Experimental and numerical investigation of the armature/stator contact in magnetic flux compression generators

The ability of MFCGs for creating large current pulses is well accepted among the scientific community; however, little is understood regarding the fundamental mechanical and electrical mechanisms, and their interrelationship, governing the operation and efficiency of MFCGs. The main objective of this research was to conduct a series of experimental and numerical studies in an attempt to gain insight into the inner working of MFCGs. As a first step, the expansion characteristic of the exploding armature was selected as one of the major factors affecting the efficiency of MFCGs. Both numerical as well as experimental techniques were employed to capture the explosive-driven expansion behaviour of the armature. Numerical results were verified experimentally to determine the expansion-time history, expansion angle, expansion velocity, armature/stator contact velocity and the severity of the end-effect in a typical MFCG. The experimental and numerical results showed excellent agreement paving the way for future simulations using the established FE model. The results indicate that the radial and axial impact velocities between the armature and the stator are almost constant throughout the operation of MFCG. Moreover, the results indicate that the contact velocity between the armature decreases as the post-detonation time increases, reaching a constant value equal to the detonation velocity.