Operation efficiency of input switching device in megaampere class helical EMG

The initial magnetic field in a helical explosive magnetic generator (EMG) is formed by an external source. The magnetic flux capture in the helical EMG is realized by means of input switching device. Most often it is made in a form of radially positioned current conducting pin connected to a beginning of cylindrical helical coil [V.K. Chernyshev et al., 1997; V.K. Chernyshev et al., 2001]. At the moment of feed current maximum the helical EMG central armature closes to the pin. As a result, the initial magnetic flux is inside the helical coil. Herewith, most of the magnetic force lines are between the central armature and the helical coil loops. Since that moment the magnetic cumulation process starts [A.D. Sakharov et al., 1965]. This paper will present the experimental results characterizing fully the operation efficiency of the input switching device in the helical EMG. The obtained experimental data testify to the fact that the operation efficiency of the input switching device is different at different time moments. The most noticeable drop of the switching device operation efficiency occurs when the expanding central armature passes along the pin. The paper will describe the analysis results and will offer the conclusion about a reason of the input switching device operation efficiency drop. The approach will be proposed allowing the improvement of the helical EMG´ input switching device operation efficiency.