Spatially Asymmetric Distribution and Related Influence Factors of Injected Currents in Magnetically-Insulated Induction Voltage Adders

The special injection manner of magnetically-insulated induction voltage adders (MIVA) leads to the spatially asymmetric distributions of injected currents. It might affect the cavity performances and the characteristics of magnetic insulation in the secondary sides of MIVA, such as the electron sheath, flow impedance, and the current variations. In this paper, a full-size electromagnetic model of an induction cavity was developed, to acquire the spatial distribution of injected currents in the primary sides of cavities and the profiles of magnetic fields in the secondary sides. The dynamic process of the asymmetric coefficient, δ(t), was obtained. Some factors affecting the δ(t) were analyzed in detail, such as the pulse width of injected currents, the insulating medium in the primary sides of cavities, the number of injected pulses and their driver jitter. It is found that, the dynamic process of asymmetric coefficient, δ(t), consists of three phases, i.e., the fast drop process, steady state, and slow decrease process. The pulse width of injected currents affects the duration of the steady state and the subsequent third process. The insulating medium in the primary sides of cavities affects the spatial distributions of injected currents by changing the transmission speed of electrical pulses in cavities. The number of injected pulses has crucial influence on the current distributions. As the two pulses driving the same cavity could not arrive simultaneously, the current distributions would change. Moreover, the current injection experiments of a single-stage cavity in part confirm the simulation results.