Dynamics of the Voltage Distribution Over Cascaded Diodes

One state-of-the-art technology for high voltage (HV) generators consists of an LCC circuit with a symmetrical Cock-croft Walton (CW) voltage multiplier. A critical component of this design is a cascade of diodes connected in series that have to block a HV in reverse direction. It is a challenging task to obtain a sufficiently symmetric voltage drop over the diodes, which is influenced by parasitic capacitances, volatility of the reverse leakage currents, break through voltages, and recovery times from avalanching, as well as varying cooling conditions. An asymmetric voltage distribution can cause irreversible damage of individual diodes. Here, we present a detailed analysis of the dynamics of the voltage distribution over cascaded diodes and its technical implications. Hence, a model for the dynamic stress cascaded diodes are exposed to is presented in order to derive simulation methods that allow for an accurate prediction of the diodes' stress and, moreover, for designing frameworks for a stable long-term operation of cascaded diodes.