On The Utilization Of Light Activated Junction Semiconductors As Saturable Capacitors, Theory And Application In Compression Lines

In a companion paper, we describe theory and experiments with reverse-biased light activated junction semiconductors and discuss their characteristics and capabilities as opening switches. In this paper we discuss the circuit properties of these devices and describe their behavior as saturable capacitors whose characteristic amp-second product is tunable. The complementarity of saturable capacitors to saturable inductors (volt-second devices) allows for unique nonlinear compression (electromagnetic shock) lines to be constructed by the judicious combination of both types of devices. The characteristics of this "doubly" nonlinear line are unique, with characteristics not realizable in transmission lines using either type alone. For instance the "doubly" nonlinear line operates at a constant average impedance, unlike e.g. saturable inductance lines where the impedance reduces with every stage. We shall discuss how the fundamental limits of the devices affect the parasitic inductances and capacitances and how they in turn affect the compression efficiency. Furthermore we describe an analytic treatment which establishes an optimum scenario for such compression lines where the influence of the switch characteristics and the number of stages influence the compression efficiency and overall efficiency.