Electrical modeling of pulsed power systems for biomedical applications

High intensity (/spl sim/2.5 MV/m) short duration (ns & sub-ns) pulses can affect the intracellular structures without adversely affecting the outer cell membrane. An interesting effect of such pulses is apoptosis or programmed cell death. Generation of high voltage short duration pulses require fast switches and one or more pulse compression sections. Blumlein pulsed forming networks (PFN) are the most common circuit topology used for short pulse generation. The pulse shape and the rise/fall time of the pulse delivered to the load, depends on the response time of the switch and the characteristics of the Blumlein. Traditionally, the transmission line structures used in the Blumlein are modeled as ideal elements. At shorter pulse widths, the Blumlein models must account for the input and output edge effects, the distributed nature of the load, and the effects at Blumlein-load interface. A simple spice model is generated to simulate the edge effects of short Blumleins, and it is shown that the edge effects limits the achievable minimum pulse width and rise/fall times. Further improvements required in the spice model for shorter pulse lengths are also discussed.