The effects of two successive high voltage pulses on aquatic organisms

The effects of pulsed electric field on organisms have been studied in many laboratories. Single rectangular pulse has been often used in such biological experiments. Authors reported the biological effects of three different profiles of pulsed voltage at the previous Pulsed Power Conference. Next interests are to investigate biological effects of the second pulse following just after the first pulse. Two types of pulsed power generators are designed in order to study the effects of two successive voltage pulses on the organisms. One is a pulsed power system that is composed of two sets of pulse forming network (PFN) with a triggered spark gap (TSG). By adopting the optical connections in its triggering system and adjusting the gap separation of TSG carefully, each of PFNs is able to be operated independently, generating two successive pulses with the same polarity, several kilo volts output and a time separation of several tens of micro second. Another is a bi-polar generator with a scheme of half-bridge inverter circuit using power MOSFET as closing switch. This generator is able to output two pulses in short time, one is positive and another is negative, and its maximum amplitude is 500 V and time separation of two pulses can be adjustable. First experimental results using these generators show that the effects on aquatic organisms by two successive pulses with same polarity are more enhanced by decreasing the time interval between two pulses, on the other hand, two pulses with both polarities weaken its influences.