Output Characteristics of Bipolar Pulse From High-Frequency Burst Pulse Generator Constructed by Nonlinear LC Ladders Using Magnetic Switches

摘要

We have designed a compact, high-power, pulsed electromagnetic wave generator outputting frequencies of several tens of MHz. The generator is intended for bioelectrics via a nanosecond-pulsed high electric field. Ideally, the burst pulse should comprise multiple oscillations at a single frequency. For this purpose, our pulse generator continuously outputs multiple pulses via a nonlinear transmission line (NLTL) using magnetic switches. However, as the pulses in the pulse train are unipolar, they collectively generate a low-frequency component which is superimposed on the target frequency of the burst pulse. To avoid this problem, we developed a circuit that generates a bipolar burst pulse with a single-frequency component. To generate a bipolar pulse, two NLTLs generating a unipolar pulse were connected parallel to the load through a discharge gap switch, and were synchronized by three electrodes. The gap switch contains two internal gaps that discharge with the same timing, ensured by a light trigger that emits discharge light to the other gap. The two NLTLs are charged with opposite polarity. This generator outputs bipolar burst pulses of 3 kV and 19 MHz with a probability of 95% or higher. In addition, the device was designed to withstand gap-length variations of the two gap switches.