Development of a RF burst pulse generator using a non-linear transmission line for cancer treatment

Nanosecond and sub-nanosecond high voltage pulses can provide new applications. A cancer treatment by an ultra-short pulse high electric field is one of them. High power pulse electromagnetic wave has been proposed to apply the high electric field for that treatment. This work focuses on the design of a compact high power burst pulse electromagnetic wave generator using a nanosecond pulsed power generator for the cancer treatment. In previous study, we have used a LC inversion circuit as a power supply of the pulse electromagnetic wave generator. The LC inversion circuit is useful in order to output efficiently electromagnetic wave by the antenna. However, since the LC inversion circuit outputs the voltage waveform with damping oscillation, the duration of the burst pulse is under 100ns. Therefore, we focus on a coaxial nonlinear transmission line (NLTL) filled with ferrite cores. NLTL is capable of generating the high frequency osculation pulse wave. The non-linear coaxial line has the advantage of simple structure and low cost in comparison with the other NLTL using a non-linear element. Therefore we have investigated the burst pulse generator using the ferrite-filled coaxial non-linear transmission line in order to extend the duration of the burst oscillation for the cancer treatment. In the experiment, the pulse duration time and frequency of the output pulse of the NLTL for various conditions of the input pulse shape and the magnetic cores were investigated.