Pulsed Electromagnetic Wave Generator Research Articles

Development of a High-Frequency Burst Pulse Generator for Cancer Cell Treatment and Comparison Between a High-Power Burst Pulse and a Single Pulse

Cancer treatment based on ultrashort pulses of strong electric fields has been developed as a novel biological application. This article focuses on the design of a compact high-power nanosecond pulsed electromagnetic wave generator for realizing cancer treatment via ultrashort pulsed electric fields. For this purpose, we developed a pulsed power generator that continuously outputs multiple pulses via a nonlinear transmission line (NLTL) using magnetic switches. The NLTL comprises a ladder of capacitors and saturable inductors and generates a pulse train by delaying the propagation of each pulse using the magnetic switch of each ladder. In this article, we achieved a higher output frequency compared to the previous generator. The frequency was increased from 13 to 150 MHz by employing a coaxial structure instead of discrete components. In addition, we demonstrate that the application of burst pulses to cancer cells is more effective than single pulses under the same conditions.

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

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.

Development of a High-Power Burst Pulse Generator Based on the Sequential Operation of Magnetic Switches

Nanosecond and subnanosecond high-voltage pulses have used in new biological applications, such as cancer treatment using an ultrashort pulsed high electric field. For this treatment, the use of high-power pulsed electromagnetic wave has been proposed to obtain the required high electric field. This paper focuses on the design of a compact high-power pulsed electromagnetic wave generator using a nanosecond pulsed power generator for cancer treatment. We developed a pulsed power generator that continuously outputs multiple pulses via a nonlinear transmission line (NLTL) using magnetic switches. The NLTL comprises a ladder of capacitors and saturable inductors. The NLTL generates a pulse train by delaying the propagation of the pulse using the magnetic switch of each ladder. The frequency of repetition of the burst pulse is 13.8 MHz. The peak output voltage is 7 kV at the maximum input voltage of 28 kV. The number of pulses in the pulse train can be varied by the number of units of the magnetic switch.

Development of a Cluster Burst Pulse Generator Based on a SOS Diode for Medical Applications

SUMMARYThis work focuses on the design of a compact high‐power pulsed electromagnetic wave generator using a nanosecond pulsed power generator for the cancer treatment. In the previous study, since the output voltage waveform of the pulsed power generator was damping oscillation, the duration of the burst pulse was under 100 ns. So the generator uses a magnetic switch instead of the gap switch and uses a SOS diode with current cutoff time of nanoseconds. The cluster pulse has six burst pulses that are repeated at 2 Mpps. The frequency of the burst pulse is 50 MHz. The peak output voltage is 7.5 kV.

SOSダイオードを用いた医療用クラスタバーストパルス発生装置の開発

This work focuses on the design of a compact high power pulsed electromagnetic wave generator using a nanosecond pulsed power generator for the cancer treatment. In previous study, since the output voltage waveform of the pulsed power generator was damping oscillation, the duration of the burst pulse was under 100 ns. So the generator uses a magnetic switch instead of the gap switch and uses a SOS diode with current cutoff time of nanoseconds. The cluster pulse has 6 burst pulses that are repeated at 2 Mpps. The frequency of the burst pulse is 50 MHz. The peak output voltage is 7.5 kV.

Intensity of electric field radiating from high-power pulsed electromagnetic wave generator for use in biological applications

Cancer treatment is one of several new applications which use nanosecond and subnanosecond high-voltage pulses. This study focuses on the design of a compact highpower pulsed electromagnetic wave generator using a nanosecond pulsed power generator to apply a high-intensity electric field for the treatment of cancer; the pulses cause apoptosis in cancer cells. We applied an L-C inversion circuit to the pulsed power generator to obtain a voltage waveform with a single frequency, which is applied to an antenna. A water gap switch and water capacitors were used in the L-C inversion circuit to obtain a pulsed voltage with a frequency element of 250 MHz. In this experiment, an electromagnetic wave was radiated underwater by a loop antenna. A measuring double loop antenna placed 0.15 m and 0.3 m from the radiating antenna detected electric field intensities of 112 kV/m and 49 kV/m, respectively. A focusing bowl was attached to the radiating antenna to obtain a higher electric field. The electric field intensity of the radiating antenna with the focusing bowl, 300 kV/m, was 6 times higher than that without the focusing bowl. The intensity distribution of the electric field focused by the focusing bowl was measured. A measuring small loop antenna detected peak electric field intensity of 11.3 kV/cm at a focal point. Areas with electric field intensity greater than 10.8 kV/cm were approximately 5 mm square and 3 mm wide in the x-z plane and y-axis, respectively.