Sj Stefan Voeten

Design of a Subnanosecond Rise Time, Variable Pulse Duration, Variable Amplitude, Repetitive, High-Voltage Pulse Source

In this paper, we present a design approach of a single-line nanosecond pulse source by using a thorough analytical investigation and by verification with CST MICROWAVE STUDIO. Through detailed analysis and simulation, we arrive at a design for a fast rise time variable pulse duration pulse source which is able to produce 1-10 ns pulses with tens of kilovolt amplitude and less than hundreds of picoseconds rise time. This variable pulse duration is achieved by using telescopic antennas and ferrites in the pulse-forming line of the pulse source. Finally, we present a first implementation of a 5-ns pulse source with an oil spark gap for fast switching.

Parallel plate Transmission Line Transformer

A Transmission Line Transformer (TLT) can be used to transform high-voltage nanosecond pulses. These transformers rely on the fact that the length of the pulse is shorter than the transmission lines used. This allows connecting the transmission lines in parallel at the input and in series at the output. In the ideal case such structures achieve a voltage gain which equals the number of transmission lines used. To achieve maximum efficiency, mismatch and secondary modes must be suppressed. Here we describe a TLT based on parallel plate transmission lines. The chosen geometry results in a high efficiency, due to good matching and minimized secondary modes. A second advantage of this design is that the electric field strength between the conductors is the same throughout the entire TLT. This makes the design suitable for high voltage applications. To investigate the concept of this TLT design, measurements are done on two different TLT designs. One TLT consists of 4 transmission lines, while the other one has 8 lines. Both designs are constructed of DiBond™. This material consists of a flat polyethylene inner core with an aluminum sheet on both sides. Both TLTs have an input impedance of 3.125 Ω. Their output impedances are 50 and 200 Ω, respectively. The measurements show that, on a matched load, this structure achieves a voltage gain factor of 3.9 when using 4 transmission lines and 7.9 when using 8 lines.

Pulsed Power Technology

Pulsed power refers to the science and technology of accumulating energy over a relatively long period of time and releasing it as a high-power pulse composed of high voltage and current over a short period of time; as such, it has extremely high power but moderately low energy. Pulsed power is produced by transferring energy generally stored in capacitors and inductors to a load very quickly through switching devices. Applications of pulsed power continue expansion into fields including the environment, recycling, energy, defense, material processing, medical treatment, plasma medicine, and food and agriculture.

Optical Characterization of Surface Dielectric Barrier Discharges

Surface dielectric barrier discharges (SDBDs) provide homogeneous plasma over a large surface area. This allows surface treatments of foils, textiles, or fibers. In this paper, we present results of a study to characterize the pulsed performance of SDBD by fast imaging of the plasma development.