Pulsed DC acceleration

Change of title : Pulsed DC electron acceleration for the generation of ultra-short relativistic electron bunches. No abstract

Photoconductive switching of an air-filled high-voltage spark gap : Pushing the limits of spark gap switching

In this contribution we present the recent results on photoconductive spark gap switching. This new way of switching combines the benefits of both laser-triggered spark gap switches and photoconductive semiconductor switches. High voltages can now be switched with rise times of the order ps and almost no time jitter. We will also show that for this new way of switching, conventional theory is no longer sufficient to describe the switching behavior. A new approach of theoretical spark gap optimization is required to push the limits further

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 TLT's have an input impedance of 3.125 O. Their output impedances are 50 and 200 O, 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

The Eindhoven high-brightness electron program

No abstract

Design of a nanosecond high voltage surface discharge switch

In this paper, we propose a concept for a novel high voltage low impedance surface discharge switch. The mechanism of surface discharges in gas was investigated on the nanosecond scale by Mesyats (2005). The important parameters which determine the switching performance of a pulsed-charged surface discharge switch, namely breakdown voltage, breakdown jitter and multi-channelling behaviour are controlled by dimensions of the discharge gap, the characteristics of the dielectric, the type and pressure of the gas and the rise time of the applied voltage pulse. The number of channels formed in a surface discharge switch is mainly a function of the applied voltage pulse (dV/dt > 1 kV/ns)2. The breakdown mechanism of a surface discharge switch was investigated by Reinovsky and Goforth (2004). A novel design of high voltage low impedance surface discharge switch was simulated in CST Microwave Studio. The basic design parameters were 2 nanosecond pulse length, very low characteristics impedance (2 Omega) and 1 nanosecond rise time. A high dielectric constant causes a low impedance, while keeping the distance between the powered electrode and the grounded base plate large enough to prevent breakdown. Th

Design of a nanosecond high voltage multiple-stage spark gap switch

Summary form only given. Spark-gap switches are currently extensively used in pulse power systems. High power pulsed applications, however, require fast rise time and low inductance of the switch. The advantage of using a multiple gap switch (several spark gaps in series) is its sharpening effect. If the first gap breaks down, an over-voltage will occur over the remaining ones, resulting in successive breakdowns of the other gaps. The last one determines the instance of the switching. By optimizing the number of gaps and using gas at high pressure, multiple-gap switch/switches can be used for repetitive application. Fast rise times (down to 1 nanosecond) are obtainable because of the short distance of the individual gaps