F.J.C.M. Beckers

Supercritical fluids for high-power switching

Fast and repetitive switching in high-power circuits is a challenging task where the ultimate solutions still have to be found. Areas of application are pulsed power technology and power stations. We proposed a new approach. Supercritical fluids have insulation strength and thermal properties like liquids and fluidity, self-healing and absence of bubbles like gases. Thats why we start investigating the subject of plasma switches in supercritical media. First results indicate excellent switch recovery and high insulation strength.

Applications of repetitive pulsed power, research at TU/E

Summary form only given. Current pulsed plasma research at TU/e Eindhoven, Department of Electrical Engineering, focuses on the integration of pulsed power technology into processes of multidisciplinary character. Examples of such processes are sustainable energy generation, chemical processing, and plasmas in super critical media. The research area concerns three interrelated systems: power modulator (1), interfacing plasma (2) and target process (3). The main challenges are adequate energy transfer between the three systems, tuning of the plasma energy levels and durable fast switching systems. The results show that pulsed power is a reliable and controllable technology for reducing industrial emissions, for syngas conditioning and for unconventional chemical processing. Our research will shift more in the direction of pulsed power produced plasmas for sustainable technology. Plasmas, chaotic in nature and present everywhere in the universe can be tailor made in the laboratory. Such controlled pulsed plasmas create intelligent processing to facilitate the drive towards sustainability. To proceed along these lines the research has to focus on the generation of pre-defined plasmas and selective processing. Consequently, our efforts are be directed to integrating the three competence areas of plasma physics, pulsed power technology and chemical process technology. Recent results of the work will be summarized. Items will include radical efficiency of streamer phases, non-steady state chemistry, tar removal from biomass derived syngas, industrial systems for VOC reduction and plasmas under supercritical conditions.

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.

Proposing supercritical fluids as a replacement for SF 6 in high-voltage power switches: Gas discharges in supercritical fluids for make and break operation

Gas discharges in supercritical fluids are an excellent candidate for high-power switching duty. Experimental and theoretical research has been performed. We present an analysis of results and a quick comparison with SF6 and CO2.

Pulsed power applications research: From super critical switches to renewable fuels

Important aspects of pulsed power processing that up to now received little attention are opened and summarized. A start is made in dealing with these aspects. They can be summarized as matching power source to process by controlling the global parameters impedance, time distribution, energy distribution and spatial distribution. An application is presented that can help changing the future of the energy policy: direct conversion of renewable power into fuels.

Evaluation of a solid state 120 kV microsecond pulse charger for a 1–10 nanosecond pulse generator

Summary form only given. In this paper we present a solid state 120 kV microsecond pulse charger for our nanosecond pulse generator [1]. The pulse forming line of our nanosecond pulse generator must be charged with microsecond pulses to prevent pre-firing of its oil spark-gap. The pulse charger consists of three identical very compact pulse transformer units with integrated electronics. The electronics are mounted on a compact PCB and consist mainly of a number of parallel connected IGBTs that switch a primary capacitor bank into the pulse transformer. Each pulse charger unit can generate 50 kV microsecond pulses into a 350 pF load at 1 kHz repetition rate. Connected together they are able to deliver more than 120 kV into a 100 pF load. This 100 pF load is the pulse forming line of our nanosecond pulse generator at its maximum length of 1 m. The pulse charger is able to operate in an EMI unfriendly environment due to its compact lay-out and optical triggering of the IGBTs.

A Linear-Transformer-Driver (LTD) with multiple self-triggered switches

Multiple switches are normally required for the generation of very high pulse power levels. The critical problem related to multiple switches is how to synchronize them in a short time interval and how to obtain current/voltage balance. A multiple-switch technique based on a TLT (Transmission-Line-Transformer) can solve this problem. It provides a failure-free solution to synchronize multiple switches automatically like in a Marx generator. In contrast to the Marx generator, it can produce pulses with various voltage and current gains and with a high degree of freedom in choosing output impedances. This technology has been investigated systematically. The feasibility of the technology has been demonstrated with a ten-switch (spark gaps) prototype. Pulses with a rise-time of 10 ns, a pulse width of 55 ns, a peak output power of 300–810 MW, a peak output voltage of 40–77 kV, and a peak output current of 6–11 kA have been achieved at a repetition rate of 300 pps and with an energy efficiency of over 93%. Also solid-state switches can be applied in this topology, e.g. proper operation of multiple thyristors has been verified for current multiplication. Moreover, the application of this topology for other circuits, such as Blumlein, Inductive-Voltage-Adder, Linear-Transformer-Driver, was explored.