Limitations of NOx removal by pulsed corona reactors

No abstract

Matching a nanosecond pulse source to a CO2 plasma load

This paper presents the investigation of the efficiency\u3cbr/\u3eof energy transfer, or matching, between a nanosecond pulse\u3cbr/\u3esource and a corona plasma reactor flushed with CO2. In order\u3cbr/\u3eto optimize this matching, the effects of multiple parameters are\u3cbr/\u3einvestigated, such as pulse duration and amplitude, and reactor\u3cbr/\u3elength, as well as various inner electrodes. We conclude that,\u3cbr/\u3ewithin the range of parameters investigated, matching increases\u3cbr/\u3ewith pulse length and duration, as well as with reactor length.\u3cbr/\u3eFurthermore, the use of multiple inner electrodes resulted in\u3cbr/\u3ematching of over 90 percent

Experimental setup for temporally and spatially resolved ICCD imaging of (sub)nanosecond streamer plasma

Streamer discharges are efficient non-thermal plasmas for air purification and can be generated in wire-cylinder electrode structures (the plasma reactor). When (sub)nanosecond high-voltage pulses are used to generate the plasma, components like a plasma reactor behave as transmission lines, where transmission times and reflections become important. We want to visually study the influence of these transmission-line effects on the streamer development in the reactor. Therefore, we need a unique experimental setup, which allows us to image the streamers with nanosecond time resolution over the entire length of the plasma reactor. This paper describes the setup we developed for this purpose. The setup consists of a large frame in which a specially designed plasma reactor can be mounted and imaged from below by an intensified charge-coupled device (ICCD) camera. This camera is mounted on a platform which can be moved by a stepper motor. A computer automates all the experiments and controls the camera movement, camera settings, and the nanosecond high-voltage pulse source we use for the experiments. With the automated setup, we can make ICCD images of the entire plasma reactor at different instances of time with nanosecond resolution (with a jitter of less than several hundreds of picoseconds). Consequently, parameters such as the streamer length and width can be calculated automatically

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

Matching a nanosecond pulse generator to a corona plasma reactor

abstract onl

Raether-Meek criterion for prediction of electrodeless discharge inception on a dielectric surface in different gases

\u3cp\u3eElectrodeless streamer inception on an epoxy surface under AC voltage stress was investigated for different gas compositions and pressures, with a focus on the pressure region below 1 bar. For this purpose, we used a set-up with cylindrical electrodes embedded out-of-axis in a cylindrical epoxy rod. Experiments were performed in N\u3csub\u3e2\u3c/sub\u3e, SF\u3csub\u3e6\u3c/sub\u3e, ambient air, Ar and CO\u3csub\u3e2\u3c/sub\u3e. The discharge inception voltage was measured, from which the critical value K of the ionization integral was reconstructed assuming a non-disturbed Laplacian field distribution. We have validated that for electropositive gases Ar an N\u3csub\u3e2\u3c/sub\u3e the generally assumed value of K = 10 is in good agreement with our measurements. For electronegative gases, however, the experimentally obtained values turned out to be considerably higher. We attribute this discrepancy mainly to the statistical time delay of the first electron; to increase the probability of discharge inception in a critical region, it was necessary to extend the critical area by means of applying an overvoltage to the system.\u3c/p\u3

Considerations in designing and testing plasma devices for medical applications

Cold atmospheric plasma has been shown to have great potential for many applications on or in the human body, such as disinfection, wound healing, and cancer treatment. Several medical plasma devices have been developed and have obtained CE certification. However, the route there and into clinical practice is not straightforward. Already during the design stage, many matters need to be taken into account: (1) application and user requirements, (2) medical device regulations, e.g. on electrical safety and electromagnetic compatibility, and (3) production-related issues. Subsequent research should be conducted using a setup that resembles the clinical situation as closely as possible, since seemingly insignificant factors can have a large influence on the plasma and its effects. To ensure that the CE marked device will actually be adopted in clinical practice requires further actions during the research and development process: the demands and concerns of all parties directly and indirectly involved in its use should be identified and at least the crucial parties should be acquainted with plasma medicine and the specific medical device. Some examples will be given from the R&D process of a new flexible volume Dielectric Barrier Discharge (vDBD)