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Author: Brandenburg, Ronny × Has files: Yes × Version: publishedVersion × Publisher: Bristol : IOP Publ. × WGL Institute: INP ×

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    Electric field determination in transient plasmas: in situ & non-invasive methods
    (Bristol : IOP Publ., 2022) Goldberg, Benjamin M.; Hoder, Tomáš; Brandenburg, Ronny
    One of the primary basic plasma parameters within transient nonequilibrium plasmas is the reduced electric field strength, roughly understood as the ratio of the electrical energy given to the charged species between two collisions. While physical probes have historically been used for electric field measurements, recent advances in high intensity lasers and sensitive detection methods have allowed for non-invasive optical electric field determination in nearly any discharge configuration with time-resolution up to the sub-nanosecond range and sub-millimeter spatial resolution. This topical review serves to highlight several non-invasive methods for in situ electric field strength determination in transient plasmas ranging from high vacuum environments to atmospheric pressure and above. We will discuss the advantages and proper implementation of (i) laser induced fluorescence dip spectroscopy for measurements in low pressure RF discharges, (ii) optical emission spectroscopy based methods for nitrogen, helium or hydrogen containing discharges, (iii) electric field induced coherent Raman scattering, and (iv) electric field induced second harmonic generation. The physical mechanism for each method will be described as well as basic implementation and highlighting recent results.
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    Corrigendum: Dielectric barrier discharges: progress on plasma sources and on the understanding of regimes and single filaments (Plasma Sources Science and Technology (2017) 26 (053001) DOI: 10.1088/1361-6595/aa6426)
    (Bristol : IOP Publ., 2018) Brandenburg, Ronny
    The paper Dielectric barrier discharges: progress on plasma sources and on the understanding of regimes and single filaments? [1] contains a serious misprint in the section ?Electrical behavior and characterization?. The correct equation (5) for the determination of the gap voltage Ug is as follows (Formula Presented). The second term is the voltage across the barrier (Ub) which is determined by the charge Q t and the capacity of the barrier(s) Cd. The parameter 1 Ccell as written in the original paper is not correct, and a misprint. The sum of gap voltage and barrier voltage equals the applied voltage V t . Detailed explanations about the formula can be found in the cited literature, in particular [2-4].
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    Dielectric barrier discharges: progress on plasma sources and on the understanding of regimes and single filaments
    (Bristol : IOP Publ., 2017-3-30) Brandenburg, Ronny
    Dielectric barrier discharges (DBDs) are plasmas generated in configurations with an insulating (dielectric) material between the electrodes which is responsible for a self-pulsing operation. DBDs are a typical example of nonthermal atmospheric or normal pressure gas discharges. Initially used for the generation of ozone, they have opened up many other fields of application. Therefore DBDs are a relevant tool in current plasma technology as well as an object for fundamental studies. Another motivation for further research is the fact that so-called partial discharges in insulated high voltage systems are special types of DBDs. The breakdown processes, the formation of structures, and the role of surface processes are currently under investigation. This review is intended to give an update to the already existing literature on DBDs considering the research and development within the last two decades. The main principles and different modes of discharge generation are summarized. A collection of known as well as special electrode configurations and reactor designs will be presented. This shall demonstrate the different and broad possibilities, but also the similarities and common aspects of devices for different fields of applications explored within the last years. The main part is devoted to the progress on the investigation of different aspects of breakdown and plasma formation with the focus on single filaments or microdischarges. This includes a summary of the current knowledge on the electrical characterization of filamentary DBDs. In particular, the recent new insights on the elementary volume and surface memory mechanisms in these discharges will be discussed. An outlook for the forthcoming challenges on research and development will be given.