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Baeva M.,Leibniz Institute for Plasma Science and Technology
Plasma Chemistry and Plasma Processing | Year: 2017

The paper gives an overview of the most common non-equilibrium approaches for modeling of tungsten-inert gas arc plasma, which have been developed up to date, in particular two-temperature and fully non-equilibrium approaches. The first group implies thermal non-equilibrium but chemical equilibrium whereas the second group describes the arc plasma avoiding assumptions of both thermal and chemical equilibrium. The common and specific features of the physical description are discussed. Results of the most recent fully non-equilibrium model, which is applied for the first time to tungsten-inert gas arc arrangement with a truncated conical tip of a doped tungsten cathode, are compared with those of previously published non-equilibrium models and experimental data. The general diffusion representation and more accurate boundary conditions incorporating the properties of the space-charge sheaths adjacent to the electrodes enable a novel description of the arc core, the near-electrode regions and the arc fringes in a self-consistent manner and provides a deeper insight into the arc properties. © 2017 Springer Science+Business Media New York


Von Woedtke T.,Leibniz Institute for Plasma Science and Technology | Metelmann H.-R.,University of Greifswald | Weltmann K.-D.,Leibniz Institute for Plasma Science and Technology
Contributions to Plasma Physics | Year: 2014

Driven by extensive basic research on plasma effects on living cells and microorganisms, plasma medicine has been developed as innovative medical research field during the last years. Besides partially established applications of plasma to treat materials or devices to allow effective medical applications with respect to biocompatibility or microbiological safety, respectively, the primary focus of plasma-medical research is the direct application of plasma as part of therapeutic concepts. Even if a huge number of atmospheric pressure plasma sources for biomedical applications are described in the literature and characterized by in vitro microbiology and cell biology, there is only a limited number of in vivo experience with animals or human beings up to now. Research in plasma medicine has been mainly focused on applications in dermatology and aesthetic surgery with the aim to support tissue regeneration to improve healing of infected and/or chronic wounds as well as to treat infective and inflamed skin diseases. In general, there are four cold atmospheric plasma sources which were tested comprehensively in animals as well as human beings with respect both to its therapeutic potential and the safety of its application. Three clinical trials with cold atmospheric pressure plasma sources have been carried out yet. All three studies realized in Germany are focused on ulcer treatment. Two cold atmospheric pressure plasma sources got a CE marking as medical device in 2013. This marks a very important step to bring plasma medicine into the clinical daily routine! In future, it will become a general practical requirement to adapt special plasma sources to specific medical applications. Consequently, it is one of the main requirements for the physical and technical field of research and development in plasma medicine to find solutions for modular and flexible plasma devices which are adaptive to some extent e.g. to variable target areas. Based on this as well as together with comprehensive basic research to get much more insight into detailed mechanisms of plasma-induced effects on living structures and the particular role of single plasma components, further fields of plasma application in vivo will be opened or extended, respectively, with both new targets like cancer treatment or new application sites like teeth, lung, eyes, nasal cavity or gastrointestinal tract. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Patent
Leibniz Institute for Plasma Science, Technology and Neoplas Gmbh | Date: 2015-06-05

The invention relates to a device, preferably a collar, for treating areas of human or animal skin or mucous membrane with a cold atmospheric pressure plasma by creating a dielectrically hindered surface discharge, comprising at least one flexible insulating material (1), a flexible high-voltage electrode (2), a flexible dielectric (3), a flexible grounded electrode (4) and a gas supply (7), characterized in that the flexible high-voltage electrode (2) is embedded in the insulating elastomer (3), having the effect of a dielectric, and the grounded electrode (4) is applied to the elastomer surface facing the surface to be treated.


Patent
NEOPLAS GmbH, Leibniz Institute for Plasma Science and Technology | Date: 2010-07-27

The invention relates to a device, preferably a collar, for treating areas of human or animal skin or mucous membrane with a cold atmospheric pressure plasma by creating a dielectrically hindered surface discharge, comprising at least one flexible insulating material (1), a flexible high-voltage electrode (2), a flexible dielectric (3), a flexible grounded electrode (4) and a gas supply (7), characterized in that the flexible high-voltage electrode (2) is embedded in the insulating elastomer (3), having the effect of a dielectric, and the grounded electrode (4) is applied to the elastomer surface facing the surface to be treated.


Hannemann M.,Leibniz Institute for Plasma Science and Technology
Contributions to Plasma Physics | Year: 2013

The energy distribution, the mean energy and the density of the electrons of low pressure plasmas may be obtained from the 2nd derivative of a Langmuir probe characteristic. Often numerical methods are used for differentiation. A simple numerical technique is the non-recursive digital or FIR filtering. Because of noise this process has to comprise also smoothing elements. The best way to achieve this is the successive use of a weakly smoothing interpolation based twofold differentiating filter and a strong smoothing filter. None of the usual smoothing filters exhibits all properties needed in the evaluation of probe characteristics. Window function based FIR filters represent a class of smoothing filters which is especially suited in this context because of its increasing stop band attenuation. A new smoothing filter based on a new parameterized window function is introduced. The testing of this new filter is performed and hints for finding of the filter parameters are given © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Weltmann K.-D.,Leibniz Institute for Plasma Science and Technology | Von Woedtke T.,Leibniz Institute for Plasma Science and Technology
IEEE Transactions on Plasma Science | Year: 2011

Plasma medicine is emerging worldwide, and some promising applications seem to be near the horizon. Direct therapeutic plasma application as the central field of plasma medicine will bring physical plasmas directly on or in a human (or animal) body. Campus PlasmaMed is a research association supported by the German Federal Ministry of Education and Research (BMBF), concentrated in the northeast of Germany and founded to explore promising and safe applications of atmospheric-pressure plasmas in medical therapy based on systematic and interdisciplinary basic research on the interactions of plasma components with living systems. Whereas a broad spectrum of plasma sources dedicated for biomedical applications has been reported during recent years, mainly two basic principles of plasma sources are used in the Campus PlasmaMed: atmospheric-pressure plasma jets and dielectric barrier discharges. A comprehensive assessment of potential risk factors, such as gas temperature, power transfer from plasma to the target, (V)UV radiation emission, or the generation of toxic gases and its release into the adjacencies, which could be dangerous for patients and therapists, has to be done as a basic precondition before any biomedical experiments can be started or a potential therapeutic application can be taken into consideration. Despite the fact that the initial plasma-source characterization and optimization are in the main responsibility of plasma physicists and engineers, potential users from the biomedical field should be integrated as soon as possible to include special needs and constraints for specific applications during early steps of development. This multidisciplinary research cooperation among plasma scientists and engineers on the one side and life scientists and clinicians on the other is one of the main characteristics of the Campus PlasmaMed. Such interdisciplinary cooperation is more than ever required for the characterization of biological effects of plasma sources, which has to be realized by a multistep program, starting with the investigations of plasma-liquid interactions and including a broad spectrum of in vitro tests with cells, as well as cell and tissue cultures up to isolated tissues or organs to be proved finally with animal experiments and clinical trials. Because there are no standardized criteria so far according to which atmospheric-pressure plasma sources can be assessed as to their suitability for medical applications, interdisciplinary results from plasma medical research have to be transferred into rules and standards to guarantee successful and safe practical application, including economic exploitation of plasma-medical research results. © 2011 IEEE.


Wendt M.,Leibniz Institute for Plasma Science and Technology
Journal of Physics D: Applied Physics | Year: 2011

The net emission coefficient of plasmas containing argon and iron at atmospheric pressure is calculated and analysed for the case of cylindrical geometry. Its values are obtained by integrating the monochromatic net emission coefficient taking into account continuous and line radiation. The width of the spectral lines is determined by Doppler broadening, natural, resonance, van der Waals, electron and ion Stark broadening. As Stark broadening is the most important broadening mechanism in the considered pressure and temperature range, the electron Stark widths are calculated following the semi-empirical Stark broadening theory. Additionally, the electron Stark widths of Ar, Ar +, Fe and Fe + are multiplied by scaling factors in order to reproduce experimental electron Stark widths. The scaling factor is determined for each species separately. For small plasma radii the net emission coefficient determined here shows good agreement with literature values where spherical geometry is considered while they decrease faster with increasing plasma radius. This behaviour is caused by the increase of the irradiation of the symmetry axis when cylindrical instead of spherical geometry is considered. For radii and temperatures typical of the metal filled core of arcs occurring in gas metal arc welding processes, i.e. radii between 1 and 2 × 10 -3 m and temperatures between 5000 and 10 000 K, the scaling of the Stark widths increases the net emission coefficient of iron plasmas by between 2% and 23%. In this parameter range the net emission coefficient of iron plasmas for cylindrical geometry is between 30% and 37% smaller than values calculated for spherical geometry. © 2011 IOP Publishing Ltd.


Patent
Leibniz Institute for Plasma Science and Technology | Date: 2010-08-12

A method and device for treatment of living cells with cold atmospheric pressure plasma while simultaneously applying selective electroporation of the cells are provided. The method is useful for the local selective killing of cancer cells, improvement of wound treatment and sterilization or decontamination of objects.


Patent
Leibniz Institute for Plasma Science and Technology | Date: 2013-05-08

The invention relates to a device for the treatment of free-form areas and zones of human or animal skin areas or plant surfaces by means of cold atmospheric-pressure plasma. The core of the device is a specific, preferably gas-permeable, electrode arrangement for generating a dielectrically impeded surface discharge where the earthed electrode is composed of electrically conductive textile material and the high-voltage electrode consists of a thin wire or electrically conductive thread which is sheathed with an insulting layer which has to meet specific requirements. On the basis of the present invention, it is possible to generate, in the area of diseased skin parts of the human body, in direct proximity to the skin surface or to wounds, a flat plasma for the treatment of the diseased areas which is acceptable in respect of the stress on the skin caused by temperature and electric potentials. The advantage of the gas-permeable textile sheet-like structure consists especially in that the arrangement can be placed flexibly onto variously curved surfaces and, in addition, offers the possibility of a gas exchange with the environment and/or the targeted dosing of a specific process gas mixture across the textile material into the active plasma zone.


Patent
Leibniz Institute for Plasma Science and Technology | Date: 2011-05-09

The invention relates to a method and to a device for quickly decontaminating and sterilizing preferably thermolabile goods using a plasma gas that is preferably generated from air as a process gas, with the subsequent humidification of said plasma gas with water. The method comprises the following steps: generating a plasma from air as the process gas, which forms reactive nitrogen and oxygen species; oxidizing NO to form NO_(2 )at temperatures below 400 C. so that a plasma-activated gas mixture forms having an NO_(2 )content of at least 0.3%; bringing said plasma-activated gas mixture in contact with water in one or more of the states of aggregation thereof; bringing the latter gas mixture in contact with the objects to be decontaminated or sterilized.

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