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End date: 2024 × Start date: 2020 × DDC: 530 × Subject: plasma × WGL Institute: INP ×

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Now showing 1 - 3 of 3
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    Efficiency of plasma-processed air for biological decontamination of crop seeds on the premise of unimpaired seed germination
    (Hoboken, NJ : Wiley Interscience, 2021) Wannicke, Nicola; Wagner, Robert; Stachowiak, Joerg; Nishime, Thalita M.C.; Ehlbeck, Joerg; Weltmann, Klaus‐Dieter; Brust, Henrike
    In this study, the antimicrobial effect of plasma-processed air (PPA) generated by a microwave-induced nonthermal plasma was investigated for preharvest utilization using three crop species: Barley, rape, and lupine. Bacillus atrophaeus spores were chosen as a model, inoculated onto seeds, and subsequently treated with PPA at two different flow rates, different filling regimes, and gas exposure times. PPA treatment was efficient in reducing viable spores of B. atrophaeus, reaching sporicidal effects in all species at certain parameter combinations. Maximum germination of seeds was strongly reduced in barley and rape seeds at some parameter combination, whereas it had a modest effect on lupine seeds. Seed hydrophilicity was not altered. Overall, PPA investigated in this study proved suitable for preharvest applications.
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    Verified modeling of a low pressure hydrogen plasma generated by electron cyclotron resonance
    (Bristol : IOP Publ., 2022) Sigeneger, F.; Ellis, J.; Harhausen, J.; Lang, N.; van Helden, J.H.
    A self-consistent fluid model has been successfully developed and employed to model an electron cyclotron resonance driven hydrogen plasma at low pressure. This model has enabled key insights to be made on the mutual interaction of microwave propagation, power density, plasma generation, and species transport at conditions where the critical plasma density is exceeded. The model has been verified by two experimental methods. Good agreement with the ion current density and floating potential—as measured by a retarding energy field analyzer—and excellent agreement with the atomic hydrogen density—as measured by two-photon absorption laser induced fluorescence—enables a high level of confidence in the validity of the simulation.
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    Enhancing surface production of negative ions using nitrogen doped diamond in a deuterium plasma
    (Bristol : IOP Publ., 2020) Smith, Gregory J.; Ellis, James; Moussaoui, Roba; Pardanaud, Cédric; Martin, Céline; Achard, Jocelyn; Issaoui, Riadh; Gans, Timo; Dedrick, James P.; Cartry, Gilles
    The production of negative ions is of significant interest for applications including mass spectrometry, particle acceleration, material surface processing, and neutral beam injection for magnetic confinement fusion. Methods to improve the efficiency of the surface production of negative ions, without the use of low work function metals, are of interest for mitigating the complex engineering challenges these materials introduce. In this study we investigate the production of negative ions by doping diamond with nitrogen. Negatively biased (-20 V or-130 V), nitrogen doped micro-crystalline diamond films are introduced to a low pressure deuterium plasma (helicon source operated in capacitive mode, 2 Pa, 26 W) and negative ion energy distribution functions are measured via mass spectrometry with respect to the surface temperature (30 °C to 750 °C) and dopant concentration. The results suggest that nitrogen doping has little influence on the yield when the sample is biased at-130 V, but when a relatively small bias voltage of-20 V is applied the yield is increased by a factor of 2 above that of un-doped diamond when its temperature reaches 550 °C. The doping of diamond with nitrogen is a new method for controlling the surface production of negative ions, which continues to be of significant interest for a wide variety of practical applications. © 2020 The Author(s). Published by IOP Publishing Ltd.