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PLASMA RESEARCH, project B7
Lightning bolt underwater
A plasma tears through the water within a few nanoseconds. It may possibly regenerate catalytic surfaces at the push of a button.
Electrochemical cells help recycle CO2. However, the catalytic surfaces get worn down in the process. Researchers at the Collaborative Research Centre 1316 “Transient atmospheric plasmas: from plasmas to liquids to solids” at Ruhr-Universität Bochum (RUB) are exploring how they might be regenerated at the push of a button using extreme plasmas in water. In a first, they deployed optical spectroscopy and modelling to analyse such underwater plasmas in detail, which exist only for a few nanoseconds, and to theoretically describe the conditions during plasma ignition. They published their report in the journal Plasma Sources Science and Technology on 4 June 2019.
A plasma tears through the water within a few nanoseconds. Following plasma ignition, there is a high negative pressure difference at the tip of the electrode, which results in ruptures forming in the liquid. Plasma then spreads across those ruptures.
Video: Experimentalphysik II
Plasmas are ionised gases: they are formed when a gas is energised that then contains free electrons. In nature, plasmas occur inside stars or take the shape of polar lights on Earth. In engineering, plasmas are utilised for example to generate light in fluorescent lamps, or to manufacture new materials in the field of microelectronics. “Typically, plasmas are generated in the gas phase, for example in the air or in noble gases,” explains Katharina Grosse from the Institute for Experimental Physics II at RUB.
Ruptures in the water
In the current study, the researchers have generated plasmas directly in a liquid. To this end, they applied a high voltage to a submerged hairline electrode for the range of several billionth seconds. Following plasma ignition, there is a high negative pressure difference at the tip of the electrode, which results in ruptures forming in the liquid. Plasma then spreads across those ruptures. “Plasma can be compared with a lightning bolt – only in this case it happens underwater,” says Katharina Grosse.
Hotter than the sun
Using fast optical spectroscopy in combination with a fluid dynamics model, the research team identified the variations of power, pressure, and temperature in these plasmas. “In the process, we observed that the consumption inside these plasmas briefly amounts to up to 100 kilowatt. This corresponds with the connected load of several single-family homes,” points out Professor Achim von Keudell from the Institute for Experimental Physics II. In addition, pressures exceeding several thousand bars are generated – corresponding with or even exceeding the pressure at the deepest part of the Pacific Ocean. Finally, there are short bursts of temperatures of several thousand degrees, which roughly equal and even surpass the surface temperature of the sun.
Water is broken down into its components
Such extreme conditions last only for a very short time. “Studies to date had primarily focused on underwater plasmas in the microsecond range,” explains Katharina Grosse. “In that space of time, water molecules have the chance to compensate for the pressure of the plasma.” The extreme plasmas that have been the subject of the current study feature much faster processes. The water can’t compensate for the pressure and the molecules are broken down into their components. “The oxygen that is thus released plays a vital role for catalytic surfaces in electrochemical cells,” explains Katharina Grosse. “By re-oxidating such surfaces, it helps them regenerate and take up their full catalytic activity again. Moreover, reagents dissolved in water can also be activated, thus facilitating catalysis processes.”
By Meike Drießen, Translated by Donata Zuber
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New funding - Ruhr Conference
Plasma research contributes to new Research Center “Future Energy Materials and Systems”
The state NRW will fund four research centers and one research college during the next years in the framework of the funding instrument "Ruhr Konferenz". One research center “Future energy materials and systems” will support the plasma science at RUB in the area of synthetic plasma chemistry. Plasma chemistry is a key subject in the CRC 1316 and will be strengthend by this measure in the upcoming years. (Image (c) hagenvontroja)
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Public Relations
Plasma Trial Day - What is plasma and where does it find application in technology & research?
Interested high school students are invited to participate in the Plasma Trial Day on Jan. 28, 2020 from 10 a.m. to 3 p.m. online. The chairs of the Ruhr-Universität Bochum will introduce themselves.
Technical plasmas find their application in many areas of everyday life and enable many achievements of our engineered world, such as in microelectronics, optics or mechanical engineering. But also in areas like air purification, sterilization and medicine plasmas can be used effectively in innovative concepts.
The fundamentals of technical applications are our field of research. We work interdisciplinary with partners from research and industry to develop innovative concepts and systems. And we would like to explain to you the largely unknown concept of physical plasma and introduce you to how we use and research the "fourth state of matter". Furthermore, we would like to show you how you might become part of a research team in the future!
Please register by email to:
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Project meeting 16./17.11.2020
Fall meeting of the consortium
The annual fall meeting of the CRC took place online to discuss the recent progress within the projects and their collaborations. Due to the online format it was easy to integrate the Mercator fellows into these discussions. The meeting was complemented by a small workshop on communication aspects related to gender issues.
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New appointment
Thomas Mussenbrock appointed at RUB
Since November 1, 2020, Prof. Dr. Thomas Mussenbrock has held the professorship for plasma technology at the Faculty of Electrical Engineering and Information Technology.
He conducts research on low temperature plasmas as well as on nanoelectronic and nanoionic components. His team develops analytical and numerical methods for modeling and simulation and applies them in interaction with experiments. "At the Ruhr-University Bochum, I find the ideal conditions for this," explains Thomas Mussenbrock. "Here, these experiments run right next door. I can follow them live and draw conclusions for our simulations, which in turn have a positive effect on the next experiments. In concrete terms, it is often a question of getting energy into a plasma efficiently and in a targeted manner. "Our goal is to excite only very specific particles." For Thomas Mussenbrock, much of his work revolves around the transport of energy and matter. "We want to understand the macroscopic behavior of the systems on the basis of the microscopic dynamics of the atoms, molecules, electrons and photons involved," the researcher explains.
In detail, plasmas play a decisive role in the manufacture of microelectronic components and circuits, for example. "More than 70 percent of all manufacturing steps are plasma-assisted," says Thomas Mussenbrock. "It is not for nothing that they say: No plasma, no iPad.
The chair of plasma technology is involved in two collaborative research centers among others. This research centers are the collaborative research center transregional SFB-TR 87 "Pulsed High-Power Plasmas for the Synthesis of Nanostructured Functional Layers," and the CRC 1316 "Transient Atmospheric Pressure Plasmas - from Plasma to Liquids to Solids,". Morevoer, Thomas Mussenbrock is also involved in the research group of the German Research Foundation FOR 2093 "Memristive Components for Neural Systems".
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New in the team
Judith Golda appointed as assistant professor for plasma physics at interfaces
The members of the plasma research groups on campus welcome its newest member Jun. Prof. Dr. Judith Golda, who will take over the group "Plasma Physics at Interfaces" from 01.11.2020. Dr. Golda studied and received her doctorate in Bochum.
After several stays abroad, she was last employed as group leader at the Christian-Albrechts-University of Kiel. In her research, she focuses on the investigation of non-equilibrium plasmas and their interaction with surrounding media such as solids or liquids by means of numerous spectroscopic techniques. These topics are seamlessly embedded in the current SFB 1316.
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Internationalization
Successful Plasma Summer School in 2020 in an online format
Due to the current situation, this year's summer school did not take place at the usual location of the physics center in Bad Honnef, but online. The regular programme consisting of basic plasma physics lectures combined with a master class on special topics could not take place as usual. Nevertheless, all teachers have agreed to deliver their basic lectures via an online video format. The summer school was extended to two weeks with two lectures per day. This year more people were able to tune in, because the online format is much easier to reach from regions with limited travel possibilities.
The lectures were technically flawless and the feedback from students and teachers was very positive. Many discussions and interactions could be made possible due to the high commitment of all teachers. Two practical workshops were also held by L. L. Alves on solving the Boltzmann equation and by N. Braithwaite on analyzing the Paschen curve.
We hope for another summer school in 2021, then again in the facilities of the physics center in Bad Honnef. The latest information on the planning for 2021 will be published at the summer school homepage in March 2021.
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MGK activity
Great colloquium planned for April 2021
As MGK activity of the CRC 1316 for all PhD students as well as PostDocs of the collaborative research center, a colloquium taking place in a conference center is organized. The program is planned for two days in a conference center. The colloquium is in the frame of an informal format, so that intense discussion and questions can arise.
Associated PhD students or PostDocs from the SFB-TR 87 as well as collaborating institutes are welcome.
The colloquium is planned for 21/04/21 until 22/04/21 2021 in Maria in der Aue in Wermelskirchen.
Further information and the registration are realized via a separate page: MGK colloquium.
The organization is done by two Phd students from the CRC 1316, Jan Kuhfeld and Patrick Preissing. For questions, both can be contacted directly or via sfb1316(at)rub.de.
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Successful collaboration with INP Greifswald
Research data management as central aspect within the collaborative research centres
Research data is a central output of science. They expand the scientific knowledge and are the basis for future research projects. The documentation of research data should follow subject-specific standards. The long-term archiving of research data is important for the quality assurance of any scientific work, but is also a fundamental prerequisite to allow the reusability of research results.
Researcher from the INP Greifswald enrolled a BMBF funded project with the title Quality assurance and networking of research data in plasma technology - QPTDat. This project aims to develop and test processes and methods for a quality assured and interdisciplinary reuse of research data from plasma technology.
QPTDat cooperation
A collaboration between INP and the CRC 1316 started in 2018 and now the Research Department Plasmas with Complex Interactions, and also the SFB-TR 87 join the activities on research data management. A workshop organized by INP Greifswald in January 2020 was the starting point for further active implementations in the field of research data management in the plasma community in the CRCs as well as in the Research Department.
First measures at EP2
As a first measure, an initiative at the research group EP2 at RUB results in an improved data storage on the local server of the institute. The storage volume has a regular backup and granting access to the complete group or to individual persons is possible. Beside measurement data, all further analysis steps are documented including meta data from all process steps. The members of the research group used a file name scheme, so that files can be found easily by other researchers.
Research data repository
Finally, published research data can be stored and published for the open public on the repository at
The idea of such a repository is the full documentation of measurement conditions (measurement data in a readable file format including meta data). First research groups from the CRCs have access to this repository and upload research data of published papers.
The concept of the repository is based on a multi-level system for publishing records. Users can put data online for review, which are then published by group moderators. The standards for publishing records must be defined by the group. In addition, meta data standards are currently being developed within the CRCs and together with INP Greifswald, so that data entry will be clearer and more uniform in future.
NFDI4Phys
Recently, the Research Department Plasmas with Complex Interactions has started to join the collaboration of different scientific institutions within the so-called NFDI4Phys consortium. It aims to create structures and tools to simplify and unify the exchange of (mainly) numerical factual data in all areas of physics, with related disciplines and with the industry. The consortium is applying to the DFG for funding within the National Research Data Infrastructure (NFDI) project.
Within the framework of the NFDI4Phys consortium, the CRCs developing meta data standards for research questions in plasma science. Further goals are to contribute to the definition of basic and interdisciplinary standards and to develop methods to make research data from different sources generally accessible and interpretable.
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