Research interests
The focus of our group is on experimental plasma physics.
While the two-body problem can in general still be solved quite well analytically, the complexity is already increased considerably for only three bodies. In plasmas, however, particle densities on the order of 1015 to 1019 m-3 are generated, so these systems must be described using the methods of statistical physics. In addition, there are Coulomb forces acting on the charge, so plasmas exhibit collective behavior.
Plasmas play a major role in nature and technology. 99.9 % of the visible matter in the universe is in the plasma state. In contrast to astrophysical plasmas, all plasmas generated on Earth are in contact with surrounding media. The influence of such a medium fundamentally determines its properties, for example by the balance between particle generation and energy coupling in the plasma and losses at the surface. Conversely, the value of plasmas for technology even results directly from the influence of the plasma on the medium, e.g. more than 70 % of all process steps for the production of microelectronic components are based on plasma surface processes. Nevertheless, there are still major deficiencies in the description of non-equilibrium processes at this interface. Often the description is purely empirical and does not take into account the reciprocity of the processes at the corresponding interface between plasma and medium, for example when using secondary electron coefficients or sputtering rates. However, knowledge of these processes is essential for the further development of plasma technology, e.g. in the use of plasmas in catalysis for the production of CO2-neutral fuels.
In order to replace the empirical description with physical models, we design our plasma sources and our experiments specifically with this question in mind. For analysis, we use both plasma and surface diagnostics. We place great emphasis on supporting our complex experiments with simple model calculations and making the outcome of the experiments comparable to simulations.
Current research topics are charge effects of dielectrically barrier surface discharges, the interaction of plasmas and surfaces under the influence of laser radiation, and the use of plasmas in biocatalysis and medical applications.
- plasma interface
- atmospheric pressure plasma physics
- plasma chemistry in reactive plasmas
- reference sources and characterization measurements for plasma medicine
- plasma diagnostics:
- electrical power measurements
- (phase-resolved) optical emission spectroscopy
- ultraviolet spectroscopy
- laser absorption spectroscopy
Diagnostics and applications of plasma jets as CO source for sterilization in wound treatment
Funding source: DAAD
Projekt-ID: 57604427
Principal investigators: J. Golda, C. Douat, GREMI, Orléans
Funding period: 01/2022 - ongoing
Team
Description
Project-related person exchange program with France.
Pulsed plasma interaction with catalytic surfaces within micro-structured array devices
Funding source: DFG, (collaborative research centre) CRC 1316
Project number: A6
Principal investigators: J. Golda, M. Böke, V. Schulz-von der Gathen
Funding period: 01/2018 - ongoing
Team
Description
A metal-based microcavity array discharge enclosed by quartz dielectrics forms an in-plasma-catalyst reactor. These devices allow to integrate dielectric, catalytic surfaces as the cavity bottom. The plasma parameters as well as the distribution of the discharges inside and above the cavities are strongly dependent on external parameters such as cavity dimension, pressure and voltage. The project investigates the influence of the plasma conditions on the catalytic processes by observing the volume close to the catalyst following the gas flow. Especially the role of charged species is investigated by phase- and space-resolved diagnostics. Ex-situ measurements of the catalytic surfaces round off the experiments.
Self-organisation of sub-micrometer surface structures stimulated by microplasma generated reactive species and short-pulsed laser irradiation
Funding source: DFG, (collaborative research centre) CRC 1316
Project number: B2
Principal investigators: M. Böke, J. Golda, V. Schulz-von der Gathen
Funding period: 01/2018 - ongoing
Team
Description
The efficiency of catalysts is strongly dependent on their surface structures and its chemical state. This project is aiming at the plasma-laser induced modification and creation of microstructured, reactive surfaces that can be used in catalysis. Based on plasma-generated reactive species and the knowledge of generation and destruction mechanisms in the effluent, we tailor density distributions and fluxes of reactive species to surfaces, that are simultaneously (self-organised) structured by laser irradiation. Active and passive optical methods are applied to investigate the plasma kinetics and fluence of reactive species to surfaces. Ex-situ diagnostics complete the picture by investigation the surface properties down to the level of chemical states, its struture and catalytic performance.
Rational tuning of plasma and liquid chemistry for biocatalysis
Funding source: DFG, (collaborative research centre) CRC 1316
Project number: B11
Principal investigators: J. Bandow, J. Golda, A. Gibson
Funding period: 01/2022 - ongoing
Team
Description
Plasma-driven biocatalysis seeks to use plasma-produced reactive species, such as hydrogen peroxide, as reactants for the enzymatic conversion of substrates into valuable products. A key to achieving industrial use of this approach is to produce reactants in sufficient amounts and with high energy efficiency. The aim of this project is to develop a rational scheme for tuning the plasma-biocatalysis system by combining expertise and insight from experimental plasma and liquid diagnostics, numerical plasma and liquid chemistry simulations and biotechnology. In addition to characterising rates and mechanisms of hydrogen peroxide generation, the formation of unwanted plasma species that are toxic to enzymes will be monitored under different plasma operating conditions. On the basis of simulation and experiment, new strategies will be developed to increase the biocatalytic yield.
Diagnostics and applications of plasma jets as CO source for biomedical applications
Funding source: DAAD
Project ID: 57512561
Principal investigators: J. Golda, C. Douat, GREMI, Orléans
Funding period: 01/2020 – 12/2021
Team
Description
Project-related person exchange program with France.
PlasNow - Transport of biologically relevant molecules from the plasma discharge to the biological target in controlled (humid) environments
Funding source: DFG
Project ID: 430219886
Principal investigators: P. Awakowicz, J. Golda
Funding period: 2019 - ongoing
Team
Description
The project aims to gain further insight into the chemical and physical influence of a non-thermal atmospheric pressure plasma on biological tissues such as skin with a view to efficiency and healing-promoting effects.NO is known as the most important trigger element in wound healing in the human body and especially in skin tissue. Besides NO itself, NO derivatives (NODs) such as nitrates, nitrites and s-nitroso proteins play a key role especially for long-term effects in metabolism. We therefore want to focus on the NO pathway from the gas phase into the liquid by quantifying NO and NODs and on the influence of humidity in a controlled atmosphere - humidity that is always available in the atmosphere and in the human body and provides species such as O, H or OH. Due to the complexity of the plasma/atmosphere/liquid/biomolecule system, the parameters need to be controlled as precisely as possible to achieve fundamental understanding. We will therefore use a DBD and a µAPPJ that cover almost the entire range of plasma applications:
We limit the parameter range to answer the following research questions:- How do NO/NOD concentrations, distributions and fluxes evolve and shift from the source via the fluid to the final destination - the biomolecule - how does NO production in plasma influence the flux to skin tissue? What influence do humidity and especially OH have on the production or loss of NO and its derivatives?- How do environmental parameters such as humidity or fluid composition, which provide species such as O and OH, influence these properties?- To what extent can NO(D) and OH production be optimized for both plasma sources by varying gas mixing and external electrical parameters? To this end, we will adapt and investigate the yield of the sources in collaboration with partners. This will be done in an adapted for all available vessel that allows the operation of both sources in different atmospheres. To overcome the well-known problems of measuring at the liquid-gas interface and in the liquid, we use a combined approach.
We will use bio-sensors in a specialized measuring probe that can also be used in the analytical systems of a cooperation partner (Metzler-Nolte). In addition, we want to develop light-fiber-based spectroscopic diagnostics that allow detection with high spatial resolution in liquids. Our second cooperation partner (Christoph Suschek) is investigating the effects of these quantified molecules in vivo.