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Application fields

Reactive plasmas are among the most important working mediums in the industry. Plasma processes are state-of-the-art, particularly for activation, cleaning, coating and etching. Careful use of resources and compliance with ever more rigorous quality requirements are necessary for economical and environmental reasons and these aspects require research and development activities. Measuring the concentration of important plasma components, such as radicals or stable byproducts, and ascertaining their temporal behavior, enables statements to be made concerning the dominant processes, e.g. for layer deposition or for etching. Monitoring of key species, which due to their high reactivity are extremely short-lived and occur in small concentrations, gives users a unique tool for controlling plasmas with which the process is optimized and the treatment results become reproducible. This approach has already been successfully implemented in the semiconductor industry. 

The plasma nitriding method is one of the most important methods for mediating a higher surface hardness of workpieces. Higher surface hardness increases resistance to abrasive, adhesive and corrosive wear of these components. Together with our partner Freiburg University of Mining and Technology, at the INP a new procedure for nitriding is being developed that should overcome the disadvantages of the existing technology. Through an innovative process design, so-called active screen plasma nitriding avoids effects (hollow cathode effect, arcing, boundary effects) that result in an inhomogeneous machining of the workpiece, e.g. through localized melting or sputtering. For this procedure the INP is working out a new process control based on infrared laser absorption spectroscopy, that is coupled with the electrical power supply. The essential main species in this process has already been identified. Its concentration constitutes a control parameter that enables active adaptation of process conditions, and thus the optimization of the hardening process.   

High-accuracy verification of gases in very low concentrations is important in the medical sector, for environmental protection, in safety technology and in many other areas. Unlike other measurement methods in special laboratories, analysis of trace gases via laser absorption spectroscopy offers many advantages, such as fast measuring times and low detection limits. This method also offers clear measurement results without interfering cross-sensitivities. For realization of high sensitivities, extending down into the ppt range, methods are used at the INP that combine modern infrared laser light sources and optical resonators. After successfully validating the suitability of this technology for provision of compact transportable, ultra-sensitive, multi-component trace gas sensors, currently a prototype based on this technology is being developed at the INP as part of a transfer project. 

Atmospheric pressure plasmas are increasing in significance, and are opening up new application fields, such as plasma synthesis, plasma medicine or decontamination. However, due to their characteristics, it is difficult to make statements concerning composition of these plasmas, and other important plasma parameters. Classic plasma diagnostic methods are either unusable or they can only be used with limitations due to the high density, high collision rates and short lifetimes. Modern imaging and spectroscopy methods (e.g. streak camera, time-correlated single-photon counting) offer the possibility of analyzing electrical breakdown and making statements concerning the strength of the electric field. Here important contributions can be made towards interpreting and controlling these sources. Moreover, in cooperation with Oxford University, the INP succeeded in detecting the hydrogen peroxl radical in the effluents of a non-thermal argon plasma jet in air, via optical feedback cavity-enhanced absorption spectroscopy method. This method makes available the high sensitivity desired for detection of reactive, short-lived species, and consequently should be further extended in the future, to help explain the active mechanisms and develop approaches for process control.


Project topics

Within the framework of the project funded by the German Research Foundation (DFG), "Development of new plasma-assisted methods for thermal-chemical boundary layer treatments of ferrous materials with an active screen of carbon", in cooperation with the Freiburg University of Mining and Technology, the foundations should be laid for development of a new method for boundary layer treatment of ferrous materials with an active screen of carbon reinforced carbon (CFC).

The objective of the project is to research the essential active mechanisms of this plasma diffusion treatment in various media, particularly carbon-containing media. For this purpose, on a laboratory reactor at the INP, and at an industry-oriented facility of the Freiberg University of Mining and Technology, IR-absorbtion and optical emissions spectroscopic investigations are underway to analyze the plasma-chemistry reactions in conjunction with the achieved treatment results, and to derive parameters for controlled generation of carburized and nitrocarburized boundary layers with defined properties, as well as safe process control. 

Project manager:
Prof. Jürgen Röpcke
Phone: +49 3834 - 554 444
roepcke@inp-greifswald.de

As part of the special research area, "Fundamentals of Complex Plasmas", the objective of this subproject is investigation of the fundamental kinetics of transient species in plasmas with non-equilibrium properties, and their interaction with surfaces. Questions concerning the complex chemical reactions, such as absolute concentration of radicals and stable molecules, can be analyzed and answered based on measurements for relevant plasma parameters, such as the absolute concentration of radicals and stable molecules; these measurements employ infrared laser absorption spectroscopy methods. Investigations focus on typical low-pressure plasmas, such as microwave and RF plasmas, as well as dielectric-barrier discharges (DBD) at atmospheric pressure.

In addition to quantitative detection of transient species in the plasma bulk, via resonator-based laser absorption spectroscopy, using evanescent wave technologies, the interactions of these transient species with solid body surfaces in the plasma, such as adsorption and desorption are also being examined. The results flow into theoretical models for molecular plasmas, in order to obtain an in-depth understanding of the plasma-chemistry and the interaction of transient species with surfaces.

Project manager:
Prof. Jürgen Röpcke
Phone: +49 3834 - 554 444
roepckeinp-greifswaldde

As part of the joint project funded by the German Federation of Industrial Research Foundations (AiF), "Use of a plasma torch for production of ultra-pure group III nitride semiconductor targets", in cooperation with the Leibniz Institute for Crystal Growth (IKZ) in Berlin and four industrial partners, work is underway on development of a microwave-assisted thick-film plasma deposition system and a deposition technology for AIN targets. The objective is to also cost-effectively manufacture AIN targets of greater thickness in the future, based on this technology.

As an outstanding feature, the thick-film plasma deposition system will have an optical measuring system that enables analysis of temperature distribution and type of gaseous species in the plasma torch, and thus derivation of process control parameters from these datasets. To do this, among other things with optical emissions spectroscopy, as well as IR absorption spectroscopy, fundamental correlation studies are being conducted at the INP to identify and quantify plasma-based control parameters.   

Project manager:
Dr. Mario Hannemann
Phone: +49 3834 - 554 3856
hannemanninp-greifswaldde

The objective of the transfer project, funded by the Leibniz Association, is scientific exploitation of the knowledge available at the INP Greifswald concerning quantum cascade laser mid-infrared cavity enhanced absorption spectroscopy (QCL-MIR-CEAS). This is a method for detecting trace gases that uses modern infrared laser light sources and optical resonators to boost sensitivity.

With development of the prototype of a compact, transportable, ultra-sensitive multi-component trace gas sensor based on QCL-MIR-CEAS, which is planned as part of the project, a new device class will be established for research and industry. The system will be suitable for a variety of implementation scenarios involving highly-sensitive, molecular trace gas detection that require detection limits in the ppt range. For example, these scenarios include monitoring of technological processes, monitoring of pollutant emissions, breath gas analysis, and detection of hazardous substances. 

Project manager:
Dr. Jean-Pierre van Helden
Phone: +49 3834 - 554 3811
jean-pierre.vanheldeninp-greifswaldde

In this project, funded by the DFG, in cooperation with the Laboratory of Plasma and Energy Conversion (LAPLACE) at the University of Toulouse (France), development and formation of non-thermal atmospheric pressure plasmas are being investigated for surface coating applications. Plasmas at atmospheric pressure, such as dielectric barrier discharge, as a rule do not form a uniform plasma, and this can cause inhomogeneous coating results. Particularly in gas atmospheres with precursor molecules, to this point in time an understanding of the discharge physics has been lacking. Inversely, a change of the surface properties in the coating process results in a change of the plasma parameters.

Thus, control of the processes is still difficult, particularly at high power levels. In the project, the different discharge regimes (single-filaments, self-organized structures in so-called patterned discharges, diffuse discharges) are investigated under process-relevant operating conditions via systematically established electrical, optical, and spectroscopic methods. The goal is to carry out which mechanisms and surface properties are responsible for control of the plasma parameters and structure formation in the gas discharges.   

Project manager:
Prof. Dr. Ronny Brandenburg
Phone: +49 3834 - 554 3818
brandenburg@inp-greifswald.de


Publications

Hamann, S.; Burlacov, I.; Spies, H.-J.; Biermann, H.; Röpcke, J.:
Spectroscopic investigations of plasma nitriding processes: A comparative study using steel and carbon as active screen materials
DOI: 10.1063/1.4980039, J. Appl. Phys. 121 (2017), p. 153301

Lang, N.; Macherius, U.; Wiese, M.; Zimmermann, H.; Röpcke, J.; van Helden, J.-H.:
Sensitive CH4 detection applying quantum cascade laser based optical feedback cavity-enhanced absorption spectroscopy 
DOI: 10.1364/OE.24.00A536, Opt. Express 24 (2016), p. 257529 

Gianella, M.; Reuter, S.; Lawry Aguila, A.; Ritchie, G.-A.-D.; van Helden, J.-P.:
Detection of HO2 in an atmospheric pressure plasma jet using optical feedback cavity-enhanced absorption spectroscopy 
DOI: 10.1088/1367-2630/18/11/113027, New J. Phys. 18 (2016), p. 113027 

Nave, A.-S.-C.; Baudrillart, B.; Hamann, S.; Bénédic, F.; Lombardi, G.; Gicquel, A.; van Helden, J.-H.; Röpcke, J.:
Spectroscopic study of low pressure, low temperature H2-CH4-CO2 microwave plasmas used for large area deposition of nanocrystalline diamond films. Part II: on plasma chemical processes 
DOI: 10.1088/0963-0252/25/6/065003, Plasma Sources Sci. Technol. 25 (2016), p. 065003  

Nave, A.-S.-C.; Baudrillart, B.; Hamann, S.; Bénédic, F.; Lombardi, G.; Gicquel, A.; van Helden, J.-H.; Röpcke, J.:
Spectroscopic study of low pressure, low temperature H2-CH4-CO2 microwave plasmas used for large area deposition of nanocrystalline diamond films. Part I: on temperature determination and energetic aspects 
DOI: 10.1088/0963-0252/25/6/065002, Plasma Sources Sci. Technol. 25 (2016), p. 065002 

Brandenburg, R.:
Dielectric barrier discharges: progress on plasma sources and on the understanding of regimes and single filaments
DOI: 10.1088/1361-6595/aa6426, Plasma Sources Sci. Technol. 26 (2017), p. 053001 

Contact

Leibniz Institute for Plasma Science and Technology
Felix-Hausdorff-Str. 2
17489 Greifswald

Prof. Dr. Ronny Brandenburg
Programme Manager "Plasma Chemical Processes"

Phone: +49 3834 - 554 3818
Fax: +49 3834 - 554 301

brandenburginp-greifswaldde
www.leibniz-inp.de

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