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Plasma-based CO 2 conversion is a promising pathway towards greenhouse gas recycling. In the corresponding research field, various types of plasma reactors are applied for carbon dioxide dissociation. So far, spatial inhomogeneities of the specific energy (SEI) distribution in plasma generators, e.g., induced by non-uniform heating or an inhomogeneous mass distribution, are not the focus of the investigations. In this work, the spatial inhomogeneity of mass-specific enthalpy in the plasma jet of the inductive plasma generator IPG4 at the Institute of Space Systems (IRS) is examined. For this purpose, the mean mass-specific enthalpy as well as the radial distribution of the local enthalpy are measured using plasma probes. Moreover, the influence of the determined specific enthalpy inhomogeneity on the CO 2 splitting performance is quantified. It is shown that an inhomogeneous radial distribution of the specific energy can significantly lower the carbon dioxide conversion, compared to a homogeneous case. With regards to IPG4, the performance reduction is 16%. • Measurement of mean and local mass-specific enthalpy in a high-power CO 2 plasma. • Determination of mass flux distribution in a plasma jet. • Spatial inhomogeneity of specific energy input lowers CO 2 splitting performance in plasma. [ABSTRACT FROM AUTHOR]

To investigate the dissociation and recombination processes in a plasma jet, the characterization of its composition is important. For this purpose, an automated fitting algorithm for emission spectroscopic measurements, based on the radiation simulation tool PARADE, is developed. The algorithm is demonstrated by qualitatively analyzing single carbon dioxide spectra of the inductive plasma generator IPG4, operated at 125 kW anode power with a CO 2 mass flow rate of 2.2 g/s. The species O, C, CO, CO+, CN and C 2 are fitted with regards to number density, as well as vibrational and rotational temperature. A radial analysis of species composition is performed at two axial positions in the plasma jet. The results show different regions inside the plasma, suggesting increasing CO dissociation towards the centerline, as well as recombination of atomic carbon with molecular nitrogen. Moreover, the species composition distribution is found to be an indicator for the flow conditions in underexpanded free turbulent plasma jets. • Development of spectral fitting algorithm for emission spectroscopy. • Fitting of CO 2 spectra of inductive plasma generator at two axial positions. • Radial analysis of plasma species density distribution performed. • Plasma composition as indicator for turbulent free jet plasma flow. [ABSTRACT FROM AUTHOR]