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We demonstrate the calculation of solar wind electron bulk parameters fromrecent observations by Solar Wind Analyser Electron Analyser System on boardSolar Orbiter. We use our methods to derive the electron bulk parameters in atime interval of a few hours. We attempt a preliminary examination of thepolytropic behavior of the electrons by analyzing the derived electron densityand temperature. Moreover, we discuss the challenges in analyzing theobservations due to the spacecraft charging and photo-electron contamination inthe energy range < 10 eV.  Aims: We derive bulk parameters of thermal solar wind electrons by analyzingSolar Orbiter observations and we investigate if there is any typicalpolytropic model that applies to the electron density and temperaturefluctuations.  Methods: We use the appropriate transformations to convert the observationsto velocity distribution functions in the instrument frame. We then derive theelectron bulk parameters by a) calculating the statistical moments of theconstructed velocity distribution functions and b) by fitting the constructeddistributions with analytical expressions. We firstly test our methods byapplying them to an artificial data-set, which we produce by using the forwardmodeling technique.  Results: The forward model validates the analysis techniques which we use toderive the electron bulk parameters. The calculation of the statistical momentsand the fitting method determines bulk parameters that are identical withinuncertainty to the input parameters we use to simulate the plasma electrons inthe first place. An application of our analysis technique to the data reveals anearly isothermal electron "core". The results are affected by the spacecraftpotential and the photo-electron contamination, which we need to characterizein detail in future analyses.

Deriving the bulk properties of solar wind electrons observed by Solar Orbiter: A preliminary study of electron plasma thermodynamics