Non-Maxwellian Electron Energy Probability Functions in the plume of a SPT-100 Hall thruster

We present measurements of the electron density, the effective electron temperature, the plasma potential, and the electron energy probability function (EEPF) in the plume of a 1.5 kW-class SPT-100 Hall thruster, derived from cylindrical Langmuir probe measurements. The measurements were taken on the plume axis at distances between 550 and 1550 mm from the thruster exit plane, and at different angles from the plume axis at 550 mm for three operating points of the thruster, characterized by different discharge voltages and mass flow rates. The bulk of the electron population can be approximated as a Maxwellian distribution, but the measured distributions were seen to decline faster at higher energy. The measured EEPFs were best modelled with a general EEPF with an exponent alfa between 1.2 and 1.5, and their axial and angular characteristics were studied for the different operating points of the thruster. As a result, the exponent alfa from the fitted distribution was seen to be almost constant as a function of the axial distance along the plume, as well as across the angles. However, the exponent alfa was seen to be affected by the mass flow rate, suggesting a possible relationship with the collision rate, especially close to the thruster exit. The ratio of the specific heats, the gamma factor, between the measured plasma parameters was found to be lower than the adiabatic value of 5/3 for each of the thruster settings, indicating the existence of non-trivial kinetic heat fluxes in the near collisionless plume. These results are intended to be used as input and/or testing properties for plume expansion models in further work.This work was performed in the framework of the 'Model and Experimental validation of spacecraft-thruster Interactions (erosion) for electric propulsion thrusters plumes' (MODEX) project. MODEX is a collaboration between Airbus-DS, ESA, UC3M, ONERA, CNRS-ICARE and KTH aiming to provide a better understanding of the plasma properties in the far-plume of a Hall thruster. The project aimed at providing experimental measurements to better constrain the modelling, and therefore includes both the theoretical/modelling aspect (UC3M and ONERA) and the experimental aspect (KTH, CNRS, ESA and Airbus-DS). The test campaign was conducted at ESA/ESTEC in April-May 2017, using a SPT-100 Hall thruster provided by Airbus-DS. G Giono and J T Gudmundsson were partially supported by the Swedish Government Agency for Innovation Systems (VINNOVA) contracts no. 2016-04094 and 2014-0478, respectively

A Very High-Order Accurate Staggered Finite Volume Scheme for the Stationary Incompressible Navier–Stokes and Euler Equations on Unstructured Meshes

International audienceWe propose a sixth-order staggered finite volume scheme based on polynomial reconstructions to achieve high accurate numerical solutions for the incompressible Navier-Stokes and Euler equations. The scheme is equipped with a fixed-point algorithm with solution relaxation to speed-up the convergence and reduce the computation time. Numerical tests are provided to assess the effectiveness of the method to achieve up to sixth-order con-2 Ricardo Costa et al. vergence rates. Simulations for the benchmark lid-driven cavity problem are also provided to highlight the benefit of the proposed high-order scheme

On stabiliy analysis of staggered schemes

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Enhancement of Lagrangian slide lines as a combined force and velocity boundary condition

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Non-Maxwellian electron energy probability functions in the plume of a SPT-100 Hall thruster

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Validation of the Peritraumatic Dissociative Experiences Questionnaire and Peritraumatic Distress Inventory in school-aged victims of road traffic accidents

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a posteriori stabilized sixth-order finite volume scheme for one-dimensional steady-state hyperbolic equations

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A leader in an emerging new international market: the determinants of French wine exports, 1848–1938

The objective of this article is to provide an in-depth study of France''s performance in the new international wine market that began to take shape from the middle of the nineteenth century. We analyse the main determinants of its success in exporting ordinary and high-quality wine using a gravity model for both types of wine. The article shows how France lost foreign markets in the ordinary wine sector, due to difficulties in maintaining its exports, which resulted from the decrease in production caused by the phylloxera plague and increasing competition from growing numbers of producers who were more efficient at producing these types of wines. However, in the high-quality wine market, French exporters enjoyed considerable success, increasing their exports thanks to their efforts to offer a product that was highly valued abroad and the use of modern marketing and sales techniques. The exports benefited from the fall in transport costs and French colonial expansion. However, exports of both products were severely affected by a series of major events, including the First World War, the Russian Revolution, Prohibition in the US, and the Great Depression. This case study of the wine market shows that the collapse of the first globalization was not the same for all products

A Class of Low Dissipative Schemes for Solving Kinetic Equations

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