Advances in wave-plasma modelling in ECR thrusters

Proceeding of: Space Propulsion Conference, SP 2018,14-18 mayo, SevillaThis paper presents the development status of the simulation tool THaMES (Time-Harmonic Maxwell Equations Solver) that aims to reproduce the electromagnetic (EM) wave propagation inside an ECR plasma thruster to study the ECR resonance absorption and wave propagation. THaMES allows the use of a planar domain filled with arbitrary cold magnetized inhomogeneous plasmas, specifying parameters such as the electron plasma density, the applied magnetic field or the effective collisional rate. The simulation relies on MFEM discretization library.The research leading to these results has received funding from the European Union H2020 Program under grant agreement number 730028 (Project MINOTOR)

Cálculo de un púlper y sus instalaciones complementarias en una fábrica de papel

El presente trabajo de fin de grado tiene como objetivos, un estudio de la viabilidad técnica y económica de la implantación de un púlper como alternativa a otro púlper ya existente de tecnología obsoleta de manejo muy manual. Se pretende el diseño de un púlper vertical de baja consistencia, para tratar 250 toneladas diarias de papel reciclado en una fábrica de papel incluyendo un análisis económico para ver la viabilidad del proyecto. Proceso de pulpeado de papel reciclado o papelote reciclado para su posterior utilización en la fábrica de papel, así como el proceso global de fabricación de papel a partir de diferentes materias primas. Producción de pulpa y papel, centrándose en la producción de papel a partir de papel reciclado, ya que es el método predominante actualmente.Departamento de Química OrgánicaGrado en Ingeniería Químic

Enabling Practical IPsec authentication for the Internet

On the Move to Meaningful Internet Systems 2006: OTM 2006 Workshops (First International Workshop on Information Security (IS'06), OTM Federated Conferences and workshops). Montpellier, Oct,/Nov. 2006There is a strong consensus about the need for IPsec, although its use is not widespread for end-to-end communications. One of the main reasons for this is the difficulty for authenticating two end-hosts that do not share a secret or do not rely on a common Certification Authority. In this paper we propose a modification to IKE to use reverse DNS and DNSSEC (named DNSSEC-to-IKE) to provide end-to-end authentication to Internet hosts that do not share any secret, without requiring the deployment of a new infrastructure. We perform a comparative analysis in terms of requirements, provided security and performance with state-of-the-art IKE authentication methods and with a recent proposal for IPv6 based on CGA. We conclude that DNSSEC-to-IKE enables the use of IPsec in a broad range of scenarios in which it was not applicable, at the price of offering slightly less security and incurring in higher performance costs.Universidad de Montpellier IIPublicad

Plasma detachment in a propulsive magnetic nozzle via ion demagnetization

Plasma detachment in propulsive magnetic nozzles is shown to be a robust phenomenon caused by the inability of the internal electric fields to bend most of the supersonic ions along the magnetic streamtubes. As a result, the plasma momentum is effectively ejected to produce thrust, and only a marginal fraction of the beam mass flows back. Detachment takes place even if quasineutrality holds everywhere and electrons are fully magnetized, and is intimately linked to the formation of local electric currents. The divergence angle of the 95%-mass flow tube is used as a quantitative detachment performance figure.This work has been sponsored by the Air Force Office of Scientific Research, USAF (FA8655-12-1-2043) and Spain R & D National Plan (AYA-2010-61699

Fully magnetized plasma flow in a magnetic nozzle

A model of the expansion of a plasma in a magnetic nozzle in the full magnetization limit is presented. The fully magnetized and the unmagnetized-ions limits are compared, recovering the whole range of variability in plasma properties, thrust, and plume efficiency, and revealing the differences in the physics of the two cases. The fully magnetized model is the natural limit of the general, 2D, two-fluid model of Ahedo and Merino [Phys. Plasmas 17, 073501 (2010)], and it is proposed as an analytical, conservative estimator of the propulsive figures of merit of partially magnetized plasma expansions in the near region of the magnetic nozzle.This work has been supported by the Spanish R&D National Plan, Grant No. ESP2013-41052-P

Effect of the plasma-induced magnetic field on a magnetic nozzle

A two-fluid, two-dimensional model of the plasma expansion in a divergent magnetic nozzle is used to investigate the effect of the plasma-induced magnetic field on the acceleration and divergence of the plasma jet self-consistently. The induced field is diamagnetic and opposes the applied one, increasing the divergence of the magnetic nozzle and weakening its strength. This has a direct impact on the propulsive performance of the device, the demagnetization and detachment of the plasma, and can lead to the appearance of zero-field points and separatrix surfaces downstream. In contrast, the azimuthal induced field, albeit non-zero, is small in all cases of practical interest.Initial work was sponsored by the Air Force Office of Scientific Research, Air Force Material Command, USAF (FA8655-12-1-2043). Additional support was provided by Spanish R&D National Plan (grant number ESP2013-41052-P)

Contactless steering of a plasma jet with a 3D magnetic nozzle

A 3D, steerable magnetic nozzle (MN) is presented that enables contactless thrust vector control of a plasma jet without any moving parts. The concept represents a substantial simplification over current plasma thruster gimbaled platforms, and requires only a small modification in thrusters that already have a MN. The characteristics of the plasma expansion in the 3D magnetic field and the deflection performance of the device are characterized with a fully magnetized plasma model, suggesting that thrust deflections of 5 degrees - 10 degrees are readily achievable.This work has been supported by the Spanish R&D National Plan under grant number ESP2016-75887-P

Influence of electron and ion thermodynamics on the magnetic nozzle plasma expansion

Proceeding of: 33rd International Electric Propulsion Conference (IEPC 2013)A two-fluid 2-D model of the supersonic plasma flow in a propulsive magnetic nozzle (MN) is extended to include simple electron and ion thermodynamics to study the effects of electron cooling and ion thermal energy on the expansion. A faster electron cooling rate is seen to reduce plasma jet divergence, increase radial rarefaction, and enhance detachment from the closed magnetic lines. Ion thermal energy is converted to directed kinetic energy by the MN without the mediation of an ambipolar electric field, and alters the electric response of the plasma.This work has been supported by the European Space Agency project 'Helicon Plasma Thruster for Space Missions', grant number 4000107292/12/NL/CO. Additional support has been provided by Spain's R&D National Plan (Project AYA-2010-61699)

Three-dimensional geomagnetic field effects on a plasma thruster plume expansion

A 3D hybrid particle-in-cell code with a partially-magnetized fluid electron model is presented and applied to study the effects of a uniform external geomagnetic field on an expanding plasma thruster plume at three different angles. Electron currents are governed by both the magnetic field and collisional effects with the heavy ions and neutrals. While an axial magnetic field (parallel to the plume axis) induces azimuthal electric currents and an observable plume channeling, an oblique field produces non-trivial asymmetric deformations of the plume cross-section, and induces axial-radial electric current loops. A center of mass analysis of the plasma plume demonstrates that the electron response produces an electric field that balances the Lorentz force deflection on the ions, so that no net plume momentum deflection is observed.The primary funder of this research was the Comunidad de Madrid (Spain), under PROMETEO-CM project, with grant number Y2018/NMT-4750. Initial support was provided by the Ministerio de Economía y Competitividad (Spain), under project ESP2016-75887-

Spacecraft-plasma-debris interaction in an ion beam shepherd mission

This paper presents a study of the interaction between a spacecraft, a plasma thruster plume and a free floating object, in the context of an active space debris removal mission based on the ion beam shepherd concept. The analysis is performed with the EP2PLUS hybrid code and includes the evaluation of the transferred force and torque to the target debris, its surface sputtering due to the impinging hypersonic ions, and the equivalent electric circuit of the spacecraft-plasma-debris interaction. The electric potential difference that builds up between the spacecraft and the debris, the ion backscattering and the backsputtering contamination of the shepherd satellite are evaluated for a nominal scenario. A sensitivity analysis is carried out to evaluate quantitatively the effects of electron thermodynamics, ambient plasma, heavy species collisions, and debris position