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Proceeding of: Sixth International Conference on Tethers in Space, Madrid, June 12-14, 2019 The Electrodynamic Tether Technology for Passive Consumable-less Deorbit Kit (E.T.PACK) is a project aimed at the development of a deorbit kit based on low-work-function Tether (LWT) technology, i.e., a fully passive and electrically floating system made of a long conductive tape coated with a low-work-function material. The LWT interacts passively with the environment (ambient plasma, magnetic field, and solar radiation) to exchange momentum with the planet's magnetosphere, thus enabling the spacecraft to de-orbit and/or re-boost without the need for consumables. The main goal is to develop a deorbit kit and related software with Technology Readiness Level 4 and promote a follow-up project to carry out an in-orbit experiment. The planned kit in the experiment has three modes of operation: fully passive LWT and conventional electrodynamic tether equipped with an active electron emitter in passive and active modes. Several activities of the project pivot around the C12A7 : e- electride, which will be used in four hardware elements: (i) LWT (ii) hollow cathode, (iii) photo-enhanced thermionic emission device to convert solar photon energy into electrical energy, and (iv) a hollow cathode thruster. These elements, some of which do not belong to the deorbit kit, are synergetic with the main stream of the project and common to some tether applications like in-orbit propulsion and energy generation. This work explains the activities of E.T.PACK and the approach for solving its technological challenges. After reviewing past progresses on electrodynamic tethers and thermionic materials, we present a preliminary concept of the kit for the in-orbit experiment, some simulation results, and the key hardware elements. This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 828902 (E.T.PACK project). GSA work is supported by the Ministerio de Ciencia, Innovaci on y Universidades of Spain under the Grant RYC-2014-15357. SN work is supported by Comunidad de Madrid (Spain) under the Grant 2018/T2IND/11352

The corrosion behaviour of Si 3 N 4 ceramics with constant composition (Y 2 O 3 –Al 2 O 3 additives) but of different shapes – plate, cylinder and ball – was investigated in 0.5 mol/l H 2 SO 4 at 90 °C. The corrosion kinetics were measured using weight losses and thickness of the corrosion layers. The investigation showed that the corrosion depends on the shape of the samples. The differences in corrosion kinetics cannot be explained by the shrinking core mechanism. They are caused by different formation rates of the passivating SiO 2 -rich layers in the corroded materials.

The silver paste composition for the front side has a strong influence on the firing behaviour, contact formation and resulting efficiency of the solar cell. It is state of the art that the paste glass is needed for etching the ARC silicon nitride during firing and also plays a major role for the transport of silver to the silicon surface. However, the kinetics of the silver transport is still under discussion. A main challenge to understand the underlying mechanisms is the analysis of the microstructure evolution of the paste during firing in the high speed PV firing cycle. In this work PV high speed firing conditions were simulated by usage of a simple laboratory furnace. The microstructural evolution of a model paste was observed and correlated to obtained contact resistances. Moreover, systematic variations of the paste glass were investigated. The overall contact formation kinetics can be divided into two independent but strongly interacting single kinetic phenomena: (i) the reaction kinetics at the wafer surface and (ii) the phase transport kinetics of the silver paste. The reaction kinetic at the wafer surface is composed by three important single reactions: silver solution and precipitation in the amorphous interface layer, interface layer growth, and silicon etching. The phase transport kinetics of the metallization paste determines the quantity of glass that is mixed with the etching products in the interface layer and is dominated by the densification rate of the silver powder and the viscous flow of the paste glass. The paste glass has crucial influence for both kinetics (i) and (ii). In this study the paste glass chemistry has a dominating impact compared to the glass rheology. By an appropriate choice of the raw materials regarding the sinter behaviour and targeted selection of the powder properties substantial control over the paste contacting performance is possible.