30th Spacecraft Plasma Interaction Network in Europe (SPINE) meeting

Dec 6, 2023, 2:00 PM → Dec 8, 2023, 2:00 PM Europe/Amsterdam

Einstein (ESA/ESTEC)

Fabrice Cipriani (ESA), Fredrik Leffe Johansson (ESA/ESTEC), Gregoire Deprez (ESA)

The SPINE workshop is an open forum on new  research and technological results, needs and plans in the area of spacecraft plasma interactions. 

Contributions are welcome in all topics of interest for the European spacecraft/plasma community at large.

For the 30th edition contributions covering the following domains are encouraged :

• Platform effects on Plasma measurements onboard Scientific missions (JUICE, Bepi Colombo, Solar Orbiter, etc…)

 

• Dust charging effects and interactions with systems in the context of lunar exploration and e.g. Deep Space Gateway

 

• Electrical propulsion and plumes interaction with spacecraft, modelling and experiments, flight data analysis

 

• High Performance computing and application to numerical codes for spacecraft - plasma interactions

 

• Evolution of Internal Charging analyses and models, real time approaches 
   

Contributions addressing all other aspects such as :

• Evolution of surface and internal charging environments and standards  
• Material properties (measurements, new materials, etc ..)
• Ground and space based experiments for surface and internal charging
• Electric propulsion driven plasma environments, electrical orbit raising
• Innovative numerical methods and approaches for surface and internal charging applications
• Charging of Cubesats, Nanosats, effects on (miniaturised) instrumentation
• Plasma (instrumentation and spacecraft electrostatic cleanliness)
• Simulation tools performances, current and future developments, interoperability between tools

are also welcome.

The registration and abstract submission deadline have been extended until November 16th 2023 18:00 CEST.  

Looking forward to meet you in ESTEC Campus !

https://www.esa.int/About_Us/ESTEC/European_Space_Research_and_Technology_Centre_ESTEC2

For this 30th SPINE workshop, a tour of ESTEC facilities will be organised. 

Wednesday, December 6

1 30th Spine Welcome

Speaker: Fabrice Cipriani (ESA)

Electric propulsion-1

2 (Withdrawn) Validation of Hall-Effect Thruster Plume Modelling using the VSTRAP Plasma Simulation Tool

OHB is one of the three main system integrators of Europe and has launched several Geo-stationary satellites (HAG-1, EDRS, MTG). Recent missions such as H2SAT uses electric propulsion (EP) system for orbit control. Such an EP system has an impact on the spacecraft design through undesirable plume interactions. The charged ions can degrade the spacecraft during station keeping or orbit raising maneuvers. Different effects could appear such as unwanted forces and torques, thermal fluxes, materials sputtering and contamination, which could lead to significant performance loss.

Several physical characteristics of this plasma plume need further investigation, which demands for improvement of the simulation techniques. The simulation of EP thrusters in general is done by software tools e.g., PICplus, Hallis, SPIS, VSTRAP or openPlumeEP. Thruster simulation models are usually validated by matching them with experimental data. In-orbit measurement data of EP thrusters is cost intensive and so far only available from a few missions e.g., Express-A2, Express-A3 or SMART-1. Hence the experimental data to validate EP simulation models is usually taken from on-ground test measurements. The different environment conditions between in-orbit and on-ground measurements impact not only the plume characteristics, but also the ionization process inside the thruster.

Therefore, the plasma generation inside a SPT-100 thruster is simulated with the new developed plasma simulation tool VSTRAP by SPARC Industries, which allows to consider the background pressure during the ionization process. The thruster plume parameter obtained in VSTRAP are then used to set up a thruster model in SPIS. In order to validate the simulation, the energy distribution and current density of SPIS is compared to VSTRAP in the near-field domain and to experimental test data in the far-field.

The presentation at the SPINE meeting aims at summarizing the challenges of simulating the SPT-100 plasma generation with VSTRAP, its characteristics, the comparison with the plasma plume simulated with SPIS as well as with experimental data and the way forward for future applications.

Speaker: Ms Zoe Angelow (OHB System AG)

Abstract_SPINE_Angelow.pdf

3 Three-dimensional simulations of a Hall thruster magnetized plume in a vacuum chamber

EP2PLUS is a 3D hybrid particle/fluid simulation code for plasma plumes and their interaction with nearby objects. Originally, it was developed for unmagnetized and weakly magnetized plumes with applications for: simulations of active debris removal with impingement of energetic ions, ion thruster optics and beam neutralization, and geomagnetic effects on unmagnetized plume expansions. Currently, it is being upgraded for mildly magnetized plumes for application to Hall thruster plume expansions in facility conditions under the scheme of several European H2020 projects. Firstly, the capabilities of the code, and latest upgrades in terms of modeling and numerical aspects are reviewed. Secondly, simulation results are shown for a direct-drive hall thruster. The electric coupling between its plume, its physical components, and the vacuum chamber is analyzed. The cathode return potential of the thruster versus the stray currents and the floating potential of the vacuum chamber are characterized. In addition, the background pressure is varied to check the dependence of the results on this parameter.

Speaker: Jiewei Zhou (Universidad Carlos III de Madrid)

4 Numerical modelling of plasma erosion with CSiPI: overview of the software and future coupling with SPIS

The response of a material under the impact of energetic ions is an important topic in the space industry, especially with the increasing usage of plasma thrusters. In this context, the numerical modelling of material sputtering under ion bombardment becomes a key element to assess the performances and the lifetime of spacecraft components (such as solar arrays interconnects), as well as the risks induced by the contamination of eroded materials on other satellite surfaces [1], [2] as well as the lifetime of plasma thrusters themselves [3].

To this extent, the ONERA developed CSiPI (Code de Simulation de la Pulvérisation Ionique), a Monte-Carlo code that implements a binary collision approximation model to simulate the collision cascade occurring at the impact of an energetic ion on a material surface [4]. CSIPI is able to represent the dependency of erosion yield to incident energy and incident angle, as well as to simulate other significant values such as angular distribution of eroded particles, which is a major topic for surface contaminaton study.

This work presents an overview of the current capabilities of CSiPI, and compares its results with those obtained with the analytic models currently implemented in SPIS (Spacecraft Plasma Interaction Software). The foreseen efforts related with the further development of CSiPI and its potential coupling with SPIS are discussed as well.

[1] J. T. Yim, ‘A Survey of Xenon Ion Sputter Yield Data and Fits Relevant to Electric Propulsion Spacecraft Integration’, presented at the International Electric Propulsion Conference (IEPC), Atlanta, GA, Oct. 2017. Accessed: Sep. 15, 2023. [Online]. Available: https://ntrs.nasa.gov/citations/20170009068
[2] L. J. Buntrock, C. Volkmar, and K. Hannemann, ‘Sputtering of Mo and Ag with xenon ions from a radio-frequency ion thruster’, Review of Scientific Instruments, vol. 92, no. 4, p. 045109, Apr. 2021, doi: 10.1063/5.0031408.
[3] Y. Garnier, V. Viel, J.-F. Roussel, and J. Bernard, ‘Low-energy xenon ion sputtering of ceramics investigated for stationary plasma thrusters’, Journal of Vacuum Science & Technology A, vol. 17, no. 6, pp. 3246–3254, Nov. 1999, doi: 10.1116/1.582050.
[4] T. Tondu, V. Inguimbert, J.-F. Roussel, and S. D’Escrivan, ‘Hall Effect Thrusters Ceramics Sputtering Yield determination by Monte Carlo Simulation’, presented at the 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Jul. 2008. doi: 10.2514/6.2008-5090.

Speaker: Luca Chiabò (ONERA - The French Aerospace Lab)

abstract_SPINE_lchiabo_et_al_with_Figs.pdf

5 Advancements in EP Thruster and Plume Simulation: Integrating VSTRAP with SPIS and oPEP

Understanding the interaction between electric propulsion (EP) thrusters and spacecraft is crucial for assessing satellite contamination, erosion, and charging. Accurate plume-satellite interaction models play a pivotal role in this context. Often, the availability of experimental plume data is limited, necessitating the use of sophisticated simulation tools. In this presentation, we will delve into the simulation of EP thrusters, specifically gridded ion engines and Hall-Effect thrusters, and the seamless integration of these simulations with the simulation tool VSTRAP. The results obtained from these simulations can be effectively coupled with established codes such as SPIS and ray-tracing tools like OpenPlumeEP.

The simulation toolchain we will discuss extends beyond propellant gases and ions; it also encompasses the emission of sputtered eroded particles from the thruster into the plume. VSTRAP offers a comprehensive approach to estimate not only the behaviour of propellant gas and ions but also the potential effects of sputtered particles on satellite surfaces.

By leveraging this integrated simulation approach, we can gain valuable insights into the influence of EP thrusters on satellites, addressing issues such as contamination, erosion, and charging. This presentation aims to showcase the capabilities of VSTRAP in tandem with SPIS and OpenPlumeEP, offering a robust solution for scenarios where experimental plume data may be lacking.

Speaker: Ullrich Siems (Sparc-Industries)

6 Contamination model in SPIS : overview and the specific case of droplet contamination due to the use of the FEEP and electrospray thrusters

Spacecraft surface contamination is a major topic for space industry as it can limit the duration of a mission [1,2], the interest for this problematic has been renewed due to the interaction between the thrusters exhaust flow and the satellite surface. In this work, the current state of the contamination module developed in SPIS is presented as well as the new developments carried out to take into account the contamination induced by FEEP and electrospray thrusters.

[1] Virginie Inguimbert, Mohamed Belhaj, Marc Villemant, Delphine Faye, and Véronique Perrin. Degradation of
solar absorptivity of thermo-optical materials contaminated by electric propulsion. May 2019.

[2] J. Roussel, T. Tondu, J. Mateo-Velez, E. Chesta, S. D’Escrivan, and L. Perraud. Modeling of FEEP Plume Effects
on MICROSCOPE Spacecraft. IEEE Transactions on Plasma Science, 36(5):2378–2386, October 2008.

Speaker: Marc VILLEMANT (ONERA DPHY-CSE)

abstract.pdf

3:50 PM Coffee

Materials-1

7 Transparent conductive coatings – Preventing spacecraft surface charging with ionic liquids

Spacecrafts are constantly exposed to an influx of charged particles. Accumulations of such particles, for example on the non-conductive cover glasses of solar cells, can have detrimental effects on the spacecraft’s performance, ranging from distorted sensor readings and malfunctions to total loss of the spacecraft, if potential differences are high enough to cause discharges. To avoid this, lightweight, inexpensive, transparent conducting coatings are desirable, all of which can be achieved by ionic liquids. We demonstrate the preparation of ultra-thin films of one of such liquids, 1-Butyl-1-methylpyrrolidinium dicyanamide (BMP DCA), on glass, including thickness characterization. By performing Kelvin Probe Force Spectroscopy, we asses the charge mitigation capabilities of such films when exposed to the electron beam of a scanning electron microscope in an ultra-high vacuum environment, mimicking conditions in space. The charge densities achieved in this procedure exceeded average space conditions by orders of magnitude. Additionally, we also show that such coatings do not significantly alter the power output of commercially available solar cells for space applications. Overall, our results indicate a high potential for ionic liquids to prevent the build up of surface charges on satellites.

Speaker: Mr Mirco Wendt (DLR Neustrelitz / University of Rostock)

8 Electrical properties models for materials in SPIS: current capabilities and perspectives

Electrical properties of materials in space are strongly affected by the environment (plasma interactions with the surfaces, temperature, illumination…). The goal of this presentation is to give a review of the existing models available in the current version of SPIS. In particular, we present the last developments that were made to model the dependence of the dielectrics conductivity on the temperature, electric field and illumination. We also give a review of the currently implemented electron emission models (due to electron, ion, neutral interaction or photo-emission) and propose solutions to improve these models. Moreover, we introduce a new tool recently develop to allow SPIS to upload material parameters from external libraries as inputs for these material models.

Speaker: Ludivine Leclercq (ONERA)

9 Surface Charging Risk Prediction Service in PAGER and extension to advanced mission profils characterisations

Space weather frameworks have beneficed of improvements of environment models and as well through an increase of models coupling simulating the different interplanetary and near Earth involved processes. They now focus on an estimation of the concrete risk for spacecraft or embedded devices. In this logic and representing the state of the current art, PAGER (Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation) is distinguished by the plugging of effect models on the satellites, downstream the environment models, especially about surface charging.

In this frame, Artenum as developed and integrated a complete modelling chain able to simulate, in a reasonable time, the surface charging processes and provide an easy to read surface charging risk prediction forecast. Charging models are run on a set of reference charging cases carefully optimized to be run in a reasonable time, and along a set of predefined orbits. Different charging models have been integrated: a simple 1D surface charging model, SCOne, developed ab-initio for the PAGER project, to give a rapid answer and address rapid charging events, and the reference 3D charging code SPIS-SC, for finer results on a set of more detailed reference charging cases. The results are freely available through simple traffic-light indicators on the PAGER Web site.

Furthermore, analyses of past events, such as on LANL GEO satellites have shown that depending on thresholds on the incoming and secondary currents resulting from several processes. Consequently, the real risk induced by the surface charging process depends deeply on the platform design and selected materials as well as on the incoming plasma flux spectra. This calls into question the relevance of classical indicators such as space-weather indexes used to estimate the concrete charging risks for in-flight platforms. To estimate this point, an analysis of the surface charging PAGER results, recorded over several months of forecast, will be presented for GEO spacecraft and analyzed to compare against the classical indicators.

If PAGER’s results already constitute a very good first risk indicator, they remain limited to a given set of reference charging cases and predefined orbits. To overcome these limitations, a «mission dedicated» charging risk prediction service has been developed on internal Artenum’s funds outside of the PAGER project. This new service providing a forecast for dedicated missions, part of the SpaceSuite offer, will be rapidly presented.

Speaker: Benoît Tezenas du Montcel (Artenum)

10 ESD risk assessment of floating metals with FASTRAD

High energy electrons can penetrate through the spacecraft and charge sensitive elements inside. The build-up of electric charges that can lead to an electrostatic discharge occurs in dielectrics and on floating metals. The internal charging module of FASTRAD was improved to compute the increase in potential of floating metals. We focus on cases where an inverted gradient discharge is likely to occur i.e. where the potential of the metal is lower than the underlying dielectric. Some examples will be presented and discussed.

Speaker: Dr Jérémie Plewa (TRAD)

11 Discussion and recommendations on modelling improvement needs for EP and material properties

Discussion and recommendations on modelling improvement needs for EP and material properties

7:30 PM Optional Dinner

Thursday, December 7

9:00 AM Coffee

Science application

12 Spacecraft charging effects on solar wind electron measurements on board Solar Orbiter spacecraft

Any spacecraft immersed into the solar wind builds up a non-zero electric potential with respect to the local environment by continuously collecting the charged particles from ambient plasma populations and emitting additional charged particle populations, namely photo-electrons and/or secondary electrons, from its surface materials. These electrons of spacecraft origin as well as the electric fields induced in the vicinity of the spacecraft body by the so called spacecraft potential may in turn significantly distort the local plasma conditions and therefore affect any in-situ electron observations and thus potentially modify the derived electron properties. We analyse such effects as seen by the SWA-EAS electron analyser in the variable plasma and electrostatic environment of the Solar Orbiter spacecraft and compare the observed features with numerical simulations using the SPIS (Spacecraft Plasma Interaction System) tool.

Speaker: David Herčík (Institute of Atmospheric Physics CAS)

13 Charging effect on the electron moment measurements with the Mercury Electron Analysers onboard BepiColombo.

BepiColombo ESA/JAXA joint mission is on its route to Mercury. During the cruise phase, three spacecrafts, Mercury Transfer Module (MTM), Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO or Mio) remain in a stack configuration. Moreover, Mio and its instruments are protected from the sun behind the Magnetospheric Orbiter Sunshield and Interface Structure (MOSIF). Several time during the cruise phase, the Mercury Electron Analysers (MEA) were turned on. However, the presence of the MOSIF reduce significantly the field of view of the instruments in two ways: geometrically and with the surface charging of the inner and outer sides of the MOSIF. In this study, we try to simulate MEA measurements with the Spacecraft Plasma Interaction Software. By comparing the simulation and experimental results we discuss how it affects the low energy electron detection and more generally the electron moments measurements.

Speaker: Mathias Rojo

14 Examining the Distribution Function of Spacecraft Emitted Photoelectrons by Using Low-Energy Electron Measurements from the Cluster Spacecraft

Understanding spacecraft electrostatic charging is crucial for interpreting scientific instrument data, particularly data from electron analyzers. In low-density plasma environments, such as the solar wind or the magnetospheric plasma sheet, spacecraft emit electrons when exposed to sunlight and such photoelectrons constitute the largest current collected by the spacecraft. Accurate knowledge of the distribution function of these emitted photoelectrons is important to properly model the proportion of emitted photoelectrons returning to the spacecraft when using the Spacecraft Plasma Interaction Software (SPIS). Laboratory measurements of photoelectron distribution functions indicate that a Maxwellian energy distribution is a good approximation. However, these studies are constrained by monochromatic incident light and materials not exposed to space conditions.This study aims to ascertain the Maxwellian nature of emitted photoelectrons using data from the PEACE electron analyzer onboard the Cluster mission. Initially, we used a SPIS simulation of the Cluster spacecraft in a plasma sheet environment modeling PEACE as a SPIS device. We verify that the user-defined emitted photoelectron distribution aligns with the distribution measured by the simulated PEACE device. Then, leveraging this knowledge, we study the electron distribution in scenarios where the spacecraft potential is significantly high (around ~50V) to elucidate the emitted electron distribution from the spacecraft. Our analysis suggests that the typical distribution function of photoelectrons for a spacecraft in space aligns with a Maxwellian distribution, with an estimated temperature of approximately 2 eV for the best fit.

Speaker: Guillaume Tcherniatinsky (LPP, Palaiseau, France)

15 Towards the systematic correction of Solar Orbiter electron data using SPIS

The Solar Orbiter spacecraft body may interfere with low-energy electron measurements by the Electron Analyser Sensor (EAS) of the Solar Wind Analyser (SWA) instrument. Due to positive spacecraft charging occurring in the solar wind environment, the spacecraft both acts as a focusing lens for solar wind electrons and as an electron source due to processes like photoemission and secondary emission. As a result, measurements made by SWA-EAS at low energy can be significantly affected in terms of actual look directions and count numbers, especially at low energy. The study aims at correcting these measurements by accounting for these disturbances.

We first evaluate Solar Orbiter electrostatic environment by using the SPIS software with an accurate description of the SWA-EAS sensor. SPIS particle detector devices are then used to backtrack electron trajectories and to infer the deflection of electrons before they hit the detectors. Systematic energy shifts are also determined. We establish an algorithm to obtain the corrected phase space density from the raw phase space density measured by SWA-EAS. The simulations are used to assess the impact of Solar Orbiter electrostatic sheath on SWA-EAS data.

Speaker: Guillaume Tcherniatinsky (LPP, Palaiseau, France)

10:30 AM Coffee

Science application-2

16 Spacecraft charging simulations of Comet Interceptor – charging effects at high relative flyby velocities and implications for ion measurements

In 2019, Comet Interceptor was selected by ESA as a new F-class mission. Comet Interceptor will visit a long-period and, ideally, pristine comet that is yet-to-be discovered. For the first time, multipoint measurements will be made in the cometary environment using three spacecraft: spacecraft A (ESA), probe B1 (JAXA) and probe B2 (ESA). All spacecraft will carry plasma instruments allowing, for the first time, a three-dimensional study of the cometary plasma environment. The plasma measurements are, however, expected to be affected by the spacecraft potential.

In this study, we use SPIS to simulate the expected spacecraft potential of probe B1 of Comet Interceptor. We study the spacecraft potential both in the solar wind and in different regions of the cometary plasma environment during the flyby. This is done for different activity levels of the target comet and at different relative flyby velocities. We especially discuss charging processes at high flyby velocities and the corresponding modelling capabilities of SPIS.

Finally, we use particle tracing to study the expected influence of the spacecraft potential on low-energy ion measurements.

Speaker: Sofia Bergman (KTH Royal Institute of Technology)

17 Using SPIS connection to Virtual Observatory to model the electrostatic cleanliness of science missions

Spacecraft in orbit around planet or in the interplanetary medium are immersed in plasma from which they collect charged electrons and ions leading to the electrostatic charging of the surfaces. In addition, energetic impacts of particles or UV photons may lead to the emission of secondary electrons back to the plasma. This latter effect is highly dependent on the exposure and characteristics of the surface material, leading to differential charging. The electrostatic charging can ultimately lead to electrostatic discharges onboard the spacecraft, but even in less dramatic configuration they can perturb the plasma close to the spacecraft, which impacts scientific payload studying either the plasma particles or the electromagnetic fields. The spacecraft charging effect must be taken into account in the processing of the raw measurements from these instruments, but this task reveals itself complicated by the strong variability of the charge levels, themselves correlated to the variability of the environments. Standard methods of calibration use average charge states to process the data, and some studies use charge state estimations based on estimate of the environment parameters at the time of the measurements. However, the data processing usually require a self-consistent processing of the data, using the data themselves to estimate the environment conditions and determine the charge state. In absence of compatibility and link between the measurement databases and the spacecraft charging simulation tools, this task is tedious and limited to particular events. We present here the latest developments of the Spacecraft-Plasma Interaction Software (SPIS) to allow it to access space measurement databases using the SPASE framework to monitor the spacecraft charging effects on instrument measurements. We discuss how the SPASE formalism allows a semi-automated treatment of the database to select and process relevant data. A typical use case is presented with the simulation of the observation of a fast reverse shock in the solar wind by THEMIS.

Speaker: Dr Ludivine Leclercq (ONERA)

18 Simulations of the electrostatic charging in GEO and the flashover current of large platform with flexible solar panels

Abstract: In the frame of the ESA EMAGS 4 project, we perform SPIS simulation of the charging behavior and we assess the ESD inception rate depending of the geometry of the panel and of the electrical materials properties. We consider the changes related to the fact that the telecom platform using flexible solar arrays have significantly increased the size of the solar panel and that the materials of the panel are different from a classical telecom platform. We also investigate the fact that the solar array layout will be not systematically metalized on the rear face creating a completely new electrical configuration on the solar array. From this SPIS simulation, we simulate the flashover current on realistic geometry. From these simulations, we open the discussion on how can we update the FO simulator circuit use in experiments to represent the realistic situation and to test the solar cells coupons.

Speaker: Pierre Sarrailh (ONERA - The French Aerospace Lab)

11:45 AM Discussion

Science applications focus : what can we do better with SPIS ?

12:15 PM Lunch

19 ESTEC Visit

Spacecraft charging

20 Spacecraft Surface Charging Solvers: a Comparison

In the frame of a space project, a fundamental step is the risk assessment of electrostatic charging phenomena by means of a surface charging analysis at satellite level. The charge accumulated on space-exposed surfaces depends strongly on the plasma environment, satellite materials and grounding philosophy. Being smaller and faster with respect to ions, electrons are responsible for the negative absolute potential of satellite surfaces. Charging values can then range from a few volts up to thousands volts based on the electron energy and density, together with the resistivity of the surface material. In fact, grounded conductors charge to smaller absolute values when compared to dielectrics. The potential difference between a conductor and an adjacent dielectric can trigger an electrostatic discharge. Hence, the need of a 3D surface charging analysis.

In Europe, the most used tool to perform this kind of analyses is SPIS (Spacecraft Plasma Interaction Software). Simulations for LEO environments are very time consuming, due to the need of a PIC solver. In order to optimize the time dedicated to set and run a surface analysis, TASI (Thales Alenia Space Italia) evaluated a software tool recently presented to the European market: ANSYS CHARGE PLUS.
The purpose of this work is to compare the results of the same simulation run in both SPIS and CHARGE, setting the same geometry and environmental conditions. To this aim, a general and simplified satellite geometry has been modelled, together with an ECSS suggested worst-case environment.

Throughout the evaluation, the results of the comparison have been extremely promising: the potential equilibrium values are in good agreement with SPIS, and with both TASI heritage and literature in general.

Speaker: Anna Di Fiore (Thales Alenia Space Italia)

Spacecraft Surface Charging Solvers - a Comparison.pdf

21 Simulation of Space Platform Charging in Very Low Earth Orbit with Particle Methods

The persistent challenge posed by the presence of plasma particles inducing charging phenomena on space platforms within orbital environments has long been recognized. These charges carry the potential to inflict damage upon satellite surfaces and electric circuits, especially in the context of electric propulsion systems and Very Low Earth Orbit (VLEO) flights, where interactions between plasma particles and surfaces occur. Understanding the intricate process of space platform charging is crucial for determining the resultant electrostatic potential and, consequently, designing protective measures for spacecraft surfaces.

This study aims to inspect cases of satellites in VLEO, presumably with plasma plumes, seeking explanation on key inquiries: What encompasses the general dynamics of plasma-surface interaction? What is the resulting electric potential structure arising from platform charging? How does the overall charging process evolve with varying altitudes in VLEO? Addressing these questions requires the utilization of advanced numerical tools using Particle-In-Cell (PIC) plasma modelling approach coupled with Monte Carlo collisions to accurately capture plasma flows in the proximity of space platforms. Another asset of this research entails the implementation of 2D/3D modelling for the satellite's geometry, a determinative factor in shaping the overarching electric potential structure.

Additionally, we propose enhancements to the model, encompassing the integration of external circuits in simulations applied to spacecraft surfaces and the incorporation of plasma-surface interaction models (e.g., photon-surface interaction induced by sunlight). These refinements aim to extend the applicability of the model, advancing our comprehension of the intricate interplay between plasma and space platforms in VLEO scenarios.

Speaker: Jan Skácel

22 SURFACE CHARGING ANALYSIS FOR THE COPERNICUS CRISTAL SATELLITE IN LEO AURORAL PLASMA CONDITIONS

The ability to withstand the harsh space environment is one of the key challenges in the design and construction of satellites. One of these special characteristics of space is the plasma environment encountered in orbit. In this presentation the system level charging analysis and simulations for the CRISTAL satellite are presented. As part of the European Copernicus program, the CRISTAL mission is designated to obtain high-resolution sea ice thickness and land ice elevation measurements and includes the capability to determine the properties of snow cover on ice so as to serve Copernicus’ operational products and services of direct relevance to the polar zones. The CRISTAL satellite will therefore be launched into a drifting circular orbit with a semi-major axis of 7061.735 km and an inclination of 92°.
In this orbit the local plasma parameters in the so called auroral zone close to the poles can lead to critical charging of the satellites. The simulations are performed using a three-dimensional satellite model, where the main elements and surfaces are included. The tool for the simulations is the spacecraft plasma interaction software (SPIS). The calculated surface potentials on the satellite are critically reviewed, the possibility for electrostatic discharges (ESD) is analysed and protective measures for the minimization of the risks to the satellite mission are discussed.
Besides the relevant results for the satellite design and safety there will be feedback provided on the performance of the numerical solvers in SPIS. In this context some encountered problems and implemented work-arounds to establish consistent and properly converging simulations of the charging in the auroral zone will be discussed.

Speaker: Christian Imhof (Airbus Denfence and Space GmbH)

Abstract_CRISTAL_LEO_Auroral_Charging_Analysis_20230912.doc

23 Is arcing on Solar Panels a fatality?

A solar panel is a special equipment on a satellite. It is very strongly exposed to charging and radiative space, the solutions of one being the defects of the other. For example, protective glass for solar cells, essential for maintaining the dose effect, and therefore for the lifespan of the underlying cells, generates an assembly of semiconductor, silicone glue and glass which is so conducive to ESD. SA is also the generator of all the power of the satellite, where the slightest bubble of plasma can be transformed into a destructive arc.
The simulation of the electrostatic state, increasingly precise thanks to SPIS, allows us to achieve potential gradient values depending on environmental conditions. But do we have a risk assessment? The answer is no. But then do we ultimately need it? Not always or not necessarily? What a surprise!
Ultimately not so much, when we admit that electrostatic discharge is no longer necessarily the major risk of failure on a solar panel.
We will review the methodologies applied in space to guarantee the maximum immunity of a satellite in its design phase and show that the arc free solar panel is simply the application of this method. The source of the discharge is never more than a choice constrained by available technology or an human error.

Speaker: Denis PAYAN (CNES)

24 What if the loss of the 40/49 Starlink Spacecraft was due to an Electrostatic discharge?

On Thursday, February 3 at 1:13 p.m. EST, Falcon 9 launched 49 Starlink satellites into low Earth orbit from Launch Complex 39A at the Kennedy Space Center in Florida. On February 6, they announced the loss of 40 of the 49 satellites in the middle of a moderate geomagnetic storm. The root cause mentioned would be an increase in the swelling of the atmosphere leading to a 50% increase in atmospheric drag.
However, in an Operational Launch Center it is impossible that this could have happened like they related. Important facts have been deliberately omitted.
What if the loss of all 40 satellites was due to ESD?

Speaker: Denis PAYAN (CNES)

4:25 PM Coffee

Dust charging

25 Modelling and ground testing of lunar dust simulant electrostatic charging under VUV irradiation

Committed for nearly 10 years to the study of electrostatic charging and adhesion of dust in space, ONERA conducts several studies with ESA and the EU through dedicated experimental facilities.
Apollo missions revealed how much dust is problematic, making the safety of future long-term lunar activities a difficult challenge. The absence of atmosphere and the constant ionizing radiation favors a very strong electric charge and a chemical reactivity that make dust stick to almost everything. To protect and preserve the mechanisms, optics, thermal control coatings, sealing and health of astronauts, it is of paramount importance to understand the underlying charging mechanisms of dust under a representative environment, both numerically and experimentally.
ONERA has developed characterization means in order to tackle the problem from several angles. The DROP platform, located in Toulouse, houses a vacuum chamber (under 10-6 mbar) that reproduces the lunar radiative environment (VUV and electron irradiation), a centrifuge for adhesion characterization and a dust deposition chamber with controlled uniformity and coverage rate, validated on a series of powders simulating lunar regolith. This platform is useful to investigate several questions, from the charging behavior of lunar dust simulants under VUV/electron beam to the adhesion forces on technical space-grade materials.
The upcoming lunar missions offer unique opportunities for in-situ characterization of the charging mechanisms. ONERA is currently involved in the design and testing of a compact multisensor instrument for in situ analysis of lunar dust properties in the frame of an EU-funded project led by BIRA-IASB in Belgium. The goal is to develop by the end of 2024 a sensor package, which will include a dust charge detector, a Langmuir and an E-field probe, for charge and size measurements of single dust particles. Our study focuses on the charge detector which is a polarized Faraday cup connected to a transimpedance amplifier (1011 V/A gain, 200 Hz bandwidth) and a digitization stage. Measurements are done with a 6 mm thick layer of JSC-1A. The background noise is low enough to measure charges of dust particles on a regolith surface after VUV irradiation with a precision lower than 1 fC. The time evolution of the signal is compared to numerical models in order to estimate the velocity and mass of dust particles, which could give valuable information about the charge over mass ratio. Additional cross-comparisons with numerical simulations obtained with SPIS-DUST, a 3D numerical tool developed at ONERA, are in qualitatively good agreement with the experimental data: we show that both positively and negatively charged particles are measured after VUV irradiation, which was not observed in previous experimental studies. This study thus paves the way for future lunar exploration missions that will require accurate measurements of the electrostatic properties of the lunar ground and allow us to define better safety margins.

Speaker: Rémi Pacaud (ONERA)

26 Electrodynamic Dust Shield Efficiency Characterisation under Vacuum Ultra-violet Irradiation for Lunar Application

Dust mitigation is one of the technologies crucial for extra-terrestrial explorations. This research presents a series of experiments on the electrodynamic dust shield (EDS) and how UV radiation affects its efficiency on selected lunar simulants (LHS-1 and LMS-1 from Exolith Lab) across a range of particle sizes, quantities and surface materials. In this experimental study, a VUV (vacuum ultra-violet) is used with \SI{1500}{V} AC electric field to mobilise the dust particles resting on either glass, Kapton or Beta cloth, inside a vacuum chamber at $~10^{-6}\si{\milli\bar}$. The dust removal efficiency is characterised by three different quantifying methods, weighing, optical microscope inspection and solar array light transmission. The experiment results show that EDS activation under the presence of continuous UV exposure on the simulant particles improves the dust removal rate by 40 to 80 percentage points, across all surfaces, with the exception of certain particle size ranges on Beta cloth. Effects of forces in EDS' ability to mobilise particles, such as repulsive electrostatic force in tandem with some ionising mechanism such as photoemission, as well as dielectrophoretic forces, are discussed.

Speaker: Ya-Chun Wang (DLR)

27 Discussion

SPIS in industrial context: advances, shortcomings and recommendations

Friday, December 8

8:45 AM Coffee

SPIS and SPINE developments

New developments, latest news, and other topics

28 SPIS Modelling of the dielectrics charging during multipactor effect in HF components

The payload of satellites, especially telecommunications, uses High-Frequency (HF) com-ponents and high power. In vacuum, these components can be subject to the multipactor effect which is likely to create a degradation of the component performances and partial or complete deterioration. More generally, the multipactor risk is also present in all the HF devices that operate under vacuum conditions, as for example, in particle accelerators and nuclear fusion reactors.
Today the multipactor effect is well described for metallic waveguide and simple geometries. Its study remains difficult with HF components using dielectric materials that are usually used to reduce the RF payload weight. The dynamic of the multipactor phenomenon is affected by the presence of the dielectric able to charge under an electron flux. The charging dynamic occurs in the same time scale as the electron synchro-nization with the RF field and the multiplica-ion by secondary emission on the surfaces. In this situation, this initial multipactor effect can results in a self-extinction of the phenomena or degenerate into a corona discharge or into an electrostatic discharge enhanced by the HF field. The aim of this work is to predict the conditions resulting into these different phenomena.
We present simulations results of the multipactor effect in the presence of dielectric using a new SPIS module.
The effect of the initial electrostatic charge of dielectrics on the multipactor dynamic is pre-sented. We will point different cases that could potentially lead to corona or electrostatic discharge following the multipactor. In other situations, a space charge saturation is observed. Even in the case of a multipactor extinction, we observe a residual surface potential that remains. It is probable that this residual charge can produce an electrostatic discharge.

Speaker: Dr Nicolas Fil (CNES)

29 Towards a High-Performance version of SPIS

The current version of the SPIS presents some performances limits, especially for the electrical propulsion (EP) and lunar dust applications. The dusty environments simulations usually require fully kinetic descriptions of the particles dynamics in large simulations domains, leading to long simulations. On the other hand, in the EP case, there is a strong coupling between the thusters, cathodes, spacecraft elements and the environment, strongly constraining the Poisson equation and electric circuit solvers. These two solvers are not parallelized even the particle pusher was already parallelized. A solution to significantly improve the performances of SPIS is to parallelize and optimize these solvers and to rebuild the numerical core of SPIS to target HPC systems such as clusters of computers. We present the work that was initiated in the context of an ESA contract to implement a HPC version of SPIS and the expected performances for EP and dust applications.

Speaker: Ludivine Leclercq (ONERA)

30 New SPIS developments in SPIS Maintenance activity

The developments implemented in SPIS for the first milestone of the SPIS Maintenance activity will be presented in the ESA contract 4000140340/23/NL/CRS/nh.

Speaker: Benjamin RUARD (Artenum)

31 Latest News on the new SPINE website

Speaker: Arnaud Trouche (Artenum)

32 General information and 30th Spine Conclusion

SDAB (invitation only)