Planetary space weather experiments at the I-ENA facility at INAF-IAPS in Rome

Introduction

The Ion and Energetic Neutral Atom (I-ENA) beam facility at INAF-IAPS provides a unique platform to investigate the interaction of modifiable ion and neutral beams with a wide range of samples and detectors [1, 2]. For over two decades, this facility has supported studies on the interaction of the solar wind with planetary environments, with particular emphasis on ENA detection and charge exchange processes. Recently, the scientific focus has been related to backscattered and sputtered particle yields, as well as exosphere refilling processes [3, 4]. These efforts have contributed to the characterisation, testing, and calibration of the SERENA particle packed of the cornerstone space mission, BepiColombo, to Mercury [5]. Today, the I-ENA facility supports active space missions (e.g., BepiColombo/SERENA/ELENA), early-phase instrument developments (e.g., SWEATERS [6]), and testing campaigns for materials, detectors, and subsystems, particularly in the context of low-energy (0.5–5 keV) interaction processes.

 

I-ENA facility

The I-ENA laboratory includes two high vacuum chambers (10^-7 mbar), each with a respective ion source. The first chamber is equipped with a He⁺/Ar ion source (Penning-type cold cathode) with an energy range of 0.5-5 keV, and is capable of producing fluences of 10¹⁴ ions/cm² over a 12 hr irradiation period. This source can be modulated in intensity using various pinholes and an Einzel lens system. ENAs may be generated using a charge exchange cell. Within the chamber, there is a translation-rotation stage, to move samples horizontally, vertically, and rotate them through 360°. This chamber is currently equipped with a Quadrupole Mass Spectrometer (QMS), with a mass range up to 200 u and a sensitivity down to partial pressures of 10^-14 mbar. The QMS is used for residual gas measurements and to investigate volatile species within the chamber.  An image and schematic of this chamber is shown in Figure 1.

Figure 1. One of the I-ENA high vacuum chambers, and schematic of the set up.

The second, newest chamber hosts a higher intensity He⁺/Ar source, capable of producing beams with fluences of 10¹⁸ ions/cm² over a 12 hr irradiation period. Consequently, this beam is more suited to experiments requiring higher fluences to replicate geological timescales on planetary bodies. The chamber is also within a clean (ISO 7) environment, suitable for testing instrumentation for space applications.   

 

Experiments

The I-ENA laboratory facilitates calibrations of particle detectors and controlled experiments using ion/neutral beams to irradiate diverse surface analogues for investigating planetary space weather. A core activity of the lab has been the development and testing of space instrumentation. Notably, ELENA (Emitted Low-Energy and Neutral Atoms), part of the SERENA suite onboard BepiColombo, was developed, tested, and calibrated at I-ENA and the University of Bern. ELENA detects backscattered ENAs as well as magnetospheric and solar wind ions in the 10 eV–5 keV energy range. The ELENA Flight Spare (FS) is still housed in the lab and will be used in upcoming experiments to investigate ion-surface interactions with Mercury analogues. These studies aim to provide ground truth for interpreting data collected by BepiColombo.

The I-ENA lab team is currently expanding its capabilities to establish an irradiation facility for analogue testing. These experiments are designed to investigate irradiation-driven processes, building on our expertise in planetary space weather. By collaborating with external facilities that specialise in sample analysis, we aim to study the coupled exosphere–magnetosphere–surface system as a whole. Current experiments include collaborations within INAF, for example irradiating the enstatite achondrite meteorite, NWA 13278, using a He beam of 4.5 keV to simulate the solar wind irradiating Mercury’s surface. Full details of this experiment can be found in the abstract in this session (Galiano, A., et al. (2025). Space weathering simulation on the Aubrite meteorite NWA 13278, putative analogue of Mercury. EPSC-DPS Joint Meeting 2025). Current work involves investigating release processes on different materials using the QMS, and using the ELENA FS to investigate backscattering processes of the solar wind, in collaboration with other BepiColombo teams [7].

 

Acknowledgements: This Activity is supported by ASI contract SERENA/BepiColombo Fase E.

 

References

[1] De Angelis, E., et al. (2009). A facility to study the particles released by ion-sputtering process. European Planetary Science Congress (EPSC), Potsdam.

[2] De Angelis, E., et al. (2024). Accelerated ion-ENA beam for planetary space weather. Congresso Nazionale di Scienze Planetarie (CNSP), Bormio.

[3] Milillo, A., et al. (2005). Surface-Exosphere-Magnetosphere System of Mercury. Space Science Reviews, 117, 397–443. https://doi.org/10.1007/s11214-005-3593-z

[4] Mura, A., et al. (2006). Neutral Atom Emission from Mercury. Advances in Geosciences, 3. https://doi.org/10.1142/5913-vol3

[5] Orsini, S., et al. (2021). SERENA: Particle Instrument Suite for Determining the Sun–Mercury Interaction from BepiColombo. Space Science Reviews, 217, 19. https://doi.org/10.1007/s11214-021-00801-9

[6] De Angelis, E., et al. (2022). An innovative ENA instrument for space weather monitoring: SWEATERS (Space WEATher ENA Radiation Sensors) project. 44th COSPAR Scientific Assembly.

[7] Barraud, O., et al. (2025). Mercury-Y Lab: A scientific rehearsal for future BepiColombo observations. Lunar and Planetary Science Conference (LPSC).