c) Photon energy (eV) Lyman- d) Y(ℏ,…) variables ℏ photon energy mono monochromator band incidence angle light polarization/linear s polarization incidence ------------ electron affinity work function photo-electric threshold dielectric constant PP Photon energy (eV) TEY (electrons/photons) A sample vacuum resistance chamber wall emission current measurement mesh ℏ Material Emission onset (eV) Coverglass Mg alloy Aerodag Graphit 33 Ti ITO MLI 6.21 5.5 5.86 5.69 5.96 6.09 Solar spectral irradiance a) b) X 0.0153 ITO MLI LNG P3 LNG P2 LNG P4 LNG P1 Mg alloy ITO radiator Solar panels Solar spectral irradiance (W/m2 nm) L. Manenti1,2, S. Kaloš1,2, I. Sarnoff1,2, P. Oikonomou1,2, H. Roberts1,2, L. Pasquali3,4,5, N. Mahne4, A. Giglia4, S. Nannarone4, E. Magnano4, S. Nappini4, S. Els6, F. Arneodo1,2 1 Division of Science, New York University, Abu Dhabi, United Arab Emirates 2 Center for Astrophysics and Space Science (CASS), New York University Abu Dhabi Abu Dhabi, United Arab Emirates 3 Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena, Italy 4 CNR- Officina dei Materiali (IOM), Basovizza, Trieste, Italy 5 Department of Physics, University of Johannesburg, Johannesburg, South Africa 6 Mohammed Bin Rashid Space Centre, Dubai, United Arab Emirates e-mail: magnano@iom.cnr.it Acknowledgments This work is part of the Emirates Lunar Mission (ELM), conducted by the Mohammed Bin Rashid Space Center (MBRSC) in Dubai, UAE, and is funded by the ICT Fund under the Mars 2117 initiative. P.O., F.A., S.K. acknowledge funding support from the European Union’s Horizon 2020 Program under the AHEAD2020 project (grant agreement n. 871158). L.M, S.K., I.S., P.O., H.R., F.A. acknowledge the support of Tamkeen under the NYU Abu Dhabi Research Institute grant CASS. S.N. has the pleasure to acknowledge the scientific exchanges with G.Tchoudinlv which gave shape to part of this work. Original paper L. Manenti et al., Space Science Reviews 220, 83 (2024), DOI:10.1007/s11214-024-01116-8. Fig. 1 Figure 1. (a) Rashid rover with mast deployed (top) and stowed (bottom). Instruments include 4 Langmuir probes (LNG P1–4) for sheath profiling, a microimager, thermal imager, wheel sensors, and front/rear cameras. (b) Solar spectral irradiance (W/m2·nm) from 5 to 1000 eV to be used with Y(ℏω,…) in sheath modeling; Lyman-alpha indicated. Left panel x-axis scaled as shown. (c) Sketch of electron distribution from valence band to vacuum level (EK = 0), highlighting valence and secondary emission. (d) Measured Y(ℏω,…) (Y depends on the inset variables) for coverglass, Mg alloy, Aerodag, Graphite, Ti, ITO. Dashed linear extrapolation at the onset are shown for eye guide. The experimental error was ~4×10-3 e-/photon. The impinging photon flux was measured by an absolute photo-diode. Inset illustrates the principle of the measurements: the emitted current (number of electrons per s) circulates in the closed mesh versus photon energy (monochromatized synchrotron beam). Emission onsets are shown in the inset table. Photon sources and instrumentation Elettra Highlights 2024–2025 139
RkJQdWJsaXNoZXIy MjQ4NzI=