Experimental electronic stopping cross-section of tungsten bulk and sputter-deposited thin films for slow protons, deuterons and helium ions

Sputter-deposition of ultra-thin film stacks from EUROFER97 and tungsten: characterisation and interaction with low-energy D and He ions

“…The backscattered particles are detected by a set of two microchannel plates in a chevron stack configuration at a fixed central angle of 129°covering a solid angle of 2 × 10 -4 sr The recorded charge-integrated spectra are subsequently converted to the energy domain. The system provides a high depth resolution in the monolayer regime [32] and has been earlier employed for obtaining electronic stopping powers from the energy width of spectra in backscattering geometry [21,33] as well as the intensity of charge normalized backscattering spectra [33,34].…”

“…Figure 5 presents the energy-converted ToF-LEIS spectra for 10 keV He + on the EUROFER97/W/Si sample and on the bulk W-Ref in black and red line + symbol, respectively. The black solid line represents the most compatible TRBS simulation using an optimum corrected ε for the sputter-deposited film of EUROFER97 as well as using the recently measured stopping cross-section of W (ε W ) at Uppsala University (Shams-Latifi 2023) [8] for the W layer. The two black dashed lines represent TRBS simulations using ±10% ε of EUROFER97 exhibiting the sensitivity of the position of the W signal to the SCS of EUROFER97.…”

“…The two black dashed lines represent TRBS simulations using ±10% ε for EUROFER97 demonstrating the sensitivity of the position of the W signal to the SCS of EUROFER97. The pink solid line represents the TRBS simulation in bulk W-Ref using Shams-Latifi 2023 ε W [8] for deuterons. In both figures 5 and 6, the arrows labelled as KE 0,W and KE 0,Fe mark the expected energy of a primary ion with the respective initial energy elastically scattered from a W and an Fe atom in a scattering angle of 129°, respectively.…”

“…Studying the interfacing of this material and PFC-candidate materials is thus a topic of continual interest [4,5]. In this context, low-energy ions have been extensively used to study near-surface properties of EUROFER97 which are relevant for such component interfacing as well as potential unexpected plasma exposure [6][7][8].…”

“…Quantitative knowledge of the electronic SCS of lowactivation steels for plasma species is thus not only an essential input parameter for simulating potential plasma exposure and radiation damage as well as in hindsight of potential steel-based devices, but also a prerequisite for quantitative depth profiles in post-mortem analysis using low-energy ion beams in e.g. (time-of-flight) lowenergy ion scattering (ToF-)LEIS, secondary ion mass spectrometry (SIMS) or related techniques [8,10,11]. At present, however, no experimental reference electronic stopping power at energies below the Bragg peak [12] for any steel including EUROFER97 exists [13].…”