  Electronic stopping cross section of tungsten for light ions was
experimentally measured in a wide energy interval (20 to 6000 keV for protons
and 50 to 9000 keV for helium) in backscattering and transmission geometries.
The measurements were carried out in three laboratories (Austria, Germany and
Sweden) using five different set-ups, the stopping data deduced from different
data sets showed excellent agreement amongst each other, with total uncertainty
varying within 1.5 - 3.8\% for protons and 2.2 - 5.5\% for helium, averaged
over the respective energy range of each data set. The final data is compared
to available data and to widely adopted semi-empirical and theoretical
approaches, and found to be in good agreement with most adopted models at
energies around and above the stopping maximum. Most importantly, our results
extend the energy regime towards lower energies, and are thus of high
technological relevance, e.g., in fusion research. At these low energies, our
findings also revealed that tungsten - featured with fully and partially
occupied f- and d-subshells, respectively, can be modeled as an electron gas
for the energy loss process.
