  Accurately predicting the electronic energy deposition of ions in materials
is an important challenge in both fundamental and applied research. While
employing ab initio simulations to investigate electronic stopping of ions in
matter holds promise, its combined use with experimental measurements paves the
way for obtaining reliable data. In this paper, we present a collaborative
study using real-time time-dependent density functional theory and experimental
methods to determine the electronic stopping power of hydrogen and helium ions
in tungsten, a primary candidate material for future nuclear fusion devices.
While calculated stopping powers in hyperchanneling trajectories are
significantly lower than the experimental data, off-center and random
geometries demonstrate a better agreement. We show that the deviation from
velocity proportionality for both projectiles traversing the hyperchanneling
directions can be explained through the existence of a threshold velocity
leading to the activation of semicore states. Additionally, we analyse the
pseudopotential and the trajectory dependence of computed electronic energy
losses. It is demonstrated that the role of including inner-shell electrons
varies depending on the velocity range. While these states play a crucial role
at high projectile velocities by introducing additional dissipation channels,
their impact diminishes in the low-velocity range. Finally, we introduce a
simple expression that links electronic energy losses in different trajectories
to local electron density, and we show that utilizing this formula allows for
quite accurate predictions of stopping powers around the Bragg peak.
