  The goal of FASER, ForwArd Search ExpeRiment at the LHC, is to discover
light, weakly-interacting particles with a small and inexpensive detector
placed in the far-forward region of ATLAS or CMS. A promising location in an
unused service tunnel 480 m downstream of the ATLAS interaction point (IP) has
been identified. Previous studies have found that FASER has significant
discovery potential for new particles produced at the IP, including dark
photons, dark Higgs bosons, and heavy neutral leptons. In this study, we
explore a qualitatively different, `beam dump' capability of FASER, in which
the new particles are produced not at the IP, but through collisions in
detector elements further downstream. In particular, we consider the discovery
prospects for axion-like particles (ALPs) that couple to the standard model
through the $a \gamma \gamma$ interaction. TeV-scale photons produced at the IP
collide with the TAN neutral particle absorber 130 m downstream, producing ALPs
through the Primakoff process, and the ALPs then decay to two photons in FASER.
We show that FASER can discover ALPs with masses $m_a \sim 30 - 400~\text{MeV}$
and couplings $g_{a\gamma\gamma} \sim 10^{-6} - 10^{-3}~\text{GeV}^{-1}$, and
we discuss the ALP signal characteristics and detector requirements.
