  Stellarators, together with tokamaks, represent the two mainstream approaches
to realizing fusion energy via toroidal magnetic confinement of highly ionized
gases - plasmas - at extremely high temperatures. Improving our understanding
of how macroscopic flows impact equilibrium and dynamics in stellarators closes
a significant knowledge gap and is necessary to advance the physics basis of
stellarators as a fusion pilot plant (FPP) concept. This is especially critical
for the US stellarator design program, in both the public and private sectors,
where stellarator FPP concepts are based almost exclusively on leveraging
quasisymmetries. With this submission we invite the community to consider how
the need for improving physics understanding of flows in advanced stellarators
can serve as a catalyst for diagnostic and measurement innovation. This
includes the identification of synergies with on-going technology development
activities as well as opportunities to leverage new and emerging capabilities
that may stem from hardware improvements and software, for example, application
of AI/ML and workflow integration and management.
