  Degradation of first wall materials due to plasma disturbances severely limit
both the lifetime and longevity of fusion reactors. Among the various kinds of
disturbances, type I edge localized modes (ELMs) in particular present
significant design challenges due to their expected heat loading and relative
frequency in next step fusion reactors. Plasma gun devices have been used
extensively to replicate ELM conditions in the laboratory, however feature
higher density, lower temperatures, and thus higher flow collisionality than
those expected in fusion conditions. This work presents experimental
visualizations that indicate strong shocks form in gun devices over spatial and
temporal scales that precede ablation dynamics. These measurements are used to
validate detailed magnetohydrodynamic simulations that capture the production
of plasma jets and the shielding effect collisionality plays in particle
transport to material surfaces. Simulations show that self-shielding effects in
plasma guns reduce the free streaming heat flux by up to 90% and further reduce
the incoming particle kinetic energy impinging on material surfaces. These
simulations are performed over a range of operating conditions for gun devices
and a discussion is provided regarding how existing experimental measurements
can be interpreted when extrapolating to fusion conditions.
