Heat flux and scrape-off layer width scaling in NSTX and NSTX-U

While it has been shown experimentally that the inter-ELM scrape-off layer width, $\lambda_q$ in tokamaks scales as I$_p^{-1}$, the underlying physical mechanism for this scaling is not yet understood. Additionally, the physics behind the broadening of the heat flux profile during detachment, described by the S parameter in the so-called Eich fitting function [Eich NF 2013], is just beginning to be explored. During the final run campaigns of NSTX, it was shown experimentally that the addition of evaporative lithium wall coatings reduced $\lambda_q$ and S and correlated with a reduction in overall divertor pressure. Conversely during detachment experiments with CD$_4$ injection, while divertor total pressure increased during CD$_4$ injection, both $\lambda_q$ and S increased correspondingly. This is in qualitative agreement with measurements made on other tokamaks and shows a clear scaling of $\lambda_q$ and S with upstream density, which is used as a proxy for divertor density. Expected behavior and preliminary results from NSTX-U will also be presented.