Local compressional and global Alfv\'{e}n eigenmode structure on NSTX and their effect on core energy transport

A novel method for localized absolute reflectometer measurements of density fluctuations $\delta n$ using a synthetic diagnostic has provided new insight into CAE {\&} GAE amplitude, structure, and associated energy transport in NSTX spherical torus. The new technique is more accurate than previous analysis producing substantially different amplitudes. CAE {\&} GAE activity has been shown to correlate with core anomalous electron thermal transport in high-power beam heated NSTX plasmas [Stutman PRL09] making these measurements of significant interest. High frequency modes (17--33{\%} $f_{ci})$ are identified as GAEs {\&} CAEs in a 6 MW beam heated plasma. The synthetic diagnostic allows direct testing of HYM, a leading CAE {\&} GAE stability code that predicts substantial transport via CAE-KAW coupling [Belova PRL15]. Measured GAE structures show edge peaks, and are broad {\&} flat in the core with $\delta n$/$n$\textasciitilde 10$^{\mathrm{-5}}$--10$^{\mathrm{-4}}$. In contrast, CAEs have broad core peaks with $\delta n$/$n$\textasciitilde 10$^{\mathrm{-4}}$--10$^{\mathrm{-3}}$. The GAE measurements are used with theory for mode induced stochastization of electron drift orbits [Gorelenkov NF10] to predict the core electron thermal diffusivity ($\chi_{e})$, which shows the low amplitudes cannot explain the high $\chi_{e}$. The theory has been modified to include the CAEs, preliminarily showing negligible increase. Linear HYM simulations show GAE structures similar to those above.