Comparison of simulated heat transport in NSTX via high frequency Alfv\'{e}n eigenmode-induced electron orbit modification with~TRANSP power balance modeling.

Compressional (CAE) and global (GAE) AEs have been hypothesized to cause an anomalously high electron thermal diffusivity ($\chi_{\mathrm{e}})$ routinely inferred via TRANSP power balance modeling in the core ($r/a$ \textless $\sim $ 0.3) of NSTX beam heated plasmas. New simulations with the guiding-center code ORBIT test a leading proposed transport mechanism: electron orbit stochastization by multiple modes. Simulations with a set of modes identified as GAEs in a high performance, beam heated plasma---using experimentally determined amplitudes, frequencies and wave numbers---yield a $\chi_{\mathrm{e}}$ insufficient to match TRANSP. To produce a comparable $\chi_{\mathrm{e}}$, the amplitudes must be increased by a factor of $\sim $ 10, which is outside the bounds of measurement uncertainty. Many observed modes, identified as CAEs, could not be included without modifications to ORBIT. These are in progress. However, given the uncertainties in identification, it is informative to calculate $\chi _{\mathrm{e}}$ assuming all the observed modes are GAEs. This leads to substantially higher $\chi_{\mathrm{e}}$, although an amplitude increase by a factor \textgreater $\sim $ 3 is still necessary to match TRANSP.