MARFE stability and movement in an ELMy H-mode NSTX discharge

The results of a comparison of Multifaceted Asymmetric Radiation From the Edge (MARFE) theory with experiment in the National Spherical Torus Experiment (NSTX) are presented. A variety of MARFE behavior was observed using a fast-framing camera. A basic MARFE theory was applied to NSTX Multi-Pulse Thomson scattering (MPTS) and charge-exchange recombination spectroscopy (CHERS) data. MARFE theory showed some limited agreement with experiment, but uncertainty in the separatrix location constrained the analysis. A method based on shifting iso-Te flux surfaces was used to estimate the separatrix location. The movements of MARFEs in NSTX are interpreted to result from diamagnetic heat flux driven drifts relative to the background plasma velocity and imply slowing edge poloidal rotation and/or changing edge profiles before a large ELM.