DIII-D Frontiers Experiments Reveal the Interaction of Energetic Electrons and Magnetic Islands Confirming Major Findings of the MMS Mission

We report the first direct comparison of data from DIII-D frontiers experiments and NASA's Magnetospheric Multiscale (MMS) mission, revealing how magnetic islands interact with energetic electrons (EEs) in plasmas from lab to space. Magnetic islands efficiently trap both bulk plasma electrons and energetic sub-populations, increasing local electron densities near island O-points. We also observe that island bifurcation, which creates additional X-points, is a viable mechanism for electron acceleration. In DIII-D, Profile Reflectometer and CO2 Interferometer data confirm enhanced bulk densities near O-points, while synchrotron emission shows >10 MeV electrons confined in islands at the q=1 and q=2 surfaces. Hard X-rays reveal periodic de-confinement of these EEs as the q=2 island bifurcates from a 2/1- to 4/2-mode structure. TRIP3D simulations with collisions show a transition from classical diffusion to superdiffusion near X-points, pointing to magnetic topology changes as a driver for electron acceleration. MMS observations show similar behavior in Earth's magnetotail. Fast Plasma Investigation data reveal that bulk electrons accumulate at O-points, while bursts of EEs originate near X-points. These findings inform how evolving island structures contribute to runaway electron generation and expulsion during tokamak disruptions. Reproducing magnetotail-like dynamics in DIII-D provides a controlled platform for studying cross-field transport in both fusion and space plasmas.