HBT-EP program: MHD dynamics and active control through 3D fields and currents

The HBT-EP active mode control research program aims to: (i) understand the physics of scrape-off layer currents (SOLC) and interactions between the helical plasma edge and conducting boundary structures, (ii) test new methods for measurement and mode control that integrate optical and magnetic detector arrays with both magnetic and SOLC feedback, and (iii) understand fundamental MHD issues associated with disruptions, resonant magnetic perturbations, and SOLC. A two-color multi-energy EUV/SXR tangential array has been used to study internal MHD mode structure and tearing mode dynamics. A biased electrode was used to induce a strong layer of sheared ExB flow to achieve H-mode plasmas with edge turbulence dominated by the ion temperature gradient mode extending previous findings of EAST and TCABR. Disruption dynamics and current paths in the SOL and the vacuum vessel have been studied, and a model developed for the MHD mode rotation frequency after the current quench phase. Stable non-disruptive operating space boundaries in HBT-EP have been mapped using a variational autoencoder neural network with a reduced dimensional representation. GPU active control system improvement is being pursued using tomographic reconstruction and improved basis function representation of the poloidal EUV emissivity for adaptive mode suppression.