Slowly rotating 3d field for locked mode avoidance and h-mode recovery in diii-d

A slowly rotating 3D field has been considered a promising approach for preventing the locking and growth of NTMdriven disruptions in high beta plasmas, or enhancing the H-mode recovery. Recently, M3D [1], numerical simulations have found new properties of the q=1 modes in these plasmas that suggest the possibility of using the rotating 3D field to sustain the plasma core against quasi-interchange (QI)-driven sawtooth crashes, at the same time as avoiding NTMs locking at q>1. The characteristic q~1 QI modes are found to have dominant n=1 and 2 toroidal harmonics of comparable magnitude that are well suited to interact with the external 3D field. Preliminary experimental observations in hybrid configuration discharges support the possibility of quasi-interchange mode control with the slowly rotating 3D field and suggest that it can be explored simultaneously with the control of NTM locking avoidance.