Investigation of MHD Stability and Active Mode Control Supporting Disruption Avoidance on KSTAR*

H-mode plasma operation in KSTAR has surpassed the computed n = 1 ideal no-wall stability limit for several seconds in duration. High normalized beta operation was limited by resistive tearing instabilities rather than RWMs. Kinetic equilibrium reconstructions including MSE data have been developed for accurate stability and transport analysis. The reconstructed high performance equilibria can exhibit significant variation of the q-profile dependent upon the broadness of the bootstrap current profile as computed by TRANSP code. The stability of the observed m/n = 2/1 tearing mode is computed by using the resistive DCON code and the M3D-C¹ code. MISK code analysis examining global MHD stability modified by kinetic effects shows significant passive kinetic stabilization of RWMs. To accurately measure the dynamics of unstable RWMs expected to onset at higher beta by utilizing the newly installed second NBI system, real-time mode identification and active control has been developed in the KSTAR PCS including magnetic sensor compensation of the prompt applied field and the field from the induced current in the passive conductors. This analysis provides the foundation for disruption prediction and avoidance research on KSTAR.