Kinetic Equilibrium Reconstruction and Stability Analysis of KSTAR Plasmas Supporting Disruption Event Characterization and Forecasting

High fidelity kinetic equilibrium reconstructions are an essential requirement for accurate stability and disruption prediction analyses to support continuous operation of high beta KSTAR tokamak plasmas. The present work significantly expands prior magnetics-only equilibrium reconstruction capability. [1] The present kinetic equilibrium reconstructions include Thomson scattering data, charge exchange spectroscopy data, and allowance for fast particle pressure in addition to external magnetics and shaping field current data, and inclusion of vacuum vessel and passive plate currents following an approach used successfully in NSTX. [2] In addition, up to 25 channels of Motional Stark Effect data are used to constrain the local magnetic field pitch angle to produce reliable evaluation of the safety factor, q, profile. Approaches to minimize variation of the reconstructed pressure and magnetic pitch angle profiles within the data error are examined to reduce uncertainty in the subsequent stability analysis used for disruption event characterization and forecasting (DECAF).

[1] Y.S. Park, S.A. Sabbagh, J.W. Berkery, et al., Nucl. Fusion 51 (2011) 053001.

[2] S.A. Sabbagh, A.C. Sontag, J.M. Bialek, et al., Nucl. Fusion 46 (2006) 635.