Progress in Tokamak Disruption Simulation (TDS) SciDAC Project

The Tokamak Disruption Simulation (TDS) SciDAC project aims to develop

the physics basis for effective disruption mitigation.  It has focused on the distinct physics of

thermal (TQ) and current quench (CQ), and the integration of different physics

components for whole device modeling. Here we highlight several recent

progresses. The first is the kinetic physics underlying TQ

when large-scale MHD modes open up nested flux surfaces, and how the

magnetic connection length correlates with the time scale for core

temperature collapse, which can explain the vast range of

TQ time observed in experiments. The

second is the atomic processes underlying high-Z impurity purge by

hydrogen injection during CQ, which is

essential for a number of recent proposals for ITER runaway

mitigation. Here the roles of runaways in collisional ionization and

excitation, and the charge exchange between

different species, are explored with collisional-radiation

modeling. The third is integrated modeling of CQ, which involves the initial Ohmic-to-runaway

current conversion and latter process of either runaway termination or

runaway-to-Ohmic current back-conversion.  The final thrust is the

computational effort within TDS that explores a range of advanced

numerical and computational methods for integrated

disruption simulation.