Modeling of Ablatant Deposition from Electromagnetically Driven Radiative Pellets for Disruption Mitigation Studies

Abstract

The electromagnetic particle injector (EPI) concept is advanced through the simulation of ablatant deposition into ITER H-mode discharges with calculations showing penetration past the H-mode pedestal for a range of injection velocities and granule sizes concurrent with the requirements of disruption mitigation. As discharge stored energy increases in future fusion devices such as ITER, control and handling of disruption events become critical issues. An unmitigated disruption could lead to failure of the plasma-facing components resulting in financially and politically costly repairs. Methods to facilitate the quench of an unstable high-current discharge are required. With the onset warning time for some ITER disruption events estimated to be less than 10 ms, a disruption mitigation system needs to be considered that operates at injection speeds greater than gaseous sound speeds. Such an actuator could then serve as a means to augment presently planned pneumatic injection systems. The EPI uses a railgun concept whereby a radiative payload is delivered into the discharge by means of the J×B forces generated by an external current pulse, allowing for injection velocities in excess of 1 km/s. The present status of the EPI project is outlined, including the addition of boost magnetic coils. These coils augment the self-generated railgun magnetic field and thus provide a more efficient acceleration of the payload. The coils and the holder designed to constrain them have been modeled with the ANSYS code to ensure structural integrity through the range of operational coil currents.