Speaker
Dr
Nicholas Eidietis
(General Atomics)
Description
A finite-state off-normal and fault response (ONFR) system is presented that provides the required supervisory logic for robust disruption avoidance and machine protection in tokamaks. Robust event handling is critical for ITER and future large tokamaks, where plasma parameters will necessarily approach stability limits and many systems will operate near their engineering limits. The ONFR system presented provides four critical features of a robust event handling system: sequential responses to cascading events, event recovery, simultaneous handling of multiple events and actuator prioritization. This system has been deployed during live experiments on DIII-D and KSTAR. In the most complex demonstration on DIII-D, the ONFR algorithm asynchronously applies “catch and subdue" electron cyclotron current drive (ECCD) injection scheme to suppress a virulent 2/1 neoclassical tearing mode, subsequently shuts down ECCD for machine protection when the plasma becomes over-dense, and enables rotating 3D field entrainment of the ensuing locked mode with synchronized ECCD deposition on the locked mode O-point to allow a safe ramp-down, all in the same discharge without user intervention.
*Supported in part by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, using the DIII-D National Fusion Facility, under Award DE-FC02-04ER54698. Work on KSTAR was supported by the Korean Ministry of Science and ICT under the KSTAR project and DOE Award DE-SC0010685.
| Country or International Organization | United States of America |
|---|---|
| Paper Number | EX/P6-22 |
Primary author
Dr
Nicholas Eidietis
(General Atomics)
Co-authors
Brian Sammuli
(General Atomics)
Dr
David Humphreys
(General Atomics)
Michael Walker
(General Atomics)
Dr
Sang-hee Hahn
(National Fusion Research Institute)
Wilkie Choi
(Columbia University)
