Control system-plasma synchronization and naturally occurring edge localized modes in a tokamak
Abstract
Edge Localised Modes (ELMs) naturally occur in tokamak plasmas in high confinement mode. We find in ASDEX Upgrade that the plasma can transition into a state in which the control system field coil currents, required to continually stabilize the plasma, continually oscillate with the plasma edge position and total MHD energy. These synchronous oscillations are one-to-one correlated with the occurrence of natural ELMs; the ELMs all occur when the control system coil current is around a specific phase. This suggests a phase synchronous state in which nonlinear feedback between plasma and control system is intrinsic to natural ELMing, and in which the occurrence time of a natural ELM is conditional on the phase of the control system field coil current.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jun 01, 2018
- Source ID
- 10.1063/1.5025333
Entities
People
- Louis Giannone
- N. W. Watkins
- Peter Lang
- R. O. Dendy
- Sandra Chapman
- The Asdex Upgrade Team
Organizations
- Air Force Office of Scientific Research
- Boston University
- Culham Centre for Fusion Energy
- Engineering and Physical Sciences Research Council
- Horizon 2020
- London School of Economics and Political Science
- Max Planck Institute of Plasma Physics
- The Open University
- UK Fulbright Commission
- University of Warwick