Non-linear MHD simulations of type I ELM cycles

ASDEX Upgrade Seminar

  • Datum: 10.02.2020
  • Uhrzeit: 12:20 - 13:30
  • Vortragende(r): Andres Cathey
  • Ort: Garching
  • Raum: Seminarraum L6, 2.Stock Süd
  • Gastgeber: IPP
Andres Cathey: Non-linear MHD simulations of type I ELM cycles
A mechanism responsible for the explosive onset of edge localized modes (ELMs) in fusion plasmas has been identified by performing, for the first time, non-linear magnetohydrodynamic simulations of realistic large ELM cycles. Before the ELM crash, the interplay between the destabilising pressure gradient and the stabilising plasma flows is found to be in favour of the plasma flows at all times during the inter-ELM period. However, an instability driven by the large edge current density affects the plasma such that the imbalance is turned in favour of the destabilising terms. This allows for further instabilities to grow explosively and for a violent ELM crash to occur. Once sufficient energy is lost, the interplay returns to be in favour of the plasma flows, thus marking the end of the ELM crash after only a few hundreds of microseconds. The simulated time scales and losses are directly comparable to experimental observations. These simulations are a major step forward towards predictive simulations of natural ELMs and mitigation techniques in ITER.
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