Investigation of the influence of the ion heat flux on access to regimes of improved energy confinement in Alcator C-Mod.

Edge Physics Forum

  • Date: Mar 29, 2017
  • Time: 03:30 PM - 04:30 PM (Local Time Germany)
  • Speaker: Matthias Schmidtmayr
  • Location: Garching
  • Room: Seminarraum D3
The role of the edge ion heat flux for transitions from L-mode to H-mode in Alcator C-Mod is investigated. Several selected discharges from the low to medium density range in C-Mod were analyzed by time dependent power balance analysis using the transport code TRANSP. The ion heat flux was calculated by adding the power from the ion cyclotron resonance heating deposited in the ion channel and the electron-ion heat exchange. These calculations showed that the surface integrated edge ion heat flux obtained just prior to the L-H transition increases linearly with line average density, which agrees with previous results from AUG. It appears, as if a critical amount of heat flux per particle is necessary for the transition. The comparison of the results of this work and previous research at AUG lead to a simple linear scaling law for the critical edge ion heat flux necessary for the transition into H-mode.
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