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P: Fachverband Plasmaphysik

P 5: Poster I

P 5.19: Poster

Dienstag, 31. August 2021, 14:00–16:00, P

Development of a model based early heating advanced scenario for ASDEX-Upgrade — •Raphael Schramm, Alexander Bock, Maximilian Reisner, Jörg Stober, Hartmut Zohm, and The ASDEX Upgrade Team — Max-Planck Institut für Plasmaphysik, Garching, Germany

Advanced Tokamak scenarios offer improved stability, confinement and pulse length compared to standard scenarios due to an increase of the plasma’s bootstrap current (j_bs ∝ q ∇ p). They are accessed by manipulating the safety factor profile q through external actuators, which can be applied during the current ramp-up (early heating), or after an equilibrium is reached (late heating). The former allows for a longer discharge and more varied current distributions, but due to the volatility of the early plasma, creating such a scenario experimentally, with feed-forward control usually takes a lot of trial and error.

To combat this, a model, capable of predicting the plasma response to actuator changes with reasonable accuracy and a run-time of only a few minutes, has been developed in the transport code ASTRA. It includes Gyro-Bohm based core transport, edge transport according to a recently developed scaling law as well as the L/H-transition based on the heating power at the separatrix. Multiple fitting factors have been scaled according to a set of reference discharges and a good agreement between simulation and experiment has been achieved.

Using this model, an advanced scenario with early heating and an elevated q-profile has been developed and successfully tested at ASDEX-Upgrade.